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Publication numberUS3279324 A
Publication typeGrant
Publication dateOct 18, 1966
Filing dateMay 27, 1964
Priority dateMay 27, 1964
Publication numberUS 3279324 A, US 3279324A, US-A-3279324, US3279324 A, US3279324A
InventorsEllis Jr John T
Original AssigneeEllis Fluid Dynamics Corp
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Fluid pressure operated jack
US 3279324 A
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Description  (OCR text may contain errors)

Oct. 18, 1966 ,u. T. ELLIS, JR

FLUID PRESSURE OPERATED JACK 2 Sheets-Sheet 1 Filed May 27, 1964 363 INVENTOR.

Jam/Maw?! 1325M Oct. 18, 1966 J, T. Hus, JR 3,279,324

FLUID PRESSURE OPERATED JACK Filed May 27, 1964 2 Sheets-Sheet 2 m mm W il r I I INVENTOR. & w/mizmg, J5?

United States Patent 3,279,324 FLUID PRESSURE OPERATED JACK John T. Ellis, Jr., Chicago, HL, assignor to Ellis Fluid Dynamics Corp., Chicago, Ill., a corporation of Illinois Filed May 27, 1964, Ser. No. 370,427 1 Claim. (Cl. 9141) This invention relates to an improved construction for a jack, and more particularly to an improved inexpensive construction for a hydraulic jack in which extension of a ram of the jack from its tube is limited by a valve arrangement to eliminate locking devices in the jack construction.

Most hydraulic jacks have a significant feature and that is, they are expensive to manufacture, in view of the fact that there must be a provision for a lock in the jack to prevent the jacks ram from being expelled from its tube. Various locking devices are presently employed in jacks, and all of these devices are ponderous affairs which provide the necessary locking means by use of sheer force. That is, the construction of the device is such that the ram engages a shoulder or locking ring which prevents further movement of the ram, thereby preventing expulsion of the ram from the tube. It is readily apparent that inasmuch as the present construction of jacks is such that sheer force is used to retain the rams, the locking elements must be of substantial size relative to the remaining parts of the jack. It may be readily appreciated that substantial expense is incurred in manufacturing these locking elements, by virtue of the fact that a significant amount of material is required for the parts and a great amount of labor is necessary to manufacture the parts. It is, therefore, a principal object of the herein-disclosed invention to provide a jack construction in which movement of a ram is limited by operation of a valve which allows pressure to be relieved behind the ram when the ram reaches a certain position in order to prevent further expulsion of the ram from its tube.

It is a further object of this invention to provide an improved jack construction, in which a valve is connected to a ram in such a manner that the ram may reach the furthermost limit of its extension with a load on the ram, and the valve will be opened partially so that a balance condition may be attained whereby the ram will not move out any further but will not sink.

It is another object of the present invention to provide an improved jack construction in which the jack may be simply manufactured and assembled.

It is still another object of the instant invention to provide a jack construction which has a hydraulic fluid reservoir surrounding a ram and movement of the ram is limited by a valve connected to the ram to prevent the ram from being forced out beyond a prescribed distance.

Other objects and uses of this invention will become readily apparent to those skilled in the art upon a perusal of the following specification in light of the accompanying drawing in which:

FIGURE 1 is a cross-sectional view through a jack embodying the herein-disclosed invention;

FIGURE 2 is a cross-sectional view of a valve and a valve limit control positioned in a jack such as that shown in FIGURE 1, but in Which the valve limit control includes a telescoping rod;

FIGURE 3 is a cross-sectional view of a valve and a valve limit control which are mounted in a jack construction similar to that shown in FIGURE 1, but in which the valve has a resilient valve return mechanism to urge constantly the valve into a sealing engagement with a valve seat;

FIGURE 4 is a schematic diagram of a hydraulic circuit for a jack such as that shown in FIGURES l, 2 and 3.

FIGURE 5 is a cross-sectional view of a jack embody- 3,279,324 Patented Oct. 18, 1966 ing the present invention and having a pump and a reservoir as part of the jack; and,

FIGURE 6 is a cross-sectional view taken at to the view shown in FIGURE 5 showing a release valve for the jack.

Referring now to the drawing, and especially to FIG- URE 1, it may be seen that a hydraulic jack embodying the instant invention and indicated by numeral 10 generally consists of a substantially flat base 12 with a right circular cylindrical tube 14 having one end welded to the base. A ram 16 is sealingly and slideably mounted in tube 14. A lock 18 connected to the ram and the base prevents the ram from being pulled out completely from the base. A limit control generally indicated by numeral 20 is connected to the ram and the base to limit the movement of the ram as will be described in detail hereinafter.

The flat base includes an inlet port 22 which opens into a chamber 23 which is within the tube and between the ram and the base. The inlet port has an arm 24 providing a communicating path with the exterior of the base. An exhaust port 26 communicates with chamber 23 and has an exhaust arm 28 which provides a flow path to the exterior of the base. The exhaust port is partially defined bya valve seat insert 30, which is a magnet. The valve seat contains an aperture 32 which forms a part of the exhaust port.

As was mentioned above, the tube 14 is a right circular cylindrical tube, and the axis of the tube is aligned with the center of the exhaust port 26. The construction of the tube is simplicity itself, inasmuch as it is smooth on the inside, and no machining is required other than to provide a smooth interior surface.

The ram is sealingly and slideably mounted in the tube. The ram has an annular packing recess 34 on its lower portion, and a locking ring groove 36 is also formed adjacent to the bottom of the ram. An elongated right circular axial aperture 38 is formed in the central part of the ram. The axis of the axial aperture is coincidental with the axis of the tube for reasons which will become apparent hereinafter. The axial aperture has a ring groove 40 formed therein. A conventional V-packing 42 is positioned in recess 34, and a lock ring 44 is mounted in groove 36 to hold the packing in place. This packing 42 cooperates with the interior wall of tube 14 in a conventional manner to provide a seal between the tube and the ram.

The limit control is connected to the ram and a portion of the control is positioned in the axial aperture 38. The limit control includes a rod head 46 which has a plurality of bleed holes 48 contained therein which allow hydraulic fluid to pass freely through the rod head. The rod head has a diameter slightly less than the diameter of the axial aperture so that the rod head is guided by the ram to keep the rod head aligned with the axis of the ram. A rod plate 50 is also mounted in the axial aperture 38, which rod plate also contains a pluralitv of vent holes 52 to allow hydraulic fluid to flow freely therethrough. The rod plate is held in position by a snap ring 54 which is positioned in groove 40, to prevent the plate from being pulled out of the axial aperture and away from the ram. A rigid elongated rod 56 has one end secured to the rod head, and it freely passes through the rod plate. Attached to the other end of the rod is a ball valve 58 which, in this instance, is made of a carbon steel, though any suitable material which is attracted by a magnet may be used. The ball valve is seatable in the valve seat insert to control the flow of hydraulic fluid through the aperture 32 and, thus, through the exhaust port 26.

In order to prevent the ram from being pulled out of the tube during handling, the lock 18 is attached to the ram and the base. The ram has an ear fixed to its upper edge and a link 62 is pivotedly connected to the car 60. A base car 64 is fixed to the base and a second link 66 is pivotedly connected to the second car. The links 62 and '66 are connected by a pivot 68. "It maybe appreciated that as the ram is expelled from the tube, the links are extended to allow free expulsion of the ram. The ram is limited in its extension during operation by the operation of the limit control, but the lock prevents withdrawal of the ram from the tube by an exterior force.

Looking now to FIGURE 4, which shows a circuit diagram for the jack 10, it may be seen how the instant jack is operated. A line 70 is connected to one end to the base at arm 24. The line 70 is also connected to an inlet valve 72 which is connected to a pump 74 through a. line 76. The line 70 is also connected to a release valve 78 which is in turn connected to a reservoir 80 through a line 82. The arm 28 is connected to a line 84 which communicates with the reservoir 80. It may be appreciated that the lines, valves, pump and reservoir are well known elements. Therefore, these elements have been shown only schematically in this instance. I

In operation, as is conventional, a load is placed on top of the ram. In order to expel ram 16 from tube 14 to raise the load, pump 74 is placed into operation by a suitable prime mover which is not shown herein. Hydraulic fluid is drawn from reservoir 80 to the pump. When valve 72 is opened and valve 78 is closed, hydraulic fluid under pressure flows through line 76 to line 70 and then int-o arm 24 of inlet port 22. The fluid then flows into chamber 23 through the inlet port. It may be readily appreciated that the pressure of the fluid develops a force on the ram to expel the mm from the tube. In the event that it is desired to hold the load at a given height, the load may be maintained at that height by closing the valve 72 and then there is no further need of pump 74. In order to release the load, the valve 78 is opened, and fluid is expelled through port 22 into line 70 and then to reser-- voir 80 by line 82. a When the ram is expelled to its limit, the limit control comes into operation. As the ram approaches its outer limit out of the tube, the rod head approaches the rod plate. It should be noted that during the operation of the ram, the rod head is moving relative to the ram, and

hydraulic fluid is vented constantly through the vents 48 Furthermore, fluid trapped between the rod plate and the rod head is vented through the vents in the rod head as well as in the rod plate. When the ram moves out a suflicient distance, the rod plate engages the rod head to raise the rod head, thereby unseating the ball valve 58 from valve seat 30. As soon as the ball valve is unseated, thepressure in chamber 23 is relieved, whereby the ram ceases moving outward of the tube. It may be appreciated that a position may be achieved wherein the ball is unseated sufl'lciently to create a leak so that the pressure in chainber 23 is such that the force pushing the ram out of the tube equals the load on the ram, and a steady state oc-' curs, whereby the ram moves in neither direction.

The construction of the instant jack provides a safety measure in that the ball valve is kept on the seat except when pulled oit by the ram. Inasmuch as the valve seat is'a magnet, it' attracts the ball for proper seating at all times. It should also be noted that the cooperation of the rod head with the ram and the rod plate with the rod provides a guide for the rod to keep the ball positioned in the seat. Thus, even if the jack were dropped, or in some other way mishandled, the ball would not become unseated, so that the jack would no longer be eflective.

However, if there were damage, it would fail safe in that the ram would not be extended.

It is readily apparent that the instant construction provides a simple and inexpensive means for limiting the travel of the ram under pressure. As was mentioned above, lock 18 prevents the ram from being pulled out of the tube by a mechanical force, such as, during handling.

It should also be noted that the ear 60 provides an additional advantage, in that it prevents the ram from bottoming'on the base, because it holds the'base up slightly above the tube.

It may be readily appreciated that if a particularly long ram were used, the axial aperture would, of necessity, be a deep. cut. In order to provide a shorter axial aperture, a telescoping limit control is provided. Looking now to FIGURE 2, a telescoping limit control is shown therein. The remainder of the jack is identical to that shown in FIGURE 1, and, therefore, that portion of the jack is not shown in view of the fact that it would be repetitious. A flat base 112 includes an inlet port 122 with an arm 124. The base also has an exhaust port 126 with an arm 128. The exhaust port has a valve seat 130 formed therein with an aperture 132 defined by the valve seat. A ram 116 which is sealingly and slideably mounted in a tube which is not shown, but is identical to tube 14, has an axial aperture 138 contained therein. A ring groove 140 is formed in the aperture.

The limit control 120 includes a tubulor rod 142 which has an integral annular external flange 144 formed therein, and cooperative with the ram. A lock ring 146 is mounted in the interior of the tubular rod adjacent to the annular flange. An interior annular flange 147 is formed integral with the other end of the tubular rod. A rod head 148 is slideably mounted in the tubular rod. A rod plate 150 is mounted in the axial aperture, and held in position by a snap ring 152 which is positioned in groove 140. A rigid rod 156 has one end fixed to the rod head 148, and the opposite end of the rod is fixed to a ball valve 158 which is identical to ball valve 58. Ball valve 158 is positionable in seat 130 to control fluid flow through the aperture 132.

It may be appreciated that as the ram 116 moves away from base 112 by operation of a fluid circuit such as that shown in FIGURE 4, the annular flange 144 of the tubular rod engages the plate 150. As the ram continues moving away from base 112, the rod head 148 engages the interior annular flange 147, and further movement of the ram unseats the ball valve 158 from the valve seat to allow fluid to flow through aperture 132. It is readily apparent that the operation of the jack is identical to the jack shown and described in connection with FIGURE 1,

. with the exception that the rod is telescopic and no mag hereinafter. In view of the fact that the remainder of the jack is substantially identical to that shown in FIGURE 1, a repetition of'the description will not be made herein, nor will the showing of the construction be repeated.

' Looking now to FIGURE 3, it may be seen that a base 212 has a limit control 220 connected thereto, and the 7 base includes an inlet port 222 which has an arm 224 communicating therewith. The base also includes an exhaust port 226' which has an arm 228 communicating therewith. In this instance, the exhaust port has a valve seat 230 defining a portion of the port with an aperture 232 being defined by the valve seat. On the other side of the valve seat there is an enlarged chamber 234 which opens to the bottom of the base. A sealing plug 236 is threadedly mounted in the base to seal closed the chamber A ram 216, which is identical in construction to ram 16, is sealingly and slideably mounted in a tube (which is not shown herein but is identical in construction to tube 14). The ram includes an axial aperture 238 which has a groove 240 formed therein; A rod head 246 having vents 2 48 contained therein is axially movable in the axial aperture 238. A rod plate 250 having vents 252 is held in position by a snap ring 254 which is positioned in groove 240. A rigid rod 256 has one end fixed to head 246. A ball valve 258 is fixed to the other end of the rod. The ball valve 258 is seatable in valve seat 230 in order to control the flow of fluid through aperture 232 and thereby through the exhaust port. The valve has a valve stem 260 fixed thereto, and extending in a direction opposite to rod 256. The valve stem extends through the aperture 232 and into chamber 234. A stem plate 262 is fixed to the end of the stern 260 in chamber 234. A coil spring 264 is positioned between the stem plate and the base, 'so that it constantly urges the ball valve into engagement with its seat.

It may be readily appreciated that the operation of the limit control 220 shown in FIGURE 3 is substantially identical to the limit controls shown in FIGURES 1 and 2. As the ram 216 moves away from base 212, the rod head 246 comes into engagement with rod plate 250. The continued motion of the ram away from the base causes the ball valve 258 to be unseated from valve sea-t 230 and thereby allow a reduction in pressure. It may be appreciated that as the ram moves closer to the base, the spring 264 constantly urges the ball valve into a seating position. It is, thus, readily apparent that there is no need for other guide means, and the instant arrangement allows the jack to be given more severe usage.

A further advantage of the construction shown in FIG- URE 3 is that an external lock, such as, lock 18, is not required. It may be readily appreciated that, should the ram be pulled out of the tube, the spring 264 would be compressed and the ram would be prevented from further extraction by the ooaction of the rod head with the rod plate and the stem plate and the base.

Referring now -to FIGURES 5 and 6, another jack 300 embodying the present invention is shown therein. Jack 300 generally consists of a substantially flat base 302 with a generally cylindrical tube 304 formed integral therewith. A ram 306 is sealingly and slideably mounted in the tube to provide the operative portion of the jack. A reservoir 308 surrounds the tube to provide a receptical for hydraulic fluid used in the jack. A limit control 310 connects the ram with a valve 312, which valve is connected to a pump 314 for control of fluid from the tube. A check valve 316 controls, in one direction, flow of fluid from the reservoir to valve 312. A release valve 318 is positioned in the base to control the return of fluid from the tube to the reservoir. The ram is connected to the base by means of a lock 320 to prevent the ram from being pulled out of the tube.

The base 302 has a cylindrical boss 322 formed integral therewith. As was mentioned above, the tube 304 is formed integral with the base and with the boss with an axial cylindrical ram aperture 324 formed in the tube. A flange 326 is formed integral with an upper portion of the tube for forming a portion of the reservoir.

As was mentioned above, the ram 306 is sealingly and slideably mounted in the tube 304. The ram includes a cylindrical column 328 which has an axial aperture 330 formed in its center. The upper portion of the axial aperture 330 has internal threads 332 formed therein, which mateably receive a pedestal 334 having external threads 336 which threads mate with threads 332. The pedestal has a groove 338 on its upper end to receive rotatably a head 340 which head also acts as a platform for a ram. The pedestal has a plug aperture 342 in its lower end with a plug 344 positioned therein, and a spring 346 urges the plug into engagement with the interior surface of the column to resist free rotation of the pedestal. The column also has an axial aperture 348 formed in its opposite end to receive the limit control 310. A ring groove 350 is cut into the lower end of the column and a sealing ring 352 is mounted in the ring groove to provide a seal between the column and the interior surface of the tube.

The base has a valve recess 354 formed therein with a valve seat 356 cooperating with the valve recess to define a valve port. A check valve cavity 358 is formed in the base to receive the check valve 316. A valve Seat 360 defines a portion of a port 362 which provides communicating path between the reservoir and the check valve cavity. A ball 364 is sealingly engageable with the valve seat 360 to control the flow of fluid from the reservoir. A threaded plug 366 is mounted in the base to seal closed the valve cavity. A spring 368 is positioned in the check valve cavity between the plug and ball 364 to urge constantly the ball into sealing engagement with the check valve seat 360. An elongated port 370 extends between the recess 354 and the cavity 358 to provide communicating path from the cavity to the recess.

The pump 314 includes a pump aperture 372 which is formed in the base. A pump port 374 provides a flow path from the pump aperture to the check valve cavity. A pump cylinder 376 is sealingly and slideably mounted in the pump aperture to provide the position displacement means for operation of the pump. The pump cylinder includes a sealing groove 378 with a seal 380 mounted in engagement with the base. A handle 382 has one end pivotedly connected to the cylinder through a pivot 384. The handle is also pivotedly mounted on an ear 386 which is formed integral with the base at a pivot 388. The handle is, thus, operable as a first class lever to reciprocate the pump cylinder and pump hydraulic fluid from the reservoir to the tube.

The valve 312 includes a valve body 390 which is sealingly mateable with the valve seat 356. A magnet 392 is fixed to the valve body and attracts the base to urge constantly the valve into sealing engagement with the valve seat. It may be readily appreciated that pump 314 may unseat the valve body in order to deliver fluid to the tube, but the valve body prevents fluid from returning from the tube into recess 356.

' As was mentioned above, the limit control 310 conn'ects the valve body with the ram. A rod 394has one end fixed to the valve body and a rod head 396 is fixed to the other end of the rod. An interior limit tube 39 8 slideably receives the head 396 and has an apertured bottom 400 which is engageable with the head. The interior limit tube has an outer flange 402 which is slideable in an outer limit tube 404. The outer limit tube has an interior flange 406 which is engageable with the outer flange 402. The outer limit tube has an outer limit flange 408 which is engageable with a stop ring 410. The stop ring 410 is held in position in one direction by a snap ring 412 which is mounted in a groove 414 within the axial aperture of the column.

In order to allow hydraulic fluid to be expelled from the interior of the tube, the release valve is provided. A release valve cavity 416 is formed in the base 302. A release port 418 connects the interior of the tube with the release valve cavity. A second release port 420 connects the release valve cavity with the reservoir 308. The release valve includes a release valve seat 422 which defines a portion of the release valve port 418. A tapered body 424 is sealingly engageable with the seat 422. The tapered body is connected to a threaded portion 426 which is threadedly mounted in the base to move the tapered body axially in the cavity 416. A release knob 428 is fixed to the threaded portion so that the body may be selectively engaged and disengaged with the release valve seat to control the flow of fluid through the port 418 by turning the knob to rotate the threaded portion.

The lock 320, which secures the ram to the base, and thus holds the ram within the tube, includes a lock car 430 which is formed integral with the base. A lock ring 432 is fixed to the ram, and a cable 434 has one end positioned through the ear 430 and the other end positioned through the ring 432. Balls 436 and 438 are swaged' on opposite ends of the cable to secure the cable in the ring and the ear.

The reservoir 308 includes a reservoir tube 440 which has one end in sealing engagement with the boss 332. The boss 332 has a groove 442 formed therein with a sealing ring 444 mounted in the groove 442 which ring is in sealing engagement with the interior of the reservoir tube. The flange 326 also has a sealing groove 446 formed therein with a sealing ring 448 positioned in the groove and the ring is in sealing engagement with the interior of the reservoir tube. The flange has a lock groove 450 formed therein above the sealing groove 446, and a locking ring 452 is positioned in the lock groove 450. The tube 440 has its upper end ehamfered so that the locking ring 452 engages the chamfered upper end of the tube to hold the tube securely in position between the base and the locking ring.

. When the jack 300 is operated, first the pedestal is adjusted in the column in order to place the head 340 at a proper height relative to the base. noted that the'head adjustment is made by turning the pedestal relative to the column, and the pedestal is resiliently held in position by the resilience of spring 346 holding the plunger 344 in frictional engagement with the interior of the column. 7

The ram is extended from the tube by the operation of pump 314. As the upper end of handle 382 is pushed toward the ram, cylinder 376 is withdrawn from-the pump aperture to reduce the pressure therein. Inasmuch; as reduction of thepressure causes the valve body 390 to seat more securely on valve seat 354, the only relief in the pressure is through the check valve 316. The ball 364 is unseated from seat 360 to allow hydraulic fluid to flow from reservoir 308 into the pump aperture. When cylinder. 367 is moved toward the ram, the pump acts as a positive displacement pump to seat ball 364 against valve seat 360 and to unseat valve body 390 from its valve seat against the force of magnet 392. The hydraulic fluid then flows into the space within the tube 304 to force the ram upward with its load. It may be appreciated that as the pump is operated repeatedly, the pressure is built up inside the tube to raise the ram. As the ram goes up, the limit control is extended until the outer flange 408 engages the stop ring 410, and the flange 402 engages the interior flange 406 and the head 396 engages floor 400. With the ram fully extended,

the further movement of the ram causes the valve body 390 to be disengaged from valve seat 356 so'thatwhen cylinder 376 is retracted, valve 312 does not close, and

tht hydraulic fluid simply returns to the pumpthereby preventing further extension, of the ram. Thus, the'extension of the ram is, limited at a predetermined position, that is, when the telescoping limit control is fully extended. It should be noted that the magnet 392 com stantly urges the valve body 390 into a seating engagement with its respective valve seat, thereby eliminating the necessity of a spring or other connection between the valve body and the base. i

In order to lower the ram from an extended position, it is necessary only to open the release valve 318. The

knob 438 is rotated to withdraw the tapered body 424 It should be 8 from the valve seat 422 thereby allowing fluid to'flow through the ports 418 and 420 from the interior of the tube to the reservoir. It should be noted that a load on the ram or the weight of the ram alone will cause the hydraulic fluid to be expelled from the tube and to be returned to the reservoir.

As with jack 10, the lock 320 serves to hold the ram in the tube 304. Thus, the ram may not be pulled out of the tube accidentially during handling.

Although specific embodiments of the herein-disclosed invention have been shown and described in detail herein, it is to be readily understood that those skilled in the art may make various modifications and changes without departing from the spirit and scope of the present invention. It is to be expressly understood that the instant invention is limited only by the appended claim.

What is claimed is:

A hydraulic jack of the character described comprising, in combination, a cylindrical tube, a substantially flat base sealingly fixed to the tube, said base having an inlet port communicating with the interior of said tube, said base having an exhaust port communicating with the interior of said tube, said base having a valve seat formed therein defining a portion of the exhaust port to provide -a constriction therethrough, said valve seat having its axis coincidental with the axis of the tube, a ball valve seatingly mounted on the valve seat to control the flow of fluid through the exhaust. port, a ram sealingly and.

slideably mounted in the tube, said ram having an axial aperture having its axis coincidental with the axis of the tube, a; rod plate mounted in the axial aperture, a rod head axially movable in the axial aperture and engage able with the rod plate,'a,rod having one end fixed to, the rod head and the other end fixed to the ball valve to unseat the ball valve when the ram reaches a predeter-. mined position, a stern connected to the ball valve and extending through the constricted portion of the exhaust port, a stem plate fixed to the stem, and a spring positioned between the stem plate and the valve seat to urge constantly the ball into seating engagement with:

the valve seat, whereby extension of the ram through a predetermined position unseats the ball andthe stem plate cooperates with the base to prevent the ram from being withdrawn from the tube by the cooperation of the rod head with the rod plate.

References Cited by the Examiner Jumps 12. WEST, Primary Examiner.

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US1455224 *Jul 20, 1921May 15, 1923Arthur PaoliHydraulic jack
US2414484 *Oct 1, 1945Jan 21, 1947Page Herbert EFluid operated device
US2464254 *May 5, 1944Mar 15, 1949Auto Specialties Mfg CoHydraulic jack
US2597952 *Sep 2, 1947May 27, 1952Packard Motor Car CoValve construction
US2863285 *Feb 15, 1957Dec 9, 1958Pomeroy Timothy CHydraulic jack
US2987047 *Aug 18, 1959Jun 6, 1961Horace Young DavidFluid-pressure actuated control apparatus
CA646337A *Aug 7, 1962Dover CorpAdjustable vehicle lift
GB390004A * Title not available
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US5489006 *Jul 23, 1993Feb 6, 1996Textron Inc.System and apparatus for limiting vehicle turning radius
Classifications
U.S. Classification91/41, 60/425, 91/47, 91/43
International ClassificationB66F3/42, B66F3/32, B66F3/24, B66F3/38
Cooperative ClassificationB66F3/38, B66F3/32, B66F3/42
European ClassificationB66F3/32, B66F3/42, B66F3/38
Legal Events
DateCodeEventDescription
Jun 12, 1981ASAssignment
Owner name: AUTOQUIP CORPORATION, A CORP. OF IL
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST. ASSIGNS THE ENTIRE INTEREST, NUNC PRO TUNC;ASSIGNOR:EFDYN CORPORATION, A CORP. OF ILL.;REEL/FRAME:003860/0882
Effective date: 19810609