HK1214496B - Powered roll-in cots having wheel alignment mechanisms - Google Patents

Description

Power simple bed with wheel alignment mechanism for loading vehicle

Cross reference to related patent applications

This application claims benefit and priority from U.S. provisional patent application No.61/769,918 filed on 27.2.2013 and U.S. provisional patent application No.61/835,042 filed on 14.6.2013, the entire disclosures of both of which are incorporated herein by reference.

Technical Field

The present invention relates generally to emergency cot, and more particularly, to a powered lift cot having a wheel alignment mechanism.

Background

There are a variety of emergency cot devices in use today. Such emergency cot may be designed to deliver and load a patient into an ambulance.

For example, Ferno-Washington, Inc. of Wilmington, OhioThe cot is a manually actuated cot that can provide stability and support for a load of about 700 pounds (about 317.5 kg).The cot includes a patient support portion attached to a wheeled chassis. The wheeled undercarriage includes an X-shaped frame geometry that can be switched between nine alternative positions. One recognized advantage of this simple bed design is that the X-shaped frame provides minimal flex and a low center of gravity at all selectable positions. Another recognized advantage of this cot design is that the selectable positions may provide better leverage for manually lifting and loading obese patients.

Another example of a cot designed for obese patients is the POWERFLEX + Powered cot of Ferno-Washington, Inc. The powerflex + Powered cot includes a battery-Powered actuator that can provide sufficient power to lift a load of about 700 pounds (about 317.5 kg). One recognized advantage of this cot design is that the cot can lift an obese patient from a lower position to a higher position, i.e., can reduce the need for the operator to lift the patient.

Another variation is a multi-function boarding emergency cot having a patient support stretcher removably attached to a wheeled chassis or transporter. The patient support cradle, when removed for use separately from the transporter, can be shuttled horizontally over the included wheelsets. One recognized advantage of this cot design is that the stretcher can be individually accessed in an emergency vehicle, such as a recreational vehicle, truck, modular ambulance, aircraft, or helicopter, where space and reduced weight are important.

Another recognized advantage of this cot design is that the individual stretchers can be more easily transported over uneven terrain and outside of locations where the patient cannot be transported with the complete cot. Examples of such conventionally known cot beds can be found in, for example, U.S. patent nos. 4,037,871, 4,921,295 and international publication No. WO 01701611.

While the above-described multi-function boarding emergency cot has been adequate for its intended purpose in its entirety, it has not been satisfactory in all respects. Therefore, there is a need for a powered lift cot having a wheel alignment mechanism.

Disclosure of Invention

Embodiments described herein relate to a universal multi-purpose boarding emergency cot that may provide improved management of cot weight, improved balance, and/or easier loading at any cot height, while being able to roll into various types of rescue vehicles, such as ambulances, trucks, station wagons, aircraft, and helicopters.

According to one embodiment, the get-on cot comprises: a support frame; a first pair of legs pivotably and slidably coupled to the support frame; and a first pair of hinge members. Each hinge member is pivotably coupled to the support frame and pivotably coupled to one of the first pair of legs. Get on bus simple and easy bed still includes: a first wheel link pivotably coupled to the first pair of legs; and a wheel alignment mechanism incorporated into at least one of the first pair of legs. The wheel alignment mechanism includes a timing mechanism coupled to the first wheel connection and one of the first pair of hinge members. The first pair of legs and the first pair of hinge members pivot relative to each other at a relative angular rotation ratio, and the wheel alignment mechanism rotates the wheel alignment mechanism relative to the first pair of hinge members at a reduction ratio. The relative angular rotation ratio of the first pair of legs and the first pair of hinge members is approximately inversely proportional to the reduction ratio of the wheel alignment mechanism.

In another embodiment, the roll-in cot comprises: a support frame; a first pair of legs pivotably coupled to the support frame; and a first pair of hinge members, wherein each hinge member is pivotably coupled to the support frame and pivotably coupled to one of the first pair of legs. Get on bus simple and easy bed includes: a first wheel link pivotably coupled to the first pair of legs; and a wheel alignment mechanism incorporated into at least one of the first pair of legs. The wheel alignment mechanism includes a timing mechanism, a first hub coupled with one of the first pair of hinge members, and a second hub coupled with a first wheel connection. One of the first pair of hinge members or the first pair of legs is slidably coupled to a support frame. The first pair of legs and the first pair of hinge members pivot relative to each other in a relative angular rotation ratio. The timing mechanism is coupled to the first hub and the second hub and transmits relative rotation of the first pair of hinge members to the first wheel connection. The wheel alignment mechanism rotates the wheel alignment mechanism relative to the first pair of hinge members at a reduction ratio. The relative angular rotation ratio of the first pair of legs and the first pair of hinge members is approximately inversely proportional to the reduction ratio of the wheel alignment mechanism.

In another embodiment, the roll-in cot comprises: a support frame having a front end and a rear end; a pair of front legs pivotably coupled to the support frame; a front hinge member pivotably coupled to the support frame and pivotably coupled to one of the pair of front legs; and a front wheel link pivotably coupled to the pair of front legs. Get on bus simple and easy bed still includes: a pair of rear legs pivotably coupled to the support frame; a rear hinge member pivotably coupled to the support frame and pivotably coupled to one of the pair of rear legs; and a rear wheel link pivotably coupled to the pair of rear legs. The roll-in cot further comprises a wheel alignment mechanism incorporated into at least one of the pair of front legs or the pair of rear legs, the wheel alignment mechanism comprising a timing mechanism coupled to the respective hinge member and the respective wheel linkage. The pair of front legs and the pair of rear legs are pivotable relative to the support frame and are pivotable independently of each other. The pair of front legs and the pair of front hinge members pivot relative to each other at a relative angular rotation ratio, and the pair of rear legs and the pair of rear hinge members pivot relative to each other at a relative angular rotation ratio. The timing mechanism is coupled to the first hub and the second hub and transmits relative rotation of the respective pair of hinge members to the respective wheel connections. The wheel alignment mechanism causes the wheel alignment mechanism to rotate the hinge members relative to the respective pair of hinge members at a reduction ratio, and the relative angular rotation ratio of the respective pair of legs and the respective hinge members is approximately inversely proportional to the reduction ratio of the wheel alignment mechanism.

These and additional features provided by embodiments of the present invention will be more fully understood from the following detailed description, with reference to the accompanying drawings.

Drawings

The following detailed description of specific embodiments of the present invention can be best understood when read in conjunction with the following drawings, where like structure is indicated with like reference numerals and in which:

FIG. 1 is a perspective view of a cot according to one or more embodiments shown or described herein;

FIG. 2 is a top view of a cot according to one or more embodiments shown or described herein;

FIG. 3 is a perspective view of a cot according to one or more embodiments shown or described herein;

FIG. 4 is a perspective view of a cot according to one or more embodiments shown or described herein;

FIGS. 5A-5C are side views of a sequence of raising and/or lowering a cot according to one or more embodiments shown or described herein;

6A-6E are side views of a loading and/or unloading sequence of a cot according to one or more embodiments shown or described herein;

FIG. 7A is a perspective view of an actuator according to one or more embodiments shown or described herein;

FIG. 7B schematically illustrates an actuator according to one or more embodiments shown or described herein;

FIG. 8 is a perspective view of a cot according to one or more embodiments shown or described herein;

FIG. 9 schematically illustrates a timing mechanism according to one or more embodiments shown or described herein;

FIG. 10 schematically illustrates a cross-sectional view of the front leg of the cot taken along line A-A of FIG. 9 according to one or more embodiments shown or described herein;

figure 11 schematically illustrates a detailed side view of a wheel alignment mechanism including a shock absorber according to one or more embodiments shown or described herein;

FIG. 12a schematically illustrates a detailed side view of a timing mechanism for one of the front or rear legs of the roll-in cot according to one or more embodiments shown or described herein;

FIG. 12b schematically illustrates a detailed side view of a timing mechanism for one of the front or rear legs of the roll-in cot according to one or more embodiments shown or described herein;

FIG. 13 schematically illustrates a side perspective view of a portion of a timing mechanism for one of the front or rear legs of the roll-in cot, according to one or more embodiments shown or described herein;

FIG. 14 schematically illustrates a side perspective view of a hub of a timing mechanism for boarding one of the front or rear legs of the cot, according to one or more embodiments shown or described herein; and

FIG. 15 schematically illustrates a side perspective view of a hub of a timing mechanism according to one or more embodiments shown or described herein, with certain components removed for clarity.

The embodiments illustrated in the drawings are illustrative and exemplary and are not intended to be limiting of the embodiments described herein. Furthermore, the various features of the drawings and the embodiments will be more fully apparent and understood in view of the detailed description.

Detailed Description

Referring to fig. 1, an on-board cot 10 for transport and loading is shown. The roll-in cot 10 includes a support frame 12 including a front end 17 and a rear end 19. As used herein, the front end 17 is synonymous with the loading end, i.e., the end of the upper cot 10 that is first loaded onto a loading surface. Rather, as used herein, the rear end 19 is the end of the upper cot 10 that is loaded last onto the loading surface. Additionally, it is noted that when the cot 10 is loaded with a patient, the patient's head may be oriented proximate the front end 17 and the patient's feet may be oriented proximate the rear end 19. Thus, the phrase "head end" may be used interchangeably with the phrase "front end" and the phrase "foot end" may be used interchangeably with the phrase "rear end". Further, it is noted that the phrases "front end portion" and "rear end portion" are interchangeable. Thus, although the phrases are used consistently throughout for clarity, the embodiments described herein may be reversed without departing from the scope of the invention. In general, as used herein, the term "patient" refers to anything that is or has previously survived, such as a human, an animal, a cadaver, or the like.

Referring collectively to fig. 2 and 3, the front end portion 17 and/or the rear end portion 19 may be telescoping. In one embodiment, the front end 17 may be extended and/or retracted (as generally indicated by arrow 217 in FIG. 2). In another embodiment, the rear end 19 may be extended and/or retracted (as generally indicated by arrow 219 in FIG. 2). Accordingly, the overall length between the front end portion 17 and the rear end portion 19 may be increased and/or decreased to accommodate patients of various sizes. Further, as shown in fig. 3, front end 17 may include a telescoping lift handle 150. Telescoping lift handle 150 may telescope away from support frame 12 to provide lift leverage and telescoping toward support frame 12 to be stored. In some embodiments, telescoping lift handle 150 is pivotally coupled to support frame 12 and is rotatable from a vertical handle orientation to a side handle orientation and vice versa. Telescoping lift handle 150 may be locked in a vertical handle orientation and a side handle orientation. In one embodiment, when telescoping lift handle 150 is in the side handle orientation, telescoping lift handle 150 provides a gripping surface adjacent support frame 12 and each is configured to be gripped by a hand with the palm generally facing up and/or down. Conversely, when telescoping lift handles 150 are in the vertical handle orientation, telescoping lift handles 150 may both be configured to be grasped by a hand with the thumb pointing generally upward and/or downward.

Referring collectively to fig. 1 and 2, the support frame 12 may include a pair of parallel lateral side members 15 extending between a front end 17 and a rear end 19. Various structures for the lateral side members 15 are conceivable. In one embodiment, the lateral side members 15 may be a pair of spaced apart metal rails. In another embodiment, the lateral side member 15 includes an undercut portion 115 that is engageable with an accessory clamp (not shown). Such accessory clamps may be used to removably couple a patient care accessory (e.g., a support rod for an intravenous drip) to the undercut portion 115. The undercut portions 115 may be provided along the entire length of the lateral side members to allow the attachment to be removably clamped to a number of different locations on the roll-in cot 10.

Referring again to fig. 1, the roll-in cot 10 further includes a pair of retractable and extendable front legs 20 coupled with the support frame 12 and a pair of retractable and extendable rear legs 40 coupled with the support frame 12. The roll-in cot 10 may comprise any rigid material, such as a metal structure or a composite structure. Specifically, the support frame 12, the front leg portion 20, the rear leg portion 40, or a combination thereof may include carbon fiber and a resin structure. As described in greater detail herein, the roll-in cot 10 may be raised to multiple heights by extending the front legs 20 and/or the rear legs 40, or the roll-in cot 10 may be lowered to multiple heights by retracting the front legs 20 and/or the rear legs 40. It is noted that terms such as "raise", "lower", "upper", "lower" and "height" are used herein to refer to the distance relationship between objects measured along a line parallel to gravity using a reference (e.g., a surface supporting a cot).

In particular embodiments, the front leg 20 and the rear leg 40 may each be coupled to the lateral side member 15. Referring to fig. 8, the front leg 20 may include a front carriage member 28 that is slidably coupled to the rails of the lateral side members 15, and the rear leg 40 may also include a rear carriage member 48 that is slidably coupled to the rails of the lateral side members 15. Referring to fig. 5A-6E and 10, as the roll-in cot 10 is raised or lowered, the carriage members 28 and/or 48 slide inward or outward along the tracks of the lateral side members 15, respectively.

As shown in fig. 5A-6E, the front and rear legs 20, 40 may cross each other when the cot is viewed from the side, particularly where the front and rear legs 20, 40 are coupled to the support frame 12 at respective locations (e.g., the lateral side members 15, as shown in fig. 1-4). As shown in the embodiment of fig. 1, the rear legs 40 may be disposed inboard of the front legs 20, i.e., the front legs 20 are spaced apart from each other a greater distance than the rear legs 40 are spaced apart from each other such that the rear legs 40 are each positioned between the front legs 20. In addition, the front and rear legs 20, 40 may include front and rear wheels 26, 46 that enable the roll-on cot 10.

In one embodiment, the front wheels 26 and the rear wheels 46 may be swivel casters or swivel lock wheels. As discussed below, the front wheels 26 and the rear wheels 46 may be synchronized when the roll-in cot 10 is raised and/or lowered to ensure that the plane of the roll-in cot 10 is substantially parallel to the plane of the wheels 26, 46. For example, each rear wheel 46 may be coupled to a rear wheel connector 47, and each front wheel 26 may be coupled to a front wheel connector 27. The front wheel attachments 27 and rear wheel attachments 47 may rotate to control the plane of the wheels 26, 46 as the roll-in cot 10 is raised and/or lowered.

A locking mechanism (not shown) may be provided in one of the front wheel attachments 27 and the rear wheel attachments 47 to allow an operator to enable and/or disable wheel direction locking. In one embodiment, the locking mechanism is coupled to one of the front wheels 26 and/or one of the rear wheels 46. The locking mechanism transitions the wheels 26, 46 between a rotational state and a direction-locked state. For example, in the rotated state, the wheels 26, 46 may be freely rotated, which enables the roll-in cot 10 to be easily turned. In the direction locked state, the wheels 26, 46 may be actuated to a straight orientation by an actuator (e.g., solenoid actuator, remotely operated servo mechanism, and the like), i.e., the front wheels 26 are oriented and locked in a straight direction, and the rear wheels 46 are free to rotate so that an operator pushing from the rear end 19 directs the roll-in cot 10 forward.

Referring again to fig. 1, the roll-in cot 10 may further include a cot actuation system including a front actuator 160 configured to move the front legs 20 and a rear actuator 180 configured to move the rear legs 40. The cot actuation system may include a unit (e.g., a central motor and pump) configured to control the front actuator 160 and the rear actuator 180. For example, the cot actuation system may include a housing having a motor that can drive the front actuator 160, the rear actuator 180, or both, using valves, control logic, etc. Alternatively, as shown in fig. 1, the cot actuation system may comprise separate units configured to individually control the front actuator 160 and the rear actuator 180. In this embodiment, the front actuator 160 and the rear actuator 180 may each include a separate housing, with a separate motor driving either actuator 160 or 180. Although the actuators are shown as hydraulic actuators or chain lift actuators in embodiments of the invention, it is contemplated that various other configurations are suitable.

Referring to fig. 1, a front actuator 160 is coupled to the support frame 12 and is configured to actuate the front legs 20 and raise and/or lower the front end 17 of the roll-in cot 10. Additionally, a rear actuator 180 is coupled to the support frame 12 and is configured to actuate the rear legs 40 and raise and/or lower the rear end 19 of the roll-in cot 10. The cot actuation system may be motorized, hydraulic, or a combination thereof. Further, it is contemplated that the roll-in cot 10 may be powered by any suitable power source. For example, the roll-in cot 10 may include a battery capable of providing a nominal voltage, such as about 24V or about 32V, as its power source.

Front actuator 160 and rear actuator 180 are operable to actuate front leg 20 and rear leg 40 simultaneously or independently. As shown in fig. 5A-6E, simultaneous and/or independent actuation allows the roll-in cot 10 to be set to various heights.

Any actuator suitable for raising and lowering the support frame 12 and retracting the front and rear legs 20, 40 is contemplated herein. As shown in fig. 3 and 8, the front actuator 160 and/or the rear actuator 180 may include a chain lift actuator (e.g., the chain lift actuator of Serapid, ltd, sterling, michigan). Alternatively, the front actuator 160 and/or the rear actuator 180 may also include wheel and axle actuators, hydraulic jack actuators, hydraulic column actuators, telescoping hydraulic actuator electric motors, pneumatic actuators, hydraulic actuators, linear actuators, screw actuators, and the like. For example, the actuators described herein can provide a dynamic force of about 350 pounds (about 158.8kg) and a static force of about 500 pounds (about 226.8 kg). Further, the front actuator 160 and the rear actuator 180 may be operated by a central motor system or a plurality of independent motor systems.

In one embodiment, as schematically illustrated in fig. 1-2 and 7A-7B, the front actuator 160 and the rear actuator 180 comprise hydraulic actuators for actuating the roll-in cot 10. In the embodiment shown in fig. 7A, the front actuator 160 and the rear actuator 180 are dual piggy-back hydraulic actuators. A dual pack hydraulic actuator includes four hydraulic cylinders having four extension rods that pack (i.e., mechanically couple) in pairs with each other. Thus, a dual piggyback actuator includes a first hydraulic cylinder having a first rod, a second hydraulic cylinder having a second rod, a third hydraulic cylinder having a third rod, and a fourth hydraulic cylinder having a fourth rod. Such a hydraulic actuator is described in more detail in commonly assigned U.S. patent No.7,996,939.

While the cot actuation system is typically powered, the cot actuation system may further include a manual release component (e.g., a button, a tensioning member, a switch, a connector, or a lever) configured to allow an operator to manually raise or lower the front and rear actuators 160, 180. In one embodiment, the manual release member disconnects the drive units of the front and rear actuators 160, 180 to facilitate manual operation. Thus, for example, when the drive unit is disconnected and the roll-in cot 10 is manually raised, the wheels 26, 46 may remain in contact with the ground. The manual release member may be provided at a plurality of locations on the upper truck cot 10, for example, on the rear end portion 19, or on the side of the upper truck cot 10.

To determine whether the roll-in cot 10 is level, a sensor (not shown) may be utilized to measure distance and/or angle. For example, the front actuator 16 and the rear actuator 18 may each include an encoder that determines the length of each actuator. In one embodiment, the encoder is a real-time encoder that is operable to detect movement of the entire length of the actuator or a change in the length of the actuator when the cot is powered or unpowered (i.e., manually controlled). While a variety of encoders are contemplated, in one commercial embodiment, the encoder may be an optical encoder manufactured by midwest sports products, ltd, of the township, minnesota, usa. In other embodiments, the cot includes an angle sensor that measures the actual angle or change in angle, such as a potentiometer rotation sensor, a hall effect rotation sensor, or the like. The angle sensor is operable to detect the angle of any pivotally coupled portion of the front leg 20 and/or the rear leg 40. In one embodiment, an angle sensor is operably coupled to the front and rear legs 20, 40 to detect a difference (angle) between the angle of the front leg 20 and the angle of the rear leg 40. The loading state angle may be set to, for example, an angle of about 20 ° or any other angle indicating that the boarding easy bed 10 as a whole is in the loading state (indicating loading and/or unloading). Therefore, when the angle exceeds the loading state angle, the getting-on-easy bed 10 can detect that it is in the loading state and perform some actions according to the loading state.

It should be noted that the term "sensor" as used herein refers to a device that measures a physical quantity and converts the physical quantity into a signal that is related to the measured value of the physical quantity. Furthermore, the term "signal" refers to an electrical, magnetic, or optical waveform capable of being transferred from one location to another, such as a current, voltage, flux, DC, AC, sine wave, triangular wave, square wave, or the like.

Referring now to fig. 3, the front legs 20 may also include a front cross beam 22 extending horizontally between and movable with the pair of front legs 20. The front leg 20 also includes a pair of front hinge members 24 pivotally coupled at one end to the support frame 12 and pivotally coupled at an opposite end to the front leg 20. Similarly, the pair of rear legs 40 includes a rear cross beam 42 that extends horizontally between and is movable with the pair of rear legs 40. The rear legs 40 also include a pair of rear hinge members 44 pivotally coupled at one end to the support frame and pivotally coupled at an opposite end to one of the rear legs 40. In particular embodiments, the front and rear hinge members 24, 44 may be pivotally coupled to the lateral side members 15 of the support frame 12. As used herein, "pivotally coupled" means that two objects are coupled together to resist linear motion and to facilitate rotation or oscillation between the two objects. For example, the front and rear hinge members 24, 44 do not slide relative to the front and rear carriage members 28, 48, respectively, but rotate or pivot when the front and rear legs 20, 40 are raised, lowered, retracted or released. As shown in the embodiment of fig. 3, the front actuator 16 may be coupled to the front cross beam 22 and the rear actuator 18 may be coupled to the rear cross beam 42.

Referring to fig. 4, the front end 17 may also include a pair of front loading wheels 70 configured to assist in loading the roll-in cot 10 onto a loading surface 500 (e.g., the floor of an ambulance). The roll-in cot 10 may include sensors operable to detect the position of the front loading wheels 70 relative to the loading surface 500 (e.g., distance above the surface or contact with the surface). In one or more embodiments, the front loading wheel sensors include contact sensors, proximity sensors, or other suitable sensors effective to detect when the front loading wheels 70 are above the loading surface 500. In one embodiment, the front load wheel sensor is an ultrasonic sensor aligned to directly or indirectly detect the distance from the front load wheel to the surface below the load wheel. In particular, the ultrasonic sensors described herein are operable to provide an indication when the surface is within a definable distance range from the ultrasonic sensor (e.g., when the surface is greater than a first distance but less than a second distance). Thus, the definable range may be set such that a positive indication is provided by the sensor when a portion of the roll-in cot 10 is proximate to the loading surface 500.

In another embodiment, the plurality of front loading wheel sensors may be in series such that the front loading wheel sensors are only activated when both front loading wheels 70 are within a definable range of the loading surface 500 (i.e., the distance may be set to indicate that the front loading wheels 70 are in contact with the surface). As used herein, "activation" refers to the front loading wheel sensor sending a signal to the control box 50 that the front loading wheels 70 are all above the loading surface 500. It may be important to ensure that both front loading wheels 70 are on the loading surface 500, especially in situations where the cot 10 is loaded into an ambulance at an incline.

In the embodiments described herein, the control box 50 includes or is operably coupled to a processor and a memory. The processor may be an integrated circuit, a microchip, a computer, or any other computing device capable of executing machine-readable instructions. The electronic memory may be RAM, ROM, flash memory, a hard drive, or any device capable of storing machine-readable instructions. Additionally, it is noted that a distance sensor may be coupled to any portion of the roll-in cot 10 to enable the determination of the distance between the lower surface and the components, such as the front end 17, the rear end 19, the front load wheels 70, the front wheels 26, the intermediate load wheels 30, the rear wheels 46, the front actuator 16, or the rear actuator 18.

In other embodiments, the roll-in cot 10 has the capability to communicate with other devices, such as ambulances, diagnostic systems, cot accessories, or other medical equipment. For example, the control box 50 may include or may be operatively coupled to a communication member operable to send and receive communication signals. The communication signal may be a Controller Area Network (CAN) protocol, a bluetooth protocol, a wireless personal area network protocol, or any other communication protocol.

The front end 17 may also include a hook engagement lever 80 that is generally disposed between the front load wheels 70 and is operable to rotate forward and rearward. While the hook engaging bar 80 of fig. 3 is U-shaped, various other configurations may be used, such as a hook, straight bar, curved bar, etc. As shown in fig. 4, the hook engagement lever 80 is operable to engage a loading surface hook 550 on the loading surface 500. The loading surface hooks 550 are common on the floor of an ambulance. The engagement of the hook engagement rod 80 and the loading surface hook 550 may prevent the roll-in cot 10 from sliding backwards from the loading surface 500. Further, the hook engagement rod 80 may include a sensor (not shown) that detects engagement of the hook engagement rod 80 and the loading surface hook 550. The sensor may be a contact sensor, a proximity sensor, or any other suitable sensor operable to detect engagement of the loading surface hooks 550. In one embodiment, the engagement of the hook engagement rod 80 and the loading surface hook 550 may be configured to activate the front actuator 16 and thereby allow the front leg 20 to retract for loading onto the loading surface 500.

Still referring to fig. 4, the front legs 20 may include intermediate loading wheels 30 attached to the front legs 20. In one embodiment, the intermediate load wheels 30 may be disposed on the front legs 20 adjacent the front cross member 22. Similar to the front loading wheels 70, the intermediate loading wheels 30 may include sensors (not shown) operable to measure the distance of the intermediate loading wheels 30 from the loading surface 500. The sensor may be a contact sensor, a proximity sensor or any other suitable sensor operable to detect when the intermediate loading wheel 30 is above the loading surface 500. As explained in more detail herein, the load wheel sensors may detect that the wheels are on the floor of the transport, thereby allowing the rear legs 40 to be safely retracted. In certain additional embodiments, the intermediate loading wheel sensors may be in series, similar to the front loading wheel sensors, such that the two intermediate loading wheels 30 must be above the loading surface 500 before the sensors indicate that the loading wheels are above the loading surface 500, i.e. before sending a signal to the control box 50. In one embodiment, the intermediate load wheel sensor may provide a signal that causes the control box 50 to activate the rear actuator 18 when the intermediate load wheel 30 is within a set distance of the loading surface. Although the figures show the intermediate loading wheels 30 only on the front legs 20, it is further contemplated that the intermediate loading wheels 30 may be disposed on the rear legs 40, or may be disposed at any other location on the lift bed 10 such that the intermediate loading wheels 30 cooperate with the front loading wheels 70 to facilitate loading and/or unloading (e.g., support the frame 12).

Referring now to fig. 9, in one embodiment, the roll-in cot 10 includes a wheel alignment mechanism 300. The wheel alignment mechanism 300 provides automatic vertical positioning of the front wheel attachments 27 as the front legs 20 are raised and lowered. By positioning the front wheel attachments 27 in the proper orientation, predictable rolling of the roll-in cot 10 can be achieved with the front legs 20 positioned in any of a variety of positions from fully raised to fully lowered, as well as intermediate positions therebetween. Although the particular discussion and description herein of the positioning of the wheel alignment mechanism relative to the front leg 20 of the roll-in cot 10 is provided, it should be understood that the roll-in cot 10 according to the present invention may incorporate the wheel alignment mechanism 300 into any extendable leg assembly, including, for example, the rear leg 40. Thus, in describing the legs, hinge members, wheel connections and wheel alignment mechanisms of the roll-in cot 10, "first" and "second" may be used interchangeably herein with "front" and "rear" without reference to the positioning of particular components.

As described above, during the raising and lowering operations of the front leg portions 20, the front leg portions 20 and the front hinge members 24 are coupled to each other and pivot relative to each other. The front leg 20 is coupled to the support frame 12 by a carriage 28 (fig. 8) that allows the front leg 20 to slide in a longitudinal direction relative to the support frame 12 and rotate relative to the support frame 12. The front hinge member 24 is coupled to the support frame 12 and the front leg 20 and is pivotable relative to the support frame 12 and the front leg. Because the freedom of movement of the front leg portion 20 and the hinge member 24 is limited, the front leg portion 20 and the hinge member 24 move relative to the support frame 12 and relative to each other according to a predetermined kinematic relationship when the front leg portion 20 is subjected to a raising or lowering operation. Such relative angular rotation between the front leg 20 and the hinge member 24 may be predictable and repeatable. In some embodiments, the relative angular rotation between the front legs 20 and the hinge members 24 may be substantially constant (e.g., within about 10%) over the entire stroke of the front legs 20 as the front legs move from the fully retracted position to the fully extended position. In other embodiments, the relative angular rotation between the front legs 20 and the hinge members 24 may vary throughout the stroke of the front legs 20.

Because the angle of inclination of the front legs 20 relative to the ground varies between the fully retracted position and the fully extended position, the angular orientation of the front wheel attachments 27 relative to the ground also varies. Wheel alignment mechanism 300 according to the present invention maintains the angular inclination of front wheel attachments 27 relative to the ground throughout the travel of front legs 20 as the front legs move from the fully retracted position to the fully extended position.

As described above, the relative positioning and coupling of the support frame 12, the front legs 20, and the front hinge members 24 defines a kinematic relationship between the front legs 20 and the front hinge members 24 that causes the front legs 20 and the front hinge members 24 to move in a relative angular rotation with respect to each other as the front legs move between the fully retracted position and the fully extended position. Such relative angular rotation between the front leg 20 and the front hinge member 24 may be calculated based on the positioning of the front leg 20 and the front hinge member 24 relative to the support frame 12. Overall, the front hinge member 24 moves to a greater extent relative to the front leg 20 than the front leg 20 moves relative to the support frame 12. In the embodiment shown in fig. 9, the front hinge 20 moves rotationally to the front leg 20 at an average relative angle that is approximately twice the movement of the front leg 20 relative to the support frame 12 when evaluated over the entire travel of the front leg from the fully retracted position to the fully extended position. However, it should be understood that the roll-in cot 10 according to the present invention may have various relative angular rotation values. To maintain the relative angular inclination of the front wheel attachments 27 with respect to the ground, the wheel alignment mechanism 300 may include elements for relative angular rotation of the front legs 20 and the front hinge members 24.

In the embodiment shown in fig. 9, the wheel alignment mechanism 300 includes a timing member 130 disposed in at least a portion of the front leg 20. In the embodiment shown in fig. 9, the timing member 130 is a timing belt 131 that frictionally engages a hub setting member positioned in the front leg 20. As discussed in more detail below, the timing member 130 may have various configurations. Timing belt 131 is coupled with hubs 132 that are pivotally coupled to the various components of front leg 20. The first hub 132a is coupled to the front hinge member 24 such that the first hub 132a remains fixed in position relative to the front hinge member 24 and rotates relative to the front leg 20 as the front leg 20 is raised and lowered. Thus, the first hub 132a changes the position of the timing belt 131 relative to the front leg 20 as the front leg 20 moves between the fully raised position and the fully lowered position.

Second hub 132b is coupled to front wheel attachment 27. The second hub 132b remains fixed in position relative to the front wheel attachment 27 and rotates relative to the front leg 20 as the front leg 20 is raised and lowered. The timing belt 131 rotates the position of the front wheel attachment 27 as the front leg 20 is raised and lowered. Thus, as front leg 20 moves between the fully retracted position and the fully lowered position, first hub 132a and second hub 132b change the position of the timing belt to reposition the orientation of front wheel attachment 27.

The timing belt 131 and the first and second hubs 132a, 132b can have various mating interface configurations. In one embodiment, the timing belt 131, the first hub 132a, and the second hub 132b are formed with grooves at their interface surfaces. However, alternative embodiments of the interface between the timing belt 131 and the first and second hubs 132a, 132b are contemplated, such as a flat interface or a V-shaped interface. The timing belt 131 may be composed of various materials including polymers and elastomers. The timing belt 131 may also be reinforced with various materials conventionally known for increasing the strength and/or durability of belts, including nylon, polyester, aramid, and the like.

Referring to FIG. 10, one embodiment of a hub portion 230 of the front leg 20 is shown. Hub portion 230 provides an interface between the components of hub 132 and front leg 20. As shown in fig. 10, hub portion 230 connects first hub 132a to front hinge member 24 via front leg 20. However, it should be understood that a similar hub portion may connect second hub 132b to front wheel connector 27 (see FIG. 9). Referring again to fig. 10, hub portion 230 includes a first hub 132a that is a partially encapsulated outer race 234. In some embodiments, the outer race 234 may be integrated into the front leg 20. Hub portion 230 may include a plurality of cover plates 232 positioned outside outer race 234, thereby allowing first hub 132a to rotate within outer race 234. The front hinge member 24 is coupled to the first hub 132a, for example, by a fastener 238 that passes through the front hinge member 24, the cover plate 232, and the first hub 132 a. Hub portion 230 maintains first hub 132a aligned with respect to front hinge member 24 such that when front hinge member 24 pivots with respect to front leg 20, first hub 132a pivots with respect to upper leg 20 at the same rate as front hinge member 24.

Referring again to fig. 9, during a raising or lowering operation of the front leg 20, the front hinge member 24 pivots relative to the front leg 20 such that the first hub 132a pivots relative to the front leg 20. When the first hub 132a engaged with the front hinge member 24 rotates, the timing belt 131 is dragged in one of two directions by the first hub 132a, and the rotation of the first hub 132a with respect to the front leg 24 is transmitted to the second hub 132b, which is similarly engaged with the timing belt 131. Second hub 132b is coupled to front wheel attachment 27 such that rotation of second hub 132b changes the orientation of front wheel attachment 27 relative to front leg 20.

In the embodiment shown in fig. 9, the diameter of the first hub 132a is smaller than the diameter of the second hub 132b such that the rotation of the first hub 132a is reduced compared to the second hub 132 b. Thus, the wheel alignment mechanism has a reduction ratio equal to the ratio of the diameter of the first hub 132a to the diameter of the second hub 132 b. In the embodiment shown in fig. 9, the ratio of the diameter of the first hub 132a to the diameter of the second hub 132b is approximately inversely proportional to the relative angular movement between the front leg 20 and the front hinge member 24. Because the angular inclination of front wheel attachment 27 is controlled by front leg 24 and front hinge member 24, and by first hub 132a and second hub 132b of wheel alignment mechanism 300, maintaining the ratio of the diameter of first hub 132a to the diameter of second hub 132b and the inverse relationship between the relative angular movement between front leg 20 and front hinge member 24 may maintain the orientation of front wheel attachment 27 with respect to level ground as front leg 20 moves between the fully retracted position and the fully extended position.

In the embodiment shown in fig. 9, the first hub 132a is about half the diameter of the second hub 132b coupled to the front wheel attachment 27. This corresponds to a solution having about 2: 1, and a front hinge member 24. Rotation Δ 1 of front hinge member 24 relative to front leg 20 causes rotation Δ 2 of front wheel attachment 27 relative to front leg 20, where rotation Δ 2 is half the magnitude of rotation Δ 1. Restated, when the front hinge member 24 is rotated 10 ° relative to the front leg 20, the front wheel connection 27 will be rotated 5 ° relative to the front leg 20 due to the relative sizes of the diameter of the first hub 132a and the diameter of the second hub 132 b.

Although the wheel alignment mechanism 300 described above incorporates a wheel having a diameter ratio of 1: 2, but it should be understood that the diameter ratio of the various first and second hubs 132a, 132b can be selected to provide a desired rotational ratio between the front hinge member 24 and the front wheel attachment member 27. In some embodiments, the diameter ratio of the first and second hubs 132a, 132b may be inversely proportional to the relative angular rotation provided by the front legs 20 and the front hinge members 24. In some embodiments, the diameter ratio of the first and second hubs 132a, 132b multiplied by the relative angular rotation of the front leg 20 and the front hinge member 24 may be within about 30%, including for example within about 25%, such as within about 20%, such as within about 15%, such as within about 10%, such as within about 5%. A lower diameter ratio multiplied by the relative angular rotation may indicate that the relative angular inclination of front wheel attachment 27 with respect to horizontal ground is more uniform throughout the travel of front leg 20 from the fully retracted position to the fully extended position. Thus, the roll-in cot 10 having the wheel alignment mechanism 300 according to the present invention may have a front wheel connector 27 that positions the front wheels 26 at an angular inclination in a variety of orientations of the front legs 20.

Still referring to fig. 9, the wheel alignment mechanism 300 may include at least one shock absorber 310. Shock absorber 310 is positioned relative to timing belt 131 and reduces the impact load applied to timing belt 131 when front wheel 26 contacts an obstacle, for example.

Referring now to fig. 11, the shock absorber is shown in more detail. Shock absorber 310 includes a housing 312 having an opening 314 for receiving a tensioner 318 and a belt relief passage 316. Tensioner 318 includes belt channel 319 and is positioned within opening 314 of housing 312. Shock absorber 310 further includes a damping assembly 320 comprising a tension member 322, a load dispersing element 324 and a compliant liner 326. In the embodiment shown in fig. 11, the tension member 322 is a threaded fastener that secures the damping assembly 320 to the follower 318. Shock absorber 310 may also include a plurality of cover plates 317 positioned along the outside of housing 312 to enclose shock absorber 310.

As shown in fig. 11, tensioner 318 is positioned within opening 314 of housing 312 and tensioner 318 is secured to housing 312 by a tensioning member 322. Timing belt 131 is introduced along belt release 316 of housing 312 and along belt channel 319 of tensioner 318. The path length of the timing belt 131 through the shock absorber 310 is greater than the linear distance of the belt release 316 along the housing 312 such that the effective length of the timing belt 131 (i.e., the estimated distance the timing belt 131 travels around the first and second hubs 132a, 132b as shown in fig. 9) is reduced with the shock absorber 310 installed.

The damping assembly 320 of shock absorber 310 includes a compliant liner 326. The compliant liner 326 may be made of a variety of materials including natural or synthetic elastomers. In another embodiment, at least one mechanical spring (not shown) may be disposed within the shock absorber 310 and perform the same function as the compliant liner 326 described herein. Additionally, the tensioning members 322 can be adjusted to provide a predetermined deformation of the compliant liner 326 so that variations in the size or material characteristics of the compliant liner 326 can be accommodated without adversely affecting the performance of the shock absorber 310.

As described above, the front wheel attachment 27 of the roll-in cot 10 is configured to be repositionable to its vertical orientation to maintain alignment of the front wheels 26 at multiple locations on the front leg 20. In operation of the roll-in cot 10, when the front wheels 26 contact an obstacle, such as when the roll-in cot 10 is moving, the contact between the front wheels 26 and the obstacle may tend to move the vertical orientation of the front wheel attachments 27 relative to the front legs 20. The rotational orientation of front wheel attachment 27 is captured by the interaction between second hub 132b, timing belt 131, first hub 132a and front hinge member 24. However, the impact between the front wheel 26 and the obstacle may exert a force on the timing belt 131. In the case where the timing belt 131 is not equipped with the shock absorber 310 described above, the magnitude of this force may tend to overload the timing belt 131.

The compliant liner 326 deforms when a load is applied to the damping assembly 320 tending to drag the load distributing element 324 in a direction toward the housing 312. When a pulsed load is applied to the timing belt 131 in an orientation that tends to increase the path length of the timing belt 131, the timing belt 131 positioned in the shock absorber 310 tends to "straighten" such that the tensioner 318 pulls the load spreading element 324 in a direction toward the housing 312. As the load distributing element 324 translates toward the housing 312, the compliant liner 326 deforms, thereby absorbing at least a portion of the impulse load. By absorbing at least a portion of the impulse load applied to the front wheels 26 at the compliant liner 326, the impulse load introduced into the timing belt 131 may be mitigated, thereby reducing the likelihood of an overload condition of the timing belt 131.

The material, cross-sectional area, and thickness of the compliant liner 326 may be selected such that a predetermined impulse load, such as an impact load associated with one of the front wheels 26 contacting an obstacle (e.g., curb) when the truck cot 10 is moving at walking speed with a 550 pound patient supine on the truck cot 10, will tend to deform the compliant liner 326 without causing a tension overload of the timing belt 131. Specifically, the timing belt 131 may be designed to have about a 50% safety factor under such loading conditions so that the timing belt 131 will maintain structural integrity in the event of the introduction of the impact event described above. In addition, when the timing belt 131 of the roll-in cot 10 is fitted with the shock absorber 310, the components of the shock absorber 310 deform to dissipate the force in the timing belt 131 associated with the front wheel 26 impacting the obstacle.

Embodiments of the roll-in cot 10 may include a plurality of shock absorbers 310 positioned along opposite sides of the timing belt 131. In the embodiment shown in fig. 9, the upper shock absorber 310a absorbs the impact load associated with the upper simple ride bed 10 moving in the forward direction (i.e., the load tending to increase the length of the timing belt 131 positioned relative to the upper shock absorber 310 a), while the lower shock absorber 310b absorbs the impact load associated with the upper simple ride bed 10 moving in the rearward direction (i.e., the load tending to increase the length of the timing belt 131 positioned relative to the lower shock absorber 310 a).

Still referring to fig. 9, wheel alignment mechanism 300 may further include at least one idler roller 330. Idler roller 330 contacts timing belt 131 and allows timing belt 131 to change planar orientation such that timing belt 131 can continue to engage first hub 132a and second hub 132b in applications where first hub 132a and second hub 132b do not have line-of-sight gaps. In some embodiments, idler roller 330 may comprise a bearing-mounted roller secured to front leg 20 and configured to rotate upon input of minimal friction to wheel alignment mechanism 300.

In other embodiments, both front legs 20 include wheel alignment mechanisms 300 as described above. In such an embodiment, raising or lowering the front end 17 of the support frame 12 by the front legs 20 causes rotation of the front wheel attachments 27. Additionally, the rear legs 40 may include a wheel alignment mechanism 300 similar to that described for the front legs 20, wherein raising or lowering the rear end 19 of the support frame 12 by the rear legs 40 causes rotation of the rear wheel connections 47. Thus, in embodiments where each of the front and rear legs 20, 40 includes a wheel alignment mechanism 300, the vertical orientation of the front and rear wheels 26, 46 may be maintained to ensure that the roll-on cot 10 is able to roll across surfaces of various cot heights. Thus, the upper cot 10 may be rolled in the fore/aft direction and/or the side-to-side direction when the support frame 12 is substantially parallel to the ground, i.e., when the front leg 20 and the rear leg 40 are actuated to approximately the same length. In addition, by maintaining the vertical orientation of the front and rear wheel attachments 27, 47 relative to the ground, the roll-on cot 10 may be rolled in the fore/aft direction and/or the side-to-side direction when the support frame 12 is substantially parallel to the ground and the front and rear legs 20, 40 are actuated to different lengths.

Referring now to fig. 12a, other embodiments of the roll-in cot may include a wheel alignment mechanism 400 having a timing mechanism 130 that is a timing chain 410. The timing chain 410 is coupled to a first hub 414 positioned adjacent to the support frame (shown in FIG. 1) and a second hub 412 positioned adjacent to one of the front or rear wheels (shown in FIG. 1). The first hub 414 and the second hub 412 are positioned in one of the front or rear legs (as shown in fig. 1) of the roll-in cot. Similar to the embodiment of the roll-in cot incorporating the timing belt shown above with respect to fig. 9-11, the timing chain 410 maintains the rotational orientation of the front or rear wheels relative to the support frame of the roll-in cot, thereby maintaining a rotational synchronous orientation of the wheels relative to the ground across which the roll-in cot traverses for all orientations of the front or rear legs throughout their range of motion. In various embodiments of the roll-in cot, the first hub 414 can be positioned at multiple locations along the front or rear leg. Rotation of the first hub 414 may be responsible for positioning the first hub 414 to maintain the rotational synchronization orientation of the wheels of the roll-up cot. Maintaining the radial orientation of the front and rear wheels may facilitate ease of entry into the cot when the legs are positioned in various orientations. In one embodiment, steering of the lift cot may be adversely affected in the event that the front or rear wheels are not rotationally aligned. Thus, maintaining the alignment of the front and rear wheels may improve handling characteristics of the roll-in cot.

Still referring to fig. 12a, the alignment mechanism 400 includes a timing chain 410 coupled with both a first hub 414 and a second hub 412. The timing chain 410 includes a coupler 416 that connects the timing chain 410 to the coupler such that the timing chain 410 is continuous around its perimeter. The coupler 416 may adjust the length of the timing chain 410 such that the timing chain 410 can be adjusted to accommodate changes in the distance between the first hub 414 and the second hub 412.

The alignment mechanism 410 may also include chain tensioners 418, 420 that change the position of the timing chain 410 to increase the estimated path distance of the timing chain 410 around the first and second hubs 414, 412. By increasing the path distance of the timing chain 410 around the first and second hubs 414, 412, the effective length of the timing chain 410 may be decreased, thereby increasing the tension on the timing chain 410. In some embodiments, the chain tensioners 418, 420 may include a spring mechanism that automatically changes the path length of the timing chain 410 to account for the relative translational movement between the first and second hubs 414, 412. In embodiments where the chain tensioners 418, 410 comprise spring mechanisms, the chain tensioners 418, 420 may absorb shock loads applied to the timing chain 410 by temporarily allowing the timing chain 410 to translate the chain tensioners 418, 420 thereby temporarily reducing the path length of the timing chain 410.

Referring now to fig. 12b, other embodiments of the roll-in cot 10 can include an alignment mechanism 410 having an idler roller 480 (similar to the idler roller 330 described above) that changes the orientation of the timing chain 410, but does not actively change the tension introduced into the timing chain 410. The idler roller 480 may position the timing chain 410 to avoid contact with elements of the cot leg to prevent inadvertent contact between the timing chain 410 and the cot leg.

Referring now to FIG. 13, a detailed view of the timing chain 410 is shown. In the illustrated embodiment, the timing chain 410 includes a plurality of links 430 connected to one another to form the timing chain 410. In the embodiment shown in FIG. 13, the timing chain 410 is a block-and-loop chain, however, other types of chains may be suitable for use in the design of the present invention, including roller chains, without departing from the scope of the present invention. In the embodiment shown in fig. 13, the orientation of the timing chain 410 relative to the first and second hubs 414 and 412 (see fig. 12) is substantially fixed to maintain the rotationally synchronized orientation of the first and second hubs 414 and 412. Thus, the orientation of the timing chain 410 relative to the first and second hubs 414, 412 is substantially fixed such that the engagement of the timing chain 410 with the first and second hubs 414, 412 is not altered. However, other embodiments of the alignment mechanism 400 may incorporate first and second hubs 414, 412 and a timing chain 410, the engagement of which is modified in operation.

The timing chain 410 includes a first hub mating portion 432 that is coupled to the first hub 414 (shown in FIG. 12). The first hub mating section 432 includes a plurality of attachment plates 436, 438 that are connected to one another by pins to form the first hub mating section 432. The attachment plates 436, 438 correspond in overall thickness to the links 430 that make up the rest of the timing chain 410, so that the first hub mating portion 432 can be easily incorporated into the timing chain 410. Each attachment plate 436, 438 includes at least one through hole 440 through the attachment plate 436, 428. When the attachment plates 436, 438 are aligned and assembled into the first hub mating section 432, the through holes 440 are aligned to allow for the insertion of fasteners, such as bolts, screws, or pins. Thus, the first hub mating section 432 may be resiliently coupled to the first hub 414 by a secure connection.

Referring now to fig. 14 and 15, one embodiment of the second hub 412 is shown. Referring to fig. 14, the second hub 412 includes a first cover plate 452 and a second cover plate 454 positioned opposite each other along an end of the second hub 412. The second hub 412 also includes a plurality of attachment plates 456 and bypass plates 458 that are disposed proximate to each other to form a central portion of the second hub 412. The first cover plate 452 of the second hub 412 is removed from the view of fig. 15 to more clearly show the attachment plate 456 and the bypass plate 458 of the second hub 412.

Referring now to fig. 15, the attachment plates 456 of the second hub 412 each include a securing tab 457 extending from a gap portion 459. The fixing protrusions 457 each include at least one through-hole 460 through which a fastener, such as a bolt, a screw, or a pin, may be inserted. When the plurality of attachment plates 456 and the plurality of bypass plates 458 are assembled and arranged with one another, the link 430 of the timing chain 410 may be inserted into the clearance area in the second hub 412 created by the bypass plates 458 such that at least a portion of the link 430 may be coupled to the attachment plates 456. The coupling of the timing chain 410 and the attachment plate 456 of the second hub 412 to each other provides a resilient attachment between the timing chain 410 and the second hub 412, thereby allowing the timing chain 410 to maintain the rotationally synchronized orientation of the first and second hubs 414, 412.

Although specific reference is made herein to attachment schemes of the timing chain 410 to the first and second hubs 414 and 412, it should be appreciated that these attachment schemes may be modified or varied to suit particular end user applications without departing from the scope of the present invention.

Referring again to fig. 3, the roll-in cot 10 may include a front actuator sensor 62 and a rear actuator sensor 64 configured to detect whether the front and rear actuators 16, 18 are in tension or compression, respectively. As used herein, the term "tension" refers to the pulling force detected by a sensor. Such pulling forces are typically associated with loads removed from the legs coupled to the actuators, i.e., the legs and/or wheels are suspended from the support frame 12 without contacting surfaces below the support frame 12. Further, as used herein, the term "compression" refers to the thrust force detected by the sensor. Such thrust is typically associated with the load applied to the legs coupled to the actuators, i.e., the legs and/or wheels are in contact with the surface below the support frame 12 and transfer compressive strain on the coupled actuators. In one embodiment, the front actuator sensor 62 and the rear actuator sensor 64 are coupled to the support frame 12; however, other locations or configurations are contemplated herein. The sensors may be proximity sensors, strain gauges, load cells, hall effect sensors, or any other suitable sensors operable to detect when the front actuator 16 and/or the rear actuator 18 are in tension or compression. In a further embodiment, the front actuator sensor 62 and the rear actuator sensor 64 are operable to detect the weight of a patient disposed on the cot 10 (e.g., when strain gauges are employed).

Referring to fig. 1-4, the movement of the roll-in cot 10 may be controlled via operator controls. Referring again to the embodiment of fig. 1, the rear end 19 may include operator controls for boarding the cot 10. As used herein, the operator controls are components used by the operator in loading and unloading the cot 10 by controlling the front legs 20, the rear legs 40, and the support frame 12. Referring to fig. 2, the operator controls may include one or more hand controls 57 (e.g., buttons on a telescoping handle) disposed on the rear end 19 of the roll-in cot 10. In addition, the operator controls may include a control box 50 provided on the rear end 19 of the roll-in cot 10, which is used by the cot to switch from a default stand-alone mode and a synchronized or "sync" mode. The control box 50 may include one or more buttons 54, 56 that are provided in the cot in a synchronized mode so that the front and rear legs 20, 40 can be raised and lowered simultaneously. In a particular embodiment, the synchronization mode may be only temporary, and the operation of the cot will return to the default mode after a period of time, for example, after about 30 seconds. In another embodiment, a synchronized mode may be employed in loading and/or unloading the cot 10. While various positions are contemplated, the control box may be disposed between the handles on the rear end 19.

As an alternative to the hand control embodiment, the control box 50 may also include components that can be used to raise and lower the roll-in cot 10. In one embodiment, the component is a toggle switch 52 that can raise (+) or lower (-) the cot. Other buttons, switches or knobs are also suitable. Since the sensors are incorporated into the upper truck bed 10, as explained in greater detail herein, the toggle switch 52 can be used to control the front or rear legs 20, 40, which can be operated to raise, lower, retract or release depending on the position of the upper truck bed 10. In one embodiment, the toggle switch is analog (i.e., the analog switch pressure and/or displacement is proportional to the actuation speed). The operator controls may include visual display members 58 configured to inform an operator whether the front and rear actuators 16, 18 are activated or deactivated and thus may be raised, lowered, retracted, or released. While the operator controls are provided at the rear end 19 of the roll-in cot 10 in this embodiment, it is also contemplated that the operator controls may be positioned at alternative locations on the support frame 12, such as on the front end 17 or sides of the support frame 12. In other embodiments, the operator controls may be located in a removably attachable wireless remote controller that is capable of controlling the roll-in cot 10 without being physically attached to the roll-in cot 10.

In other embodiments, shown in fig. 4, the roll-in cot 10 may further include a light strip 140 configured to illuminate the roll-in cot 10 in low light or low visibility environments. The light strip 140 may include LEDs, light bulbs, phosphorescent materials, or combinations thereof. The light strip 140 may be triggered by a sensor that detects low light or low visibility environments. In addition, the cot may also include an on/off button or switch for the light strip 140. While the light strip 140 is positioned along the side of the support frame 12 in the embodiment of fig. 4, it is contemplated that the light strip 140 can be disposed on the front and/or rear legs 20, 40 and various other locations on the roll-in cot 10. Further, it is noted that the light strip 140 may be used as an emergency warning light similar to an ambulance emergency light. Such emergency warning lights are configured to sequence the warning lights to draw attention to the emergency warning lights and mitigate hazards such as sensitive epilepsy, glare, and phototaxis.

Turning now to the embodiment of the simultaneous actuation boarding cot 10, the cot of fig. 4 is shown extended so that the front actuator sensors 62 and the rear actuator sensors 64 detect that the front actuator 16 and the rear actuator 18 are under compression, i.e., the front leg 20 and the rear leg 40 are in contact with the lower surface and are loaded. Both the front and rear actuators 16 and 18 are active when the front and rear actuator sensors 62, 64 detect that both the front and rear actuators 16, 18, respectively, are under compression and can be raised or lowered (as shown in fig. 2) by an operator using operator controls (e.g., "-" lower, "+" raise).

Referring collectively to fig. 5A-5C, an embodiment of the roll-in cot 10 is schematically illustrated as being raised (fig. 5A-5C) or lowered (fig. 5C-5A) via simultaneous actuation (note that for clarity, the front actuator 16 and the rear actuator 18 are not shown in fig. 5A-5C). In the illustrated embodiment, the roll-in cot 10 includes a support frame 12 in sliding engagement with a pair of front legs 20 and a pair of rear legs 40. Each front leg 20 is rotatably coupled to a front hinge member 24 that is rotatably coupled to the support frame 12 (e.g., via carriage members 28, 48 (fig. 8)). Each rear leg 40 is rotatably coupled to a rear hinge member 44 that is rotatably coupled to the support frame 12. In the illustrated embodiment, the front hinge member 24 is rotatably coupled toward the front end 17 of the support frame 12 and the rear hinge member 44 is rotatably coupled toward the rear end 19 of the support frame 12.

Fig. 5A shows the roll-in cot 10 in a lowermost transport position (e.g., the rear wheels 46 and the front wheels 26 are in contact with a surface, the front legs 20 are slidingly engaged with the support frame 12 such that the front legs 20 contact a portion of the support frame 12 toward the rear end 19, and the rear legs 40 are slidingly engaged with the support frame 12 such that the rear legs 40 contact a portion of the support frame 12 toward the front end 17). Fig. 5B shows the roll-in cot 10 in an intermediate transport position, i.e., the front 20 and rear 40 legs are in an intermediate transport position along the support frame 12. Fig. 5C shows the roll-on cot 10 in the highest transport position, i.e., the front and rear legs 20, 40 are positioned along the support frame 12 such that the front loading wheels 70 are at a maximum desired height, which may be set to a height sufficient to load the cot, as described in greater detail herein.

The embodiments described herein may be used to lift a patient from a position below a transport in preparation for loading the patient into the transport (e.g., from the ground above a loading surface of an ambulance). Specifically, the roll-in cot 10 may be raised from a lowermost transport position (fig. 5A) to an intermediate transport position (fig. 5B) or an uppermost transport position (fig. 5C) by simultaneously actuating the front and rear legs 20, 40 and sliding them along the support frame 12. When raised, actuation causes the front leg to slide toward the front end 17 and rotate about the front hinge member 24, causing the rear leg 40 to slide toward the rear end 19 and rotate about the rear hinge member 44. Specifically, the user may interact with the control box 50 (fig. 2) and provide an input (e.g., by pressing "+" on toggle switch 52) indicating a desire to raise the roll-in cot 10. The pick-up cot 10 is raised from its current position (e.g., the lowest transport position or an intermediate transport position) until it reaches the highest transport position. When the highest transport position is reached, the actuation may be automatically stopped, i.e. the higher the lift of the lift cot 10 requires additional input. The input may be provided to the lift cot 10 and/or the control box 50 in any manner, such as electronically, audibly, or manually.

The roll-in cot 10 may be lowered from the intermediate transport position (fig. 5B) or the highest transport position (fig. 5C) to the lowest transport position (fig. 5A) by simultaneously actuating the front and rear legs 20, 40 and sliding them along the support frame 12. Specifically, when lowered, actuation causes the front legs to slide toward the rear end 19 and rotate about the front hinge members 24, causing the rear legs 40 to slide toward the front end 17 and rotate about the rear hinge members 44. For example, the user may provide an input indicating a desire to lower the roll-in cot 10 (e.g., by pressing a "-" on the toggle switch 52). Upon receiving this input, the pick-up cot 10 is lowered from its current position (e.g., the highest transport position or an intermediate transport position) until it reaches the lowest transport position. Once the pick-up cot 10 reaches its lowest elevation (e.g., lowest transport position), actuation may automatically stop. In some embodiments, control box 50 (fig. 1) provides a visual indication that front legs 20 and rear legs 40 are active during movement.

In one embodiment, when the roll-in cot 10 is in the highest transport position (fig. 5C), the front leg 20 contacts the support frame 12 at the front loading indicia 221 and the rear leg 40 contacts the support frame 12 at the rear loading indicia 241. Although the front loading indicium 221 and the rear loading indicium 241 are shown in fig. 5C as being located near the middle of the support frame 12, further embodiments contemplate the front loading indicium 221 and the rear loading indicium 241 being located at any position along the support frame 12. For example, the top transport position may be set by actuating the roll-in cot 10 to a desired height and providing an input indicating that it is desired to set the top transport position (e.g., pressing and holding "+" and "-" on the toggle switch 52 simultaneously for 10 seconds).

In another embodiment, at any time the lift cot 10 is raised above the maximum transport position for a set period of time (e.g., 30 seconds), the control box 50 provides an indication that the lift cot 10 has exceeded the maximum transport position and that the lift cot 10 needs to be lowered. The indication may be visual, audible, electronic, or a combination thereof.

When the roll-in cot 10 is in the lowermost transport position (fig. 5A), the front leg 20 may contact the support frame 12 at a front flat indicia 220 located near the rear end 19 of the support frame 12, and the rear leg 40 may contact the support frame 12 at a rear flat indicia 240 located near the front end 17 of the support frame 12. Furthermore, it is noted that the term "mark" as used herein refers to a position along the support frame 12 which corresponds to a mechanical or electrical stop, for example an obstacle in a channel formed in the lateral side member 15, a locking mechanism or a stop controlled by a servo mechanism.

The front actuator 16 is operable to raise or lower the front end 17 of the support frame 12 independently of the rear actuator 18. The rear actuator 18 is operable to raise or lower the rear end 19 of the support frame 12 independently of the front actuator 16. The roll-in cot 10 is capable of maintaining the support frame 12 horizontal or substantially horizontal by independently raising either the front end 17 or the rear end 19 as the roll-in cot 10 moves over uneven surfaces, such as stairs or ramps. Specifically, if one of the front or rear legs 20, 40 is under tension, the set of legs that are not in contact with the surface (i.e., the set of legs under tension) are activated by the roll-in cot 10 (e.g., by moving the roll-in cot 10 off the curb). Other embodiments of the roll-in cot 10 can operate to automatically level. For example, if the rear end 19 is lower than the front end 17, pressing "+" on the toggle switch 52 raises the rear end 19 to level before raising the roll-on cot 10, and pressing "-" on the toggle switch 52 lowers the front end 17 to level before lowering the roll-on cot 10.

In one embodiment, as shown in fig. 2, the roll-in cot 10 receives a first load signal from the front actuator sensor 62 indicative of a first force acting on the front actuator 16 and receives a second load signal from the front actuator sensor 62 indicative of a second force acting on the rear actuator 18. The first and second load signals may be processed by logic executed by the control box 50 to determine the response of the lift truck bed 10 to inputs received by the lift truck bed 10. Specifically, user input may be entered into the control box 50. The user input is received as a control signal indicating a command to change the height of the getting-on cot 10 through the control box 50. In general, when the first load signal represents tension and the second load signal represents compression, the front actuator actuates the front legs 20 while the rear actuator 18 remains substantially static (e.g., does not actuate). Thus, when only the first load signal indicates a tension state, the front leg 20 may be raised by pressing a "-" on the toggle switch 52 and/or lowered by pressing a "+" on the toggle switch 52. In general, when the second load signal represents tension and the first load signal represents compression, the rear actuator 18 actuates the rear leg 40 while the front actuator 16 remains substantially static (e.g., does not actuate). Thus, when only the second load signal indicates a tension state, the rear leg 40 may be raised by pressing "-" on the toggle switch 52 and/or lowered by pressing "+" on the toggle switch 52. In some embodiments, the actuator may be actuated more slowly (i.e., slowly activated) at the initial motion before being actuated more quickly to mitigate rapid jostling of the support frame 12.

Referring collectively to fig. 5C-6E, independent actuation may be used by embodiments described herein to load a patient into a transport (note that the front actuator 16 and the rear actuator 18 are not shown in fig. 5C-6E for clarity). Specifically, the upper deck cot 10 may be loaded onto the loading surface 500 according to the process described below. First, the pick-up cot 10 may be set into the highest transport position (fig. 5C), or any position in which the front loading wheels 70 are located at a higher elevation than the loading surface 500. When the lift cot 10 is loaded onto the loading surface 500, the lift cot 10 may be raised via the front and rear actuators 16 and 18 to ensure that the front loading wheels 70 are disposed on the loading surface 500.

As shown in fig. 6A, the front loading wheels 70 are on the loading surface 500. In one embodiment, after the loading wheels contact the loading surface 500, the pair of front legs 20 may be actuated with the front actuator 16 because the front end 17 is above the loading surface 500. As shown in fig. 6A and 6B, the middle portion of the upper deck cot 10 is away from the loading surface 500 (i.e., a sufficiently large portion of the upper deck cot 10 has not yet been loaded beyond the loading edge 502 so that a majority of the weight of the upper deck cot 10 may be suspended and supported by the wheels 70, 26, and/or 30). When the front loading wheels are fully loaded, the lift cot 10 may remain level with a reduced amount of force. Additionally, in such a position, the front actuator 16 is under tension and the rear actuator 18 is under compression. Thus, for example, if "-" on toggle switch 52 is enabled, front leg 20 is raised (fig. 6B). In one embodiment, the operation of the front and rear actuators 16, 18 is dependent on the position of the upper cot after the front leg 20 has been raised sufficiently to trigger the loading state. In some embodiments, a visual indication is provided on the visual display component 58 of the control box 50 with the front leg 20 raised (fig. 2). The visual indication may be color-coded (e.g., green for enabled legs and red for non-enabled legs). The front actuator 16 may automatically cease operation when the front leg 20 has been fully retracted. Further, it is noted that during retraction of the front legs 20, the front actuator sensor 62 may detect tension, at which point the front actuator 16 may raise the front legs 20 at a higher rate (e.g., fully retracted within about 2 seconds).

After the front legs 20 have been retracted, the roll-in cot 10 may be pushed forward until the intermediate loading wheels 30 have been loaded onto the loading surface 500 (fig. 6C). As shown in fig. 6C, the front end portion 17 and the middle portion of the roll-on cot 10 are above the loading surface 500. Thus, the pair of rear legs 40 can be retracted using the rear actuator 18. In particular, the ultrasonic sensor may be positioned to detect when the intermediate portion is above the loading surface 500. During the loading state, the rear actuator may be actuated when the intermediate portion is above the loading surface 500 (e.g., the angle of the front and rear legs 20, 40 is greater than the loading state angle). In one embodiment, an indication (e.g., an audible beep may be provided) may be provided by the control box 50 (fig. 2) when the intermediate loading wheel 30 is sufficiently beyond the loading edge 502 to allow the rear legs 40 to actuate.

It is noted that when any portion of the roll-in cot 10 that may be used as a fulcrum is sufficiently beyond the loading edge 502, the middle portion of the roll-in cot 10 is above the loading surface 500 such that the rear legs 40 may be retracted, the amount of force required to lift the rear end 19 is reduced (e.g., less than half the weight of the roll-in cot 10 that may be loaded that needs to be supported at the rear end 19). Further, it is noted that the detection of the position of the roll-in cot 10 may be accomplished by sensors located on the roll-in cot 10 and/or sensors located on or near the loading surface 500. For example, an ambulance may have sensors that detect the positioning of the roll-in cot 10 relative to the loading surface 500 and/or the loading edge 502 and a communication device that communicates information to the roll-in cot 10.

Referring to fig. 6D, after the rear leg 40 is retracted, the roll-in cot 10 may be pushed forward. In one embodiment, during rear leg retraction, the rear actuator sensor 64 may detect that the rear legs 40 are unloaded, at which point the rear actuator 18 may raise the rear legs 40 at a higher speed. With the rear leg 40 fully retracted, the rear actuator 18 may automatically cease operation. In one embodiment, when the cot 10 is loaded sufficiently beyond the loading edge 502, an indication may be provided by the control box 50 (fig. 2) (e.g., fully loaded or loaded such that the rear actuator is beyond the loading edge 502).

Once the cot is loaded onto the loading surface (fig. 6E), the front and rear actuators 16, 18 may be deactivated by lockingly coupling to the ambulance. Both the ambulance and the roll-on cot 10 may be fitted with components suitable for coupling, for example, male-female connectors. Additionally, the getting-on cot 10 may include a sensor that registers when the cot is fully disposed in the ambulance and sends a signal that causes the actuators 16, 18 to lock. In another embodiment, the upper cot 10 may be connected to cot fasteners to lock the actuators 16, 18, and further coupled to the power system of the ambulance, which charges the upper cot 10. A commercial example of such an ambulance charging system is the Integrated Charging System (ICS) manufactured by Ferno-Washington ltd.

Referring collectively to fig. 6A-6E, as described above, independent actuation may be used by embodiments described herein to unload the upper deck cot 10 from the loading surface 500. Specifically, the upper deck cot 10 may be unlocked from the fasteners and urged toward the loading edge 502 (fig. 6E-6D). When the rear wheels 46 are released from the loading surface 500 (fig. 6D), the rear actuator sensors 64 detect that the rear legs 40 are unloaded and allow the rear legs 40 to lower. In some embodiments, the rear legs 40 may be prevented from lowering, for example, if the sensors detect that the cot is not in the correct position (e.g., the rear wheels 46 are above the loading surface 500, or the intermediate loading wheels 30 are away from the loading edge 502). In one embodiment, an indication may be provided by the control box 50 (fig. 2) when the rear actuator 18 is activated (e.g., the intermediate loading wheels 30 are near the loading edge 502 and/or the rear actuator sensors 64 detect tension).

When the roll-in cot 10 is properly positioned relative to the loading edge 502, the rear legs 40 may be extended (fig. 6C). For example, rear leg 40 may be extended by pressing a "+" on toggle switch 52. In one embodiment, with the rear leg 40 lowered, a visual indication is provided on a visual display component 58 (fig. 2) of the control box 50. For example, a visual indication may be provided when the roll-in cot 10 is in the stowed state and the rear legs 40 and/or the front legs 20 are actuated. Such a visual indication may generate a signal during actuation that the roll-in cot should not move (e.g., pull, push, or roll). When the rear legs 40 contact the floor (fig. 6C), the rear legs 40 become loaded and the rear actuator sensors 64 deactivate the rear actuators 18.

When the sensor detects that the front leg 20 is clear of the loading surface 500 (fig. 6B), the front actuator 16 is activated. In one embodiment, the indication may be provided by the control box 50 (fig. 2) when the intermediate loading wheels 30 are at the loading edge 502. The front leg 20 extends until the front leg 20 contacts the floor (fig. 6A). For example, front leg 20 may be extended by pressing a "+" on toggle switch 52. In one embodiment, a visual indication is provided on the visual display component 58 (fig. 2) of the control box 50 with the front legs 20 lowered.

Referring back to fig. 4 and 12, in embodiments where the hook engagement lever 80 is operable to engage a loading surface hook 550 on the loading surface 500, the hook engagement lever 80 is disengaged prior to unloading the upper cot 10. For example, the hook engagement lever 80 may be rotated to clear the loading surface hook 550. Alternatively, the roll-in cot 10 may be raised from the position shown in fig. 4 such that the hook engagement rod 80 clears the loading surface hook 550.

It should now be appreciated that by coupling a support surface, such as a patient support surface, to a support frame, the embodiments described herein may be used to transport patients of various sizes. The roll-in cot includes a wheel alignment mechanism incorporated into the front leg that controls the vertical orientation of at least one front wheel. The wheel alignment mechanism includes at least one shock absorber that absorbs an impact load applied to at least one front wheel.

It is also noted that terms such as "preferably," "substantially," "commonly," and "typically" are not utilized herein to limit the scope of the claimed embodiments, nor are they intended to imply that certain features are critical, essential, or even important to the structure or function of the claimed embodiments. Rather, these terms are merely intended to highlight alternative or additional features that may or may not be utilized in a particular embodiment of the present invention.

For the purposes of describing and defining the present invention it is also noted that the term "substantially" is utilized herein to represent the inherent degree of uncertainty that may be attributed to any quantitative comparison, value, measurement, or other representation. The term "substantially" is also utilized herein to represent the degree by which a quantitative representation may vary from a stated reference without resulting in a change in the basic function of the subject matter at issue.

While reference has been made to specific embodiments, it will be understood that various modifications and changes may be made without departing from the scope of the invention as defined in the appended claims. More specifically, although certain aspects of the present invention are identified herein as preferred or particularly advantageous, it is contemplated that the present invention is not limited to these preferred aspects of any particular embodiment.

Claims (13)

1. A get-on simple bed, comprising:

a support frame;

a first pair of legs pivotably and slidably coupled to a support frame;

a first pair of hinge members, each hinge member pivotably coupled to a support frame and pivotably coupled to one of the first pair of legs;

a first wheel link pivotably coupled to the first pair of legs;

a wheel alignment mechanism incorporated into at least one of the first pair of legs, the wheel alignment mechanism comprising: a timing chain coupled to a first wheel linkage and one of the first pair of hinge members; a first hub coupled to one of the first pair of hinge members; and a second hub coupled to the first wheel connection, wherein the timing chain is coupled to the first hub and the second hub to transfer relative rotation of the first pair of hinge members to the first wheel connection; and

a chain tensioner coupled to one of the first pair of legs, the chain tensioner contacting the timing chain and increasing a path length of the timing chain between the first hub and the second hub, wherein:

the first pair of legs and the first pair of hinge members pivot relative to each other in a relative angular rotation ratio;

a wheel alignment mechanism rotates the first wheel link relative to the first pair of legs at a reduction ratio; and is

The relative angular rotation ratio of the first pair of legs and the first pair of hinge members is inversely proportional to the reduction ratio of the wheel alignment mechanism,

wherein the timing chain includes a plurality of links coupled to each other with pins, the links being rotatable relative to the pins, and a plurality of attachment plates coupled to the plurality of links of the timing chain, the plurality of attachment plates being rigidly coupled to at least one of the first wheel link or the first pair of hinge members.

2. The roll-on cot of claim 1, further comprising:

a second pair of legs pivotably and slidably coupled to the support frame;

a second pair of hinge members, each hinge member pivotably coupled to the support frame and pivotably coupled to one of the second pair of legs;

a second wheel linkage pivotably coupled to the second pair of legs; and

a second wheel alignment mechanism incorporated into at least one of the second pair of legs, the second wheel alignment mechanism including a timing chain coupled to one of a second wheel linkage and the second pair of hinge members, wherein:

said second pair of legs and said second pair of hinge members pivot relative to each other in a relative angular rotation ratio;

a second wheel alignment mechanism rotates a second wheel link relative to the second pair of legs at a reduction ratio; and is

The relative angular rotation ratio of the second pair of legs and the second pair of hinge members is inversely proportional to the reduction ratio of the second wheel alignment mechanism.

3. The roll-in cot of claim 1, wherein the diameter of the first hub is less than the diameter of the second hub, and the diameters of the first hub and the second hub define a reduction ratio of the wheel alignment mechanism.

4. The roll-in cot of claim 1, wherein the product of the relative angular rotation ratio and the reduction ratio is within 30%.

5. The roll-in cot of claim 1, further comprising at least one idler roller coupled to one of the first pair of legs, the at least one idler roller positioned to contact and maintain the timing chain in the first planar orientation and the second planar orientation.

6. A get-on simple bed, comprising:

a support frame;

a first pair of legs pivotably coupled to a support frame;

a first pair of hinge members, each hinge member pivotably coupled to a support frame and pivotably coupled to one of the first pair of legs;

a first wheel link pivotably coupled to the first pair of legs; and

a wheel alignment mechanism incorporated into at least one of the first pair of legs, the wheel alignment mechanism comprising a timing chain, a first hub coupled with one of the first pair of hinge members, and a second hub coupled with a first wheel connection, wherein the timing chain comprises a plurality of links coupled to one another with pins, the links being rotatable relative to the pins, and a plurality of attachment plates coupled to the plurality of links of the timing chain, the plurality of attachment plates being rigidly coupled to at least one of the first wheel connection or the first pair of hinge members, wherein:

one of the first pair of hinge members or the first pair of legs is slidably coupled to a support frame;

the first pair of legs and the first pair of hinge members pivot relative to each other in a relative angular rotation ratio;

a timing chain is coupled to the first hub and the second hub and transmits relative rotation of the first pair of hinge members to the first wheel connection;

a wheel alignment mechanism rotates the first wheel link relative to the first pair of legs at a reduction ratio; and is

The relative angular rotation ratio of the first pair of legs and the first pair of hinge members is inversely proportional to the reduction ratio of the wheel alignment mechanism.

7. The roll-in cot of claim 6, wherein the diameter of the first hub is less than the diameter of the second hub, and the diameters of the first hub and the second hub define a reduction ratio of the wheel alignment mechanism.

8. The roll-in cot of claim 6, wherein the product of the relative angular rotation ratio and the reduction ratio is within 30%.

9. A get-on simple bed, comprising:

a support frame;

a first pair of legs pivotably and slidably coupled to a support frame;

a first pair of hinge members, each hinge member pivotably coupled to a support frame and pivotably coupled to one of the first pair of legs;

a first wheel link pivotably coupled to the first pair of legs; and

a wheel alignment mechanism incorporated into at least one of the first pair of legs, the wheel alignment mechanism including a timing belt coupled to one of the first wheel connection and the first pair of hinge members and a shock absorber that selectively increases a path length of the timing belt, wherein:

the first pair of legs and the first pair of hinge members pivot relative to each other in a relative angular rotation ratio;

a wheel alignment mechanism rotates the first wheel link relative to the first pair of legs at a reduction ratio; and is

The relative angular rotation ratio of the first pair of legs and the first pair of hinge members is inversely proportional to the reduction ratio of the wheel alignment mechanism.

10. The roll-in cot of claim 9, further comprising:

a second pair of legs pivotably and slidably coupled to the support frame;

a second pair of hinge members, each hinge member pivotably coupled to the support frame and pivotably coupled to one of the second pair of legs;

a second wheel linkage pivotably coupled to the second pair of legs; and

a second wheel alignment mechanism incorporated into at least one of the second pair of legs, the second wheel alignment mechanism including a timing belt coupled to one of a second wheel connector and the second pair of hinge members, wherein:

said second pair of legs and said second pair of hinge members pivot relative to each other in a relative angular rotation ratio;

a second wheel alignment mechanism rotates a second wheel link relative to the second pair of legs at a reduction ratio; and is

The relative angular rotation ratio of the second pair of legs and the second pair of hinge members is inversely proportional to the reduction ratio of the second wheel alignment mechanism.

11. The roll-in cot of claim 9, wherein the diameter of the first hub is less than the diameter of the second hub, and the diameters of the first hub and the second hub define a reduction ratio of the wheel alignment mechanism.

12. The roll-in cot of claim 9, wherein the product of the relative angular rotation ratio and the reduction ratio is within 30%.

13. The roll-in cot of claim 9, further comprising at least one idler roller coupled to one of the first pair of legs, the at least one idler roller positioned to contact and maintain the timing belt in the first planar orientation and the second planar orientation.