USRE27183E

USRE27183E - Cylinder construction

Info

Publication number: USRE27183E
Authority: US
Priority date: 1969-07-15
Filing date: 1969-07-15
Publication date: 1971-10-12

Abstract

A FIRST CYLINDER COMPRISING INNER AND OUTER TUBULAR MEMBERS, TELESCOPICALLY JOINED FOR RELATIVE MOVEMENT BETWEEN EXTENDED AND RETRACTED POSITIONS, HAVING A FIRST PRESSURE CHAMBER FORMED WITHIN THE INNER TUBULAR MEMBER, AND A SECOND PRESSURE CHAMBER FORMED WITHIN THE RAIDAL SPACING BETWEEN THE INNER AND OUTER TUBULAR MEMBERS. A PISTON HAVING A ROD EXTENDING FROM ONE SIDE THEREOF IS SLIDABLY MOUNTED WITHIN THE FIRST PRESSURE CHAMBER IN SUCH A MANNER AS TO CAUSE RELATIVE EXTENSION OF THE INNER AND OUTER TUBULAR MEMBERS WHEN THE PISTON SIDE OPPOSITE THE ONE PISTON SIDE HAVING THE ROD EXTENDING THEREFROM IS EXPOSED TO FLUID, AND RELATIVE RETRACTION WHEN THE ONE PISTON SIDE HAVING THE ROD EXTENDING THEREFROM AND THE SECOND PRESSURE CHAMBER ARE BOTH EXPOSED TO FLUID. THE SECOND CHAMBER HAVING A FLUID ACTUATED MEMBER, THE PRESSURE RESPONSIVE AREA OF WHICH IS SUBSTANTIALLY EQUAL TO THE TRANSVERSE CROSS SECTIONAL AREA OF THE ROD, WHILE THE SUM OF THE PRESSURE RESPONSIVE AREAS OF THE FLUID ACTUATED MEMBER AND THE ONE PISTON SIDE HAVING THE ROD EXTENDING THEREFROM IS SUBSTANTIALLY EQUAL TO THE PRESSURE RESPONSIVE AREA OF THE OPPOSITE PISTON SIDE.

Description

Oct. 12, 1971 5, Q, RQSAEN Re. 27,183

CYLINDER CONSTRUCTION Original Filed Jan. 8, 1965 3 Sheets-Sheet 1 3 Sheets-Sheet 1 Original Filed Jan. 8, 1965 .N .mi

.NNN

iNVENTOR BQRJE 0. ROS'AEN` .vdi

ATTORNEYS B. O. RCSAEN CYLINDER CONSTRUCTION Oct. 12, 1971 3 Sheets-Sheet 5 Original Filed Jan. 8. 1965 www 00m 0mm ONM United States Patent O1 Reissued Oct. l2, 1971 27,183 CYLINDER CONSTRUCTION Borje O. Rosaen, 4031 Thornoaks Drive, Ann Arbor, Mich. 48104 riginal No. 3,335,642, dated Aug. 1S, 1967, Ser. No. 424,281, Jan. 8, 1965. Application for reissue July 15, 1969, Ser. No. 853,557

Int. Cl. Flllb 31/00 U.S. Cl. 92-110 14 Claims Matter enclosed in heavy brackets appears in the original patent but forms no part of this reissue specilication; matter printed in italics indicates the additions made by reissue.

ABSTRACT F THE DISCLOSURE A first fluid cylinder comprising inner ana' outer tubular members, telescopically joined for relative Inovement between extended and retracted positions, havinga Jrst pressure chamber formed within the inner tubular member, and a second pressure chamber formed within the radial spacing between the inner and outer tubular members. A piston having a rod extending from one side thereof is slidably mounted within the first pressure chamber in such a manner as to cause relative extension of the inner and outer tubular members when the piston side opposite the one piston side having the rod extending therefrom is exposed to fluid, and relative retraction when the one piston side having the rod extending therefrom and the second pressure chamber are both exposed to fluid. The second chamber having a fluid actuated member, the pressure responsive area of which is substantially equal to the transverse cross sectional area of the rod, while the sum of the pressure responsive areas of the fluid actuated member and the one piston side having the rod extending therefrom is substantially equal to the pressure responsive area of the opposite piston side.

` The present invention relates to fluid cylinders, particularly to those fluid cylinders carrying a fluid actuated two-way piston member, and more particularly to an improved construction for such cylinders including means for equalizing the effective area on each Side of the piston member.

Fluid cylinders are generally provided with a piston member movable within the cylinder in response to lluid being directed and exhausted from opposite sides of the piston member. Movement'of the piston member is transmitted through a rod connected to the piston to produce the desired mechanical Work.

A problem which has long been associated with such fluid cylinders and one which has not heretofore been satisfactorily solved is that connecting the rod member to one 'side of the piston necessarily reduces the eifective area on that side of the piston member by an amount equal to the transverse cross sectional area of the rod member. This means that with equal rate of fluid flow -being used to actuate the piston member in each direction the piston member will move in the two directions at different rates of speed. When the piston member is moving in a direction toward the rod member end of the cylinder, the larger effective area on the side of the piston member opposite the rod member Will cause the piston member to move faster in this direction than when the piston member is moving in the opposite direction.

Further, this dilference in the elfective area on opposite sides of the piston member also has the result that if equal external forces are applied in opposite directions to the end of the rod member and to the end of the cylinder housing opposite the rod member, a relative movement lice of these members lwill be produced. AS the end of the cylinder having the smaller effective area will not have sufficiently intensified pressures to act past the piston seals as compared to the pressures produced by an equivalent force acting on the other end of the cylinder, the net effect then would be to have the piston change positions upon equal external forces acting upon it. The change in volume held by a locked cylinder would be accommodated by having a vacuum created on the larger displacement 'side of the cylinder. This is an undesirable result in many applications where it is desirable that such external forces if equal have no effect on the operation oi the fluid cylinder.

Heretofore several different approaches have been utilized in attempting to solve this problem. One common approach is to provide a second rod member equal in cross sectional area and connected to the side of the piston member opposite the working rod member. Such a construction is not entirely satisfactory. Although the effective area on each side or" the piston member can be equalized in vthis manner, the resulting lluid cylinder is substantially double in length over such a iluid cylinder Without the second rod member. This is because the end of the second rod member cannot be subjected to the actuating liuid pressure and therefore the second rod member must be of sufficient length to maintain the free end unexposed throughout the entire range of movement of the piston member.

The present invention provides a fluid cylinder construction in which an area equal to the cross-sectional area of the rod member is added to the effective area of the rod member side of the piston member. This is accomplished by providing an outside tubular member encompassing the tubular member deiining the piston chamber. The outside tubular member is radially spaced from the inside tubular member and it is the cross sectional area between the tubular members which is added to the rod member side of the piston member. Although this increases the size of the fluid cylinder somewhat, the increase is in the transverse cross sectional area of the lluid cylinder and the overall length of the cylinder is left unchanged. Further, the increase is slight since the area is added at the radially outward portion of the cylinder and a slight increase in diameter in this area produces a relatively large increase in cross-sectional area.

It is an object then of the present invention to improve fluid cylinders having a piston member operable to move a rod member by providing means for increasing the effective area of the piston member on that side of the piston member connected to the rod member.

It is another object of the present invention to improve those iluid cylinders in which means are provided to equalize the elfective area on each side of the piston member by providing a construction for such cylinders in which an effective area is added to the rod member side of the piston member.

It is yet another object of the present invention to improve the aforesaid types of lluid cylinders by providing such an area increasing means in the form of an outside tubular member encompassing the tubular member delining the piston chamber and means adding the cross sectional area between the tubular members to the effective area on one side of the piston member.

Still further objects and advantages of the present invention Will readily occur to one skilled in the art to which the invention pertains upon reference to the following drawings in which like reference characters refer to like parts throughout the several views and in which:

FIG. 1 is a longitudinal cross sectional view of one preferred embodiment of the present invention.

FIG. 2 is a transverse cross sectional View taken substantially on the line 2-2 of FIG. l.

FIG. 3 is a longitudinal cross sectional view similar to `IG. 1 but illustrating another preferred embodiment of 1e present invention.

`FIG. 4 is a longitudinal cross sectional view Similar to 'IGS. 1 and 3 but illustrating yet another preferred emodiment of the present invention, and

FIG. 5 is a longitudinal cross sectional view illustratig still another preferred embodiment of the present ivention.

Now referring to the drawings for a more detailed de- :ription of the present invention, FIGS. 1 and 2 illustrate ne preferred fluid cylinder as comprising an inner tubuir member '10 defining a fluid chamber 12. The tubular iember is closed at one end by a closure member 14. `he closure member 14 is secured to the end of tubular iember 10 in a liuid tight manner such as by ywelding as idicated at 16. A mounting Ilixture 22 is formed at the xterior end of the closure member 14.

The opposite end of the tubular member 10 is closed y a guide member 24. The guide member 24 is secured the end of the tubular member 10 in a uid tight iember such as by welding as indicated at 26. The guide iember 24 is provided with an axially extending opening 8 which axially slidably receives an elongated rod memer 30. The rod member 30 extends through the opening 8 into the uid chamber 12 and is secured at its interior nd to a piston member 32. An O-ring seal 34 carried y the guide member 24 prevents lluid leakage from the uid chamber 12 along the rod member 30. The piston iember 32 axially slidably engages the inner surface of he tubular member 10 and an lO-ring seal 36 prevents fluid :akage past the piston member 32. This piston member r2 divides the fluid chamber 12 into two separated hambers 12A and 12B. The closure member 14 and he tubular member 10 are provided with a passage 18 onnecting the chamber 12A with a port member 20 arried exteriorly of the tubular member 10. A conlecting fixture 38 is carried at the exterior end of the od member 30.

The inner tubular member 10 is telescopically reeived by an outer tubular member 40. The outer tubuar member 40 is provided at one end with a radially in- /ardly extending flange portion 42 which axially slidvbly engages the outer surface of the inner tubular memrer 10. A ring member 44 is secured preferably by weldug as indicated at 46 to the exterior surface of the inier tubular member 10 at the end adjacent the guide uember 24. The flange portion 42 and the ring member i4 close the ends of an annular lluid chamber 48 formed ntermediate the inner tubular member 10 and the outer ubular member 40. O-

ring seals

50 and 52 carried by the lange portion 42 and the ring member 44 respectively rrevent fluid leakage from the chamber 48. Annularly paced ports 49 provided in the inner tubular member 0 connect the fluid chamber 12B to the annular charn- |er 48.

An end member 54 closes the end of the tubular nember 40 opposite the flange portion 42 and is prefrrably secured to the tubular member 40 as by welding .s indicated at 56. The end member 54 is provided with .n axial opening 58 which receives the rod member 30. The rod member 30 and the end member 54 are prefrably secured one to the other as by Welding as inlicated at 60.

An atmosphere chamber 62 is formed in the end of he tubular member 40 intermediate the guide member 'f4 and the end member 54 and a port 64 provided in the ubular member 44 connects the chamber 62 to atmoshere A fluid port 66 is carried by the tubular member l0 and is connected to the chamber 48 in an area adjaent the flange portion 42.

The fluid ports and 66 are adapted to be connected o a source of duid flow through a conventional 4-way 'alve or other conventional directional change means :not shown). Assuming that the mounting fixture 22 is maintained in a xed position, upon fluid being directed through the port 20 and through the passage 18 into the fluid chamber 12A and fluid being exhausted from the fluid chamber 12B through the ports 49, the chamber 48 and the fluid port 66, the piston member 32 will move axially to the right as the device is shown in FIG. l. This movement of the piston member 32 will produce a corresponding axial movement of the rod member 30, the end member 54 and the outer tubular member 40 since these members are all secured together. By connecting the fixture 38 to means to be actuated, the desired mechanical work can be produced.

Upon fluid then being exhausted from the port 20 and being directed through the port 66 to the

chambers

48 and 12, the piston member 32, the rod member 30 and the tubular member 40 will be moved to the left toward the position illustrated in FIG. l. Without the provision of the tubular member 40 and more particularly the flange portion 42, this movement would be at a higher rate of speed or would require a lesser flow rate to ob tain the same force output or to move at the same rate of speed than movement to the right. This is because the rod member 30 reduces the effective area of the piston member 32 on the rod member side of the piston member 32. However, by providing the ange portion 42 with an effective area exposed to the fluid in chamber 4S substantially equal to that of the piston member 32 lost through the connection of the rod member 30 and by connecting the tubular member 40 to the rod member 30 in the manner illustrated, an equalization of the areas producing movement of the piston member 32 is provided.

It is apparent that the particular manner in which this result is produced provides a fluid cylinder which is compact and in which it is not necessary to extend the overall length as would be necessary if a second rod member were provided. Further, a common lluid delivery means can be utilized to move the piston member in both directions and it is not necessary for the flow rate to be varied depending upon which direction the piston member is to be moved.

It is to be understood that although in describing the operation of the fluid cylinder, the fixture 22 has been described as being fixed and the -xture 38 as being the actuating lixture this could be reversed. The cylinder could be used as Well with the fixture 38 lixed and the fixture 22 being used as the actuating lixture.

FIG. 3 illustrates another preferred embodiment of the present invention substantially similar to the embodiment described above but in which only one side of the piston member is subjected to fluid. The movement in the other direction being produced entirely by the fluid acting on the ange portion of the outer tubular member.

Now referring to FIG. 3, a preferred uid cylinder is therein illustrated as comprising an inner tubular member dening a uid chamber 112. The tubular member 110 is closed at one end by a closure member 114. The closure member 114 is preferably secured in place as by Welding as indicated at 116. A mounting fixture 122 is formed at the exterior end of the closure member 114.

The opposite end of the tubular member 110 is closed by a guide member 124. The guide member 124 is secured to the end of the tubular member 110 such as by welding as indicated at 126. The guide member 124 isV provided with an axially extending opening 128 which axially slidably receives an elongated rod member 130. The rod member 130 extends through the opening 128 into the interior of the tubular member 110 and is secured at its interior end to a piston member 132. The piston member 132 axially slidably engages the inner surface of the tubular member 110 to close one end of the fluid chamber 112. The piston chamber 132 divides the uid chamber 112 into two separated chambers 112A-112B. The closure member 114 and the tubular member 110 are provided with a passage 118 connecb ing the iiuid chamber 112A with a port member 120 carried exteriorly of the tubular member 110. O-ring seal 136 carried by the piston member 132 prevents fluid leakage between the chambers 112A-112\B. A connecting fixture 138 is carried at the exterior end of the rod member 130.

The inner tubular member 110 is telescopically received by an outer tubular member 140. The outer tubular member 140 is provided at one end with a radially inwardly extending flange portion 142 which axially slidably engages the outer surface of the inner tubular member 110. A ring member 144 is secured, preferably by welding as indicated at 146, to the exterior surface of the inner tubular member 110 at the end adjacent the guide member 124. The flange portion 142 and the ring member 144 close the ends of an annular fluid chamber 148 formed intermediate the inner tubular member 110 and the outer tubular member 140. O-ring seals 150 and 152 carried by the flange portion 142 and the ring member 144 respectively prevent fluid leakage from the chamber 148. It is to be noted that unlike the embodiment described with reference to FIGS. 1-2 in the embodiment of FIG. 3, the chamber 148 is closed and there is no communication provided between the chamber 148 and the chamber 112B.

An end member 154 closes the end of the tubular member 140 opposite the flange portion 142 and is preferably secured to the tubular member 140 as by welding as indicated at 156. The end member 154 is provided with an axial opening 158 which receives the rod member 130. The rod member 130 and the end member 154 are preferably secured one to the other as by welding as indicated at 160.

An atmosphere chamber 162 is formed in the end of the tubular member 140 intermediate the guide member 124 and the end member 154. Communication between the chambers 112B and 162 is provided by a plurality of passages 163 formed in the guide member 124. A port 164 provided in the tubular member 140 connects the chamber 162 to atmosphere. A uid port 166 is carried by the tubular member 140 and is connected to the chamber 148 in an area adjacent flange portion 142.

The embodiment of FIG. 3 operates substantially as described above with reference to FIGS. l and 2 except that fluid is not directed to the interior of the tubular member 110 on the right hand side of the piston member 132. Movement of the piston member 132 to the left as seen in FIG. 3 is instead produced by fluid acting on the flange portion 142 only. Thus with a proper selection of the size of the flange portion 142 the effective area utilized to produce movement of the piston member 132 in each direction can be equalized. It is to be noted also that with a proper selection of the size of the ange portion 142 any desired difference in the rate of movement in the two directions can be produced.

FIG. 4 illustrates yet another preferred embodiment of the present invention substantially similar to the embodiments described above but with one difference over those embodiments. In the embodiments described above, the fluid ports, since they are positioned on members which move relative to each other during operation of the dervice, they must be connected to the fluid source by a flexible connection of some type. The embodiment of FIG. 4 permits rigid conduits to be connected to the uid ports since each of the ports is carried by the exterior tubular member.

Now referring to FIG. 4, another preferred fluid cylinder is therein illustrated as comprising an inner tubular member 210 defining a fluid chamber 212. The tubular member 210 is closed at one end by a closure member 214. The closure member 214 is secured to the end of the tubular member 210 in a uid tight manner such as by welding as indicated at 216. A mounting fixture 222 is formed at the exterior end of the closure member 214.

The opposite end of the tubular member 210 is closed by a guide member 224. The guide member 224 is secured to the end of the tubular member 210 in a fluid tight manner such as by welding as at 226. The guide member 224 is provided with an axially extending opening 228 which axially slidably receives an elongated rod member 236. The rod member 230 extends through the opening 228 into the iiuid chamber 212 and is secured at its interior end to a piston member 232. The piston member 232 divides the fluid chamber 212 into two separate chambers 212A and 212B. An O-ring seal 234 carried by the guide member 224 prevents uid leakage from the iiuid chamber 212B along the rod member 230. The piston member 232 axially slidably engages the inner surface of the tubular member 210 and an O-ring seal 236 prevents fluid leakage past the piston member 232. A xture 238 is carried at the exterior end of the rod member 230.

The inner tubular member 210 is telescopically received by an outer tubular member 240. The outer tubular member 240 is provided at one end with a radially inwardly extending ange portion 242 which axially slidably engages the outer surface of the tubular member 210. A ring member 244 is secured, preferably by welding as indicated at 246, to the exterior surface of the inner tubular member 210 at the end thereof adjacent the guide member 224. The flange portion 242 and the ring member 244 close the ends of an annular fluid chamber 248 formed intermediate the inner tubular member 210 and the outer tubular member 240. O-

ring seals

250 and 252 carried by the flange portion 242 and the ring member 244 respectively prevent fluid leakage from the chamber 248. Annularly spaced ports 249 provided in the inner tubular member 210 connect the fluid chamber 212B to the annular chamber 248.

An end member 254 closes the end of the tubular member 240 opposite the flange portion 242 and is preferably secured to the tubular member 240 as by Welding as indicated at 256. The end member 254 is provided with an axial opening 258 which receives the rod member 230. The rod member 230 and the end member 254 are preferably secured one to the other as by welding as indicated at 260. A fluid passage 218 extends radially through the end member 254 and axially through the rod member 230 and the piston member 232 to provide communication between a port member 220 carried by the end member 254- and the fluid chamber 212A.

An atmosphere chamber 262 is formed in the end of the tubular member 240 intermediate the guide member 224 and the end member 254 and a port 264 provided in the tubular member 240 connects the chamber 262 to atmosphere. A fluid port 266 is carried by the tubular member 240 and is connected to the chamber 248 in an area adjacent the ange portion 242.

The embodiment illustrated in FIG. 4 operates substantially as described abo've with respect to the embodiment of FIGS. 1-2 except that by positioning the uid port 220 on the end member 254, the

fluid ports

220 and 266 are maintained in fixed position relative to each other and therefore rigid conduit can be used to connect the

ports

220 and 266 to a nid source.

FIG. 5 discloses still another preferred embodiment of the present invention as comprising an inner tubular member 310 dening a uid chamber 312. The tubular member 310 is closed at one end by a closure member 314. The closure member 314 is preferably secured in place as by Welding as indicated at 316. A mounting xture 322 is formed at the exterior end of the closure member 314.

The opposite end of the tubular member 310 is closed by a guide member 324. The guide member 324 is secured to the end of the tubular member 310 in a uid tight manner such as by welding as at 326. The guide member 324 is provided with an axially extending opening 328 which axially slidably receives an elongated rod member 330. The rod member 330 extends through the opening 328 into the fluid chamber 312 and is secured at its interior nd to a piston member 332. The piston member 332 ivides the fluid chamber 312 into two separate chainers 312A and 312B. An O-ring seal 334 carried by the uide member 324 prevents fluid leakage from the fluid hamber 312B along the rod member 330. The piston member 332 axially slidably engages the inner surface of he tubular member 310 and an O-ring 336 prevents uid leakage past the piston member 332. A fixture 338 s carried at the exterior end of the rod member 330.

The inner tubular member 310 is telescopically reeived by an outer tubular member 340, The outer tubular iember 340 is provided at one end with a radially invardly extending flange portion 342 which axially slidably ngages the outer surface of the tubular member 310. A ing member 344 is secured, preferably by Welding as ndicated at 346, to the exterior surface of the inner tuular member 310 at the end thereof adjacent the guide nember 324. The flange portion 342 and the ring member '44 close the ends of an annular fluid chamber 348 ormed intermediate the inner tubular member 310 and he outer tubular member 340. O-

ring seals

350 and 352 arried by the flange portion 342 and the ring member 44 respectively prevent fluid leakage from the chamber `48. Annularly spaced ports 349 provided in the inner ubular member 310 connect the fluid chamber 312B to he annular chamber 348.

An end member 354 closes the end of the tubular member 340 opposite the flange portion 342 and is prefrably secured to the tubular member 340 as by welding s indicated at 356. The end member 354 is provided lith an axial opening 358 which receives the rod memler 330. The rod member 330 and the end member 354 .re preferably secured one to the other as by welding as ndicated at 360. A fluid passage 318 extends radially hrough the end member 354 and axially through the rod nember 330 and the piston member 332 to provide comnunication between a port member 320 carried by the nd member 354 and the fluid chamber 312A. A second luid passage 368 extends radially through the end mem- `er 354 and axially through the rod member 330 and paced from the passage 318` and intersects a radial assage 370 provided in the rod member 330 to provide ommunication between a port member 366 carried by the nd member 354 and the fluid chamber 312B.

An atmosphere chamber 362 is formed in the end of he tubular member 340 intermediate the guide member '24 and the end member 354 and a port 364 provided in he tubular member 340 connects the chamber 362 to tmosphere.

The embodiment illustrated in FIG. operates substand ially as described above and like the embodiment of ilG. 4, the

ports

320 and 366 by both being carried on he end member 354 are maintained in a fixed relative iosition and therefore rigid conduits can be used to con- .ect the

ports

320 and 366 to a lluid source.

It should be recognized that the equal relationship beween the eectve cross-sectional areas of the several lressure chambers as herenbefore described, may vary vit/1in acceptable limits due to manufacturing tolerances ustomarily encountered during the manufacture 0f such luid cylinders.

Although I have described several embodiments of my nvention, it is apparent that many other changes and modifications can be made therein without departing from he spirit of the invention as expressed by the appended laims.

I claim:

[1. A fluid cylinder comprising (a) a rst tubular member and means closing the ends of said first tubular member to define a closed fluid chamber,

(b) a piston mounted in said chamber for reciprocal movement relative to said tubular member,

(c) means for connecting said chamber to a source of fluid pressure to move said piston and said tubular member relative to one another,

(d) a rod connected to one side of said piston and movable therewith,

(e) a second tubular member telescopically received by said first tubular member and radially spaced therefrom to define a second fluid chamber.

(f) a fluid actuated member in said second chamber movable in response to an increase in fluid in said second fluid chamber and means for connecting said second -lluid chamber to said fluid pressure source to produce movement of said fluid actuated member.

(g) means connecting said fluid actuated member to said piston to produce movement thereof in response to movement of said actuated member.

(h) said fluid actuated member being operable upon an increase in fluid in said second chamber to move said piston in a direction opposite the side of said piston connected to said rod] [2. The fluid cylinder as defined in claim 1 and in which the area of said fluid actuated member exposed to fluid in said second fluid chamber is substantially equal to the transverse cross-sectional area of said rod.]

:[3` The fluid cylinder as defined in claim 1 and in which said piston has a side opposite that which is connected to said rod and which is exposed to lluid in said first fluid chamber, the area of said lluid actuated member exposed to fluid in said second `fluid chamber plus the area of said piston on the rod side thereof exposed to fluid in said first fluid chamber is substantially equal to the area of said piston exposed to fluid in said first fluid chamber on the side opposite said rod.]

[4. A fluid cylinder comprising (a) a first tubular member and means closing the ends of said first tubular member to define a first fluid chamber,

(b) a piston mounted for reciprocal movement in said chamber relative to said first tubular member,

(c) a rod member having one end connected to said piston for movement therewith and the opposite end extending exteriorly of said first fluid chamber,

(d) means for connecting said first fluid chamber on the side of said piston opposite said rod member to a source of fluid pressure to thereby produce move-r ment of said piston toward the rod member side thereof,

(e) means defining a second fluid chamber spaced concentrically around said first chamber,

(f) a `fluid actuated member in said second chamber and operable to move in one direction upon an increase in Ifluid in said second fluid chamber,

(g) means for connecting said second fluid chamber to said fluid pressure source to thereby produce movement of said fluid actuated member, and

(h) means connecting said fluid actuated member to said rod member whereby to produce movement of said piston in a direction opposite to the side of said piston connected to sai drod member upon an increase in fluid in said second chamber] [5. The fluid cylinder as defined in claim 4 and in which said first mentioned fluid connecting means comprises a passage extending through said rod member and said piston] [6. A fluid cylinder comprising (a) a rst tubular member and means closing the ends of said first tubular member to define a first fluid chamber,

(c) a rod having one end connected to said piston for movement therewith and the opposite end extending exteriorly of said first fluid chamber,

(d) means for connecting said first fluid chamber on the side of said piston opposite said rod to a source of fluid pressure to thereby produce movement of said piston toward the rod side thereof,

(f) a fluid actuated member in said second chamber and operable to move in one direction upon an increase in `fluid in said second fluid chamber,

(g) means for connecting said second fluid chamber to said rfluid pressure source to thereby produce movement of said fluid actuated member, and

(h) means connecting said fluid actuated member to said rod whereby to produce movement of said piston in a direction opposite to the side of said piston connected to said rod upon an increase in fluid in said second fluid chamber, and

(i) means connecting said fluid pressure source to the side of said piston connected to said rod] [7 The fluid cylinder as defined in claim 6 and in which the area of said fluid actuated member exposed to fluid in said second fluid chamber plus the area of said piston exposed to fluid on the rod side thereof is substantially equal to the area of said piston exposed to fluid on the side opposite said rod] [8. The fluid cylinder as defined in claim 6 and in which the area of said fluid actuated member exposed to `fluid in said second fluid chamber is substantially equal to the transverse cross-sectional area of said rod] [9. A fluid cylinder comprising:

(a) a first elongated `fluid chamber,

(b) a second fluid chamber spaced concentrically around said first yfluid chamber,

(c) a piston disposed in said first fluid chamber for reciprocal movement therein,

(d) a piston rod extending axially from one side of said piston,

(e) a source of fluid pressure connected to said first chamber on each side of said piston so as to move said piston reciprocally within said first fluid chamber,

(f) means carried by said piston rod and disposed in said second fluid chamber, and

(g) connections between said fluid pressure source and said second chamber operable to introduce fluid to said second chamber to cause said piston rod carried means to move said piston and said first chamber relative to one another in at least one direction] [10. A fluid cylinder comprising,

(a) means defining a first elongated fluid chamber,

(b) means defining a second fluid chamber spaced concentrically around said first fluid chamber,

('c) a piston disposed in said first fluid chamber for reciprocal movement therein,

(d) a piston rod extending axially from one side of said piston,

(e) means for connecting a source of fluid pressure to said lirst chamber on each side of said piston so as to move said piston reciprocally relative to said first (e) means for connecting a source of fluid pressure t0 said first chamber so as to move said piston relative to said first tubular member toward a first position within said first fluid chamber,

(f) said second tubular member having an inwardly extending flange portion at one end thereof engaging the outer surface of said first tubular member and enclosing the end of said second fluid chamber,

(g) said second tubular member being secured to said piston rod so that said piston and said second tubular member move together, and

(h) connections between said fluid pressure source and said second chamber operable to introduce fluid to said second chamber to cause said flange portion and said second tubular mem-ber to move said piston and said first tubular member relative to one another toward a position opposite to said first position] [12. A fluid cylinder comprising,

(a) an inner tubular member defining a first fluid chamber,

(b) means closing one end of said inner tubular member to thereby close one end of said first fluid chamber,

(c) means closing the opposite end of said inner tubular member to close the opposite end of said chamber,

(d) said last mentioned closing means being provided with an axial, central opening,

(e) a piston disposed in said first fluid chamber for reciprocal movement within said inner tubular member,

(f) a rod member secured to one side of said piston and extending through said opening in said closure means,

(g) means for connecting a source of fluid pressure to said first chamber on opposite sides of said piston,

(h) an outer tubular member telescopically receiving said inner tubular member and provided at one end with a radially inwardly extending flange portion axially slidably engaging the outer surface of said inner tubular member,

(i) means engaging the inner annular surface of said outer member to define a second fluid chamber concentrically disposed about said first fluid chamber and defined by the inner surface of said outer tubular member and the outer surface of said inner tubular member, said engaging means and said flange portion,

(j) said outer tubular member being secured to said rod member so that said piston and said outer tubular member move together, and

(k) means for connecting a source of fluid pressure to said second fluid chamber to cause said flange portion and said outer tubular member to move said piston and said inner tubular member relative to one another] [13. The fluid cylinder as defined in claim 12 and influid chamber,

(f) means carried by said piston rod disposed in said second fluid chamber, and

(g) connections between said fluid pressure source and said second chamber operable to introduce fluid to said second chamber to cause said piston rod carried means to move said piston and said first chamber relative to one another in at least one direction] [11. A fluid cylinder comprising,

(a) a first tubular member defining a first elongated fluid chamber,

(b) a second tubular member axially receiving said first tubular member and defining a second fluid chamber spaced concentrically around said first fluid chamber,

(c) a piston disposed in said first fluid chamber for reciprocal movement within said first tubular member,

(d) a piston rod extending axially from one side of said piston,

cluding means formed in said inner tubular member for connecting said first fluid chamber on the rod member side of said piston to said second fluid chamber] [14. A fluid cylinder comprising (a) a rst tubular member and means closing the ends of said first tubular member to define a first fluid chamber,

(d) means for connecting said first fluid chamber on the side of said piston opposite said rod member to a source of fluid pressure to thereby produce. movement of said piston toward the rod member side thereof,

(f) a fluid actuated member in said second chamber and operable to move in one direction upon an increase in fluid in said second uid chamber,

(g) means for connecting said second fluid chamber to said uid pressure source to thereby produce movement of said uid actuated member, and

(h) means connecting said uid actuated member to said rod member whereby to produce movement of said piston in a direction opposite to the side of said piston connected to said rod member upon an increase in fluid in said second lluid chamber, and

(i) said second mentioned iluid connecting means comprising a passage provided in said rod member] [15. A fluid cylinder comprising (a) a first tubular member and means closing the ends of said rst tubular member to define a first uid chamber,

(c) a rod member having one end connected to said piston for movement therewith and the opposite end extending exteriorly of said rst uid chamber,

(d) 'means for connecting said first fluid chamber on the side of said piston opposite said rod member to a source of fluid pressure to thereby produce movement of said piston toward the rod member side thereof,

(f) a fluid actuated member in said second chamber and operable to move in one direction upon an increase in uid in said second uid chamber,

(g) means for connecting said second uid chamber to said uid pressure source to thereby produce movement of said uid actuated member, and

(h) means connecting said fluid actuated member to said rod member whereby to produce movement of said piston in a direction opposite to the side of said piston connected to said rod member upon an increase in lluid in said second fluid chamber, and

(i) each of said fluid connecting means comprising a passage provided in said rod member] 16. A fluid cylinder comprising:

a first tubular member and means closing the ends of said first tubular member to define a closed fluid chamber;

a piston mounted in said chamber for reciprocal movement relative to said tubular member;

means for connecting said chamber to a source of fluid pressure to move said piston and said tubular member relative to one another;

a rod connected to one side of said piston and movable therewith;

a second tubular member telescopically received by said first tubular member and radially spaced therefrom to define a second fluid chamber;

a fluid actuated member in said second chamber connected to said second tubular member and movable in response to an increase in fluid in said second fluid chamber and means for connecting said second fluid chamber t said fluid pressure source to produce movement of said fluid actuated member, the area of said flttid actuated member exposed to the fluid in said second fluid chamber being equal to the transverse cross sectional area of said rod;

means connecting said fluid actuated member to said piston to produce movement thereof in response to movement of said actuated member; and

said fluid actuated member being operable upon an increase in fluid in said second chamber to move said piston in a direction opposite the side of said piston connected to said rod.

I7. The fluid cylinder as tlehned in claim I6, wherein :aid piston has a side opposite that which is connected to :aid rod and which is exposed to fluid in said first fluid chamber, the area of said fluid actuated member exposed to fluid in said second fluid chamber plus the area of said piston on the rod side thereof exposed to fluid in said first fluid chamber is equal to the area of said piston exposed to fluid in said first fluid chamber on the side opposite said rod.

J8. A fluid cylinder comprising.'

a first tubular member and means closing the ends of said first tubuiar member to define a first fluid chamber;

a piston mounted for reciprocal movement in said chamber relative to said first tubular member;

a rod member having one end connected to said piston for movement therewith and the opposite end extending exteriorly of said rst fluid chamber;

means for connecting said first fluid chamber on the side of said piston opposite said rod member to a source of fluid pressure to thereby produce movement of said piston toward the rod member side thereof;

means defining a second fluid chamber spaced concentrically around said first chamber;

a fluid actuated member in said second chamber connected to said means defining a second fluid Chantber and operable to move in one direction upon an increase in fluid in said second fluid chamber, the area of said fluid actuated member exposed to fluid in said said second fluid chamber being equal to the transverse cross sectional area of said rod;

means for connecting said second fluid chamber to said said fluid pressure source to thereby produce movement of said fluid actuated member;

means connecting said fluid actuated member to said rod member whereby to produce movement of said pisto-n in a direction opposite to the side of said piston connected to said rod member upon an increase in fluid in said second fluid chamber; and

means connecting said fluid pressure source to the side of said piston connected to said rod.

19. The fluid cylinder as defined in claim 18, in which the area of said fluid actuated member exposed to fluid in said second fluid chamber plus the area of said piston on the rod side thereof exposed to fluid in said first fluid chamber is equal to the area of said piston exposed to fluid within said first fluid chamber on the side opposite said ro 20. The fluid cylinder as defined in claim 19, and in which said first mentioned fluid connecting means comprises a passage extending through said rod member and said piston.

2]. A fluid cylinder comprising:

means dehning a lfirst elongated fluid chamber;

means defining a second fluid chamber spaced concentrically around said first fluid chamber;

a piston disposed in said first fluid chamber for reciprocal movement therein;

a piston rod extending axially fromi one side of said piston;

means for connecting a source of fluid pressure to said first chamber on each side of said piston so as to move said piston reciprocally relative to said first fluid chamber;

fluid actuated means connected to said means defining a second fluid chamber and carried by said piston rod disposed in said second fluid chamber; and

connections between said fluid pressure source and said second chamber operable to introduce fluid to said second chamber to cause said piston rod carried fluid actuated means to move said piston and said first chamber relative to one another in at least one direction, the area of said fluid actuated means carried by said piston rod disposed in said second fluid chamber being equal to the transverse cross sectional area of said rod.

22. The fiuid cylinder as defined in claim 21, wherein the area of said means carried by said piston rod disposed in said second fluid chamber plus tlze area of said piston on the rod side thereof exposed to fluid in said first fluid chamber is equal to the area of said piston exposed to fluid in said first chamber on the side opposite said rod.

23. A fluid cylinder comprising:

a rst tubular member defining a first elongated fluid chamber;

a second tubular member axially receiving said rst tubular member and defining a second fluid chamber spaced concentrically around said first fluid chamber;

a piston disposed in said first fluid chamber for reciprocal movement within said first tubular member;

a piston rod extending axially from one side of said piston;

means for connecting a source of fluid pressure to said first chamber so as to move said piston relative toy said first tubular member toward a first position within said first fluid chamber;

said second tubular member having an inwardly extending fluid actuated flange portion at one end thereof engaging the outer surface of said first tubular member ana' enclosing the end of said second fluid chamber;

said second tubular member being secured to said piston rod so that said piston and said second tubular member move together; and

connections between said fluid pressure source and said second chamber operable to introduce fluid to said second chamber to cause said fluid actuated flange portion and said second tubular member to move said piston and said first tubular member relative to one another toward a position opposite to said first position, the area of said fluid actuated flange exposed to the fluid in said second fluid chamber being equal to the transverse cross sectional area of said rod.

24. The fluid cylinder as defined in claim 23, wherein the area of said fluid actuated flange exposed to fluid pressure in said second fluid chamber plus the areal of said piston on the rod side thereof exposed to fluid in first fluid chamber is equal to the area of said piston exposed l to fluid in said first fluid chamber on the side opposite said rod.

25. A fiuid cylinder comprising: an inner cylinder member defining a first fluid chamber; means closing one end of said inner tubular member to thereby close one end of said first fluid chamber; means closing the opposite end of said inner tubular member to close the opposite end of said chamber; said last mentioned closing means being provided with an axial, central opening; a piston disposed in said first fluid chamber for Vreciprocal movement within said inner tubular member;

a rod member secured to one side of said piston and extending through said opening in said closure means;

means for connecting a source of fluid pressure to said first chamber on opposite sides of said piston;

an outer tubular member telscopically receiving said inner tubular member and provided at one end with a radially inwardly extending fluid actuated flange portion axially slidably engaging the outer surface of said inner tubular member;

means engaging the inner annular surface of said outer member to define a second fluid chamber concentrically disposed about said first fluid chamber and defined by the inner surface of said outer tubular member and the outer surface of said inner tubular member, said engaging means and said fluid actuated flange portion;

means securing said outer tubular member to said rod member so that said piston and said outer tubular member move together; and

means for connecting a source of fluid pressure to said second fluid chamber to cause said fluid actuated ange portion and said outer tubular member to move said piston and said inner tubular member relative to one another', the area of said inwardly extending flange portion exposed to fluid in said second fluid chamber being equal to the transverse cross sectional area of said rod, the area of said inwardly extending flange portion exposed to fluid in said sec'- ond huid chamber plus the area of said piston on the rod side thereof exposed to fluid in said first fluid chamber being equal to the area in said piston exposed to fluid in said first fluid chamber on the opposite side of said rod, and including means formed in said inner tubular member for connecting said first fluid chamber on the rod member side of said piston to said second fluid chamber.

26. A fluid cylinder comprising:

a first tubular member and means closing the ends of said first tubular member to define a first fluid chamber;

a piston mounted for reciprocal movementk in said chamber relative to said first tubular member;

a rod having one end connected to said piston for movement therewith and the opposite end extending exteriorly of said first fluid chamber;

means for connecting said first fluid chamber on the rod side of said piston to a source of #uid pressure to thereby produce movement of said piston opposite the rod side thereof;

means defining a second fiuid chamber spaced concentrically around said first chamber;

a fluid actuated member in said second chamber connected to said means defining a second fluid chamber and operable to move in one direction upon an increase in fluid in said second fluid chamber;

means for connecting said second fluid chamberto said first pressure source to thereby produce movement of said fluid actuated member, the area of said fluid actuated member exposed to fluid in said second fluid chamber being equal to the transverse cross sectional area of said rod;

means connecting said fluid actuated member to said rod member whereby toproduce movement of said piston in a direction opposite to the side of said piston connected to said rod member upon an increase in fluid in said second fluid chamber; and

said second mentioned fluid connecting means comprising a passage provided in said rod member.

27. The fluid cylinder as defined in claim Z6, wherein the area of said fluid actuated member exposed to fluid in said second fiuid chamber plus the area of said piston on the rod side thereof exposed to fluid in said first fluid chamber is equal to the area of said piston exposed to said fluid in said first fluid chamber on the side opposite said rod.

28. A fluid cylinder comprising: a first tubular member and means closing the ends of .'Jad first tubular member to define a first fluid chamer; a piston mounted for reciprocal movement in said chamber relative to said first tubular member; a rod member having one end connected to said piston for movement therewith and the opposite end extending exteriorly of said first fluid chamber; means for connecting said first fluid chamber on the side of said piston opposite said rod member to a source of fluid pressure to thereby produce movement of said piston toward the rod member side thereof;

means for connecting said first fluid chamber on the rod side of said piston to a source of fluid pressure to thereby produce movement of said piston toward the opposite side thereof;

means defining a second fluid chamber spaced concentrically around said rst chamber;

means for connecting said second fluid chamber to said fluid pressure source to thereby produce movement of said fluid actuated member, the area of said fluid actuated member exposed to fluid in said second fluid chamber being equal to the transverse cross sectional v area of said rod;

means connecting said fluid actuated member to said rod member whereby to produce movement of said piston in a direction opposite to the side of said piston connected to said rod member upon an increase in fluid increase in said second fluid chamber; and

each of said fluid connecting means comprising a passage provided in said rod member.

29. The fluid cylinder as deyned in claim 28, wherein he area of said fluid actuating member exposed tofluid n said second chamber plus the area of said piston on the Iod side of the area exposed to fluid in said )rst fluid f/zamber is equal to the area of said piston exposed to luid in said first fluid chamber on the side opposite said patent.

References Cited The following references, cited by the Examiner, are of record in the patented dile of this patent or the original UNITED STATES PATENTS 5/1880 Perkins 92-152 7/1906 Rogers 92-151 X 11/192-9 Claxton 92-108 X 2/1932 Kearney 92F52 3/1940 Onions 92-111 X 12/ 1951 Hackney 92f--61 X 5/1961 Seelof 92,-151 X 2/1962 Bowman 212-145 6/1965 Lorimer 89-37 10/1960 -Flessate et al 92-108 9/'1964 McMullen 92-117 X FOREIGN PATENTS 3/1951 France 92-107 6/1963 Germany 92-108 10/1919 Great Britain 92109 U.S. Cl. X.R.