US2629583A

US2629583A - Hydraulic jack

Info

Publication number: US2629583A
Application number: US623011A
Authority: US
Inventors: Joseph J Mueller
Original assignee: Auto Specialties Manufacturing Co
Current assignee: Auto Specialties Manufacturing Co
Priority date: 1945-10-18
Filing date: 1945-10-18
Publication date: 1953-02-24
Anticipated expiration: 1970-02-24

Description

Feb. 24, 1953 J. J. MUELLER 2,629,583

HYDRAULIC JACK Filed Oct. 18, 1945 4 Sheets-Sheet l Feb. 24, 1953 J. J. MUELLER 2,629,583

HYDRAULIC JACK Filed Oct. l8 19 45 4 Sheets-Sheet 2 Feb. 24, 1953 J. J. MUELLER HYDRAULIC JACK F lled 001:. m, 1945 4 Sheets-Sheet 4 55 INVEN'TOR.

Jgfi/d Ma ar Patented Feb. 24, 1953 HYDRAULIC JACK Joseph J. Mueller, St. Joseph, Mich, assignor to Auto Specialties Manufacturing Company, St. Joseph, Mich, a corporation of Michigan Application October 18, 1945, Serial No. 623,011

9 Claims.

This invention relates to floor jacks which generally comprise a relatively long, low chassis on wheels or rollers and include a load lifting lever pivotally mounted on the chassis and hydraulically' raised to engage and lift the load.

Among the objects of the present invention are to provide such a jack wherein the hydraulic unit is compactly arranged and disposed on the chassis; is demountable as an assembly from the chassis in a simple manner; is conveniently and compactly housed in the chassis for easy accessibility and demountability and convenience of operation; to provide a jack wherein the rain cylinder and ram are arranged in an upwardly inclined position relative to the longitudinal hori zontal axis of the chassis and in association with the lifting lever of the jack which is pivoted upon the chassis with respect to the top of the ram whereby a more direct thrust is imparted by the ram to the lifting lever to secure a more effective lift upon operation of the ram and whereby also a shorter jack body or chassis may be provided; to provide an arrangement of hydraulic unit and load lifting member wherein the high pressure pump and the ram cylinder are so related and arranged with respect to the load lifting member as to provide a generally relatively long travel for the high pressure pump piston and thereby eliminate the need for an additional speed pump for getting the load lifting member initially up to the load to be lifted; to provide a floor jack wherein the ram cylinder and ram for contacting the-load lifting member, and the high pressure pump cylinder and piston, are arranged in V formation on the chassis for compactness and improved operation, including the provision of a longer travel to the pump cylinder upon operation of the manual actuator; to provide a floor jack wherein the ram cylinder and ram. and high pressure pump cylinder and piston are arranged at a relatively acute V-shaped angle on the chassis and wherein the. pressure relief valve is disposed intermediate or between the ram cylinder and pump cylinder, and particularly wherein the pump piston and relief valve are operated by a common manual actuator; to provide a floor jack wherein the hydraulic unit is insertable in and removable from one end of the chassis and wherein the ram cylind'er and high pressure pump cylinder, and also the relief valve, are located at an angle to the longitudinal axis of the chassisand particularly JhEIBlIl the ram cylinder and pump cylinder are disposed in V-shaped formation, inclining upwardl'y from the horizontal axis of the chassis with the relief valve disposed centrally of the V-shaped space therebetween and operable from the same actuator that operates the pump pis-.

ton; to provide an improved arrangement of ram cylinder, ram and spring means for returning the ram to lowered position when the relief valve is opened; to provide an improved arrangement of pressure overload valve for returning the liquid back to the reservoir when the pressure in the ram cylinder exceeds a predetermined maximum whereby to prevent breakage; to provide an improved construction for bolting the hydraulic assembly onto the chassis; to provide an improved arrangement of alternate connection between the handle socket manual actuator and the hydraulic pump piston for actuation from both horizontal and vertical reciprocations of the actuator; to provide these and other objects of invention, as will be apparent from a perusal of the following specification when taken in connection with the accompanying drawings, where- Figure l is a perspective view of the floor jack;

Figure 2 is a view showing in perspective the various parts of the jack;

Figure 3 is a side view, partly in section, of the jack;

Figure 4 is a plan view;

Figure 5 is an enlarged sectional view of the hydraulic unit of the jack;

Figure 6 is a view of the actuating sector;

Figure 7 is a view partly in section, looking from the front of the jack, the section being ta en through the connection between the actuating handle and the pivoted actuating sector: and

Figure 8 is a view taken on the line 8-8 of Figure 3.

Referring now to the drawings. the jack coma prises a chassis which, as shown in detail in Figure 2, includes a long casting or body having a relatively narrow portion 2 provided with a transversely dis osed trough portion 4 and in-- tegral, forwardly extending, spaced,

parallel arms

6 and 8 braced by a transverse wall [6. The two

arms

6 and 8 are provided with registering. bores l2 and [4 to receive a front axle IS on the extreme ends of which are mounted the rolls or wheels I3 and 20. The body 2 extends rear- Wardly in the opposite direction to provide wider spaced

parallel side walls

22 and 24 braced by a transverse wall 26. Walls -22 and 24 have registering bores 28 and 3B. In addition the

walls

22 and 24. are formed with an integral upper transverse wall 32 adjacent its rear end. The

c9 top of wall 32 is provided with the spaced notches 34 and. 36 in which depending portions are received when the lifting arm is in lowered position. In addition,

walls

22 and 24 are provided with oppositely and outwardly extending

wings

38 and 40 and with a lower transverse interconnecting web or wall I42 which latter forms one of the supports for the hydraulic unit as hereinafter described.

As seen in Figure 7, the undersurfaces of the

wings

38 and 40 are each provided with borings for the reception of rotatable bearings 48 and 50, each bearing in turn being formed with an annular groove to receive the end of a screw to hold the bearings in place while permitting rotation thereof. Each bearing carries a forked

head

52 and 54. Each such head carries a caster or wheel 53 and 58. Ball bearings 60 ensure rotation of the bearings in the wings. In addition, the

arms

22 and 24 are provided with spaced

holes

62 and 64, and 36 and 68.

The load carrying lever is shown in perspective in Figure 1 as comprising an elongated body having spaced side plates and a fiat top 14. The front of this lever is provided with spaced, forwardly projecting arms 16 and 13 each bored as at 80 and 02, and the rear end is formed with spaced pairs of rearwardly projecting

arms

84 and 86, and 88 and 90. The outermost pair 04 and 86 are formed with registering bores 92 and 94 which also register with the

bores

36 and 98 on the inner pair, and the undersides of the inner pair are notched as at I and I02. The outer ends of the inner pair of arms 88 and 90 are slightly inwardly ofiset, as seen in Figure 2.

The

outer bores

80 and 82 of the

arms

16 and 18 of the load carrying lever receive a in I04 and a pair of links I03 and I38. A load carrying saddle H3 is mounted by means of the pin I04. This saddle has an upper surface II2 centrally bored to receive the preferably circular load holder I I4 which has a central circular depending boss II 8 to engage in the bore of the surface H2. The upper surface of the load holder I I4 is suitably configured as at I I8 to hold the load.

The links I 05 and I08 are bored to receive pivotal pins I20 in turn pivotally connecting with elongated links I22 and I24. The other ends of these links pivot as at I20 and I23, see Figure 4, to the

bores

66 and 68 respectively of the

chassis sides

22 and 24, see Figure 2. This link I22 with its pivotal connections cooperates with the raising and lowering of the load raising lever 14 to maintain the load support II8 horizontal.

The underside of the load raising lever 14 carries the roller I 30 rotatably mounted thereon and in position to be contacted by the outer end of the ram of the hydraulic unit. The bearings for the roller are mounted in the slots I 00 and I02, see Figure 5.

The hydraulic unit is best shown in Figure 5. It comprises a housing I32 provided at one end with a bore to receive a pivotal pin I 34 which passes through the two registering

bores

28 and 30 of the chassis. The pin is held by a nut and a lock washer or other suitable fastener so that the unit may be detached from the chassis and preferably may swivel or pivot about the pin I34 so that it may be held by one bolt I34. It is not necessary that the swivel or pivot action be present. This power unit castingcomprises a casting or housing I32 that is provided with suitable bores for the ram cylinder, pump cylinder, relief valve, overload relief valve, reservoir and conduits for the liquid of the hydraulic system.

The power unit casting is provided with a wall portion I36 having a shoulder I38 that lies against a machined seat I40 formed on an integral wall I42 of the chassis. Thus the machined seat I40 and the pivotal pin I34 passing through the opposed registering

bores

28 and 30 of the spaced

side members

22 and 24 of the chassis form means for pivotally supporting the power unit from the chassis. This forms a simple, flexible, quick detachable mounting for the power unit. This housing I32 is generally hollow. At its base it is provided with an annular, substantially central well I44 threaded internally to receive the ram cylinder sleeve I46. In addition there is a wall I48 of the housing spaced from the well I44 to provide a liquid reservoir I50. This wall I48 has an opening closed by a filler plug I52. The

outer portions of the annular walls I52 receivean anular cap I54 which has an annular shoulder internally threaded to screw onto threads on the outer external wall of the ram cylinder I 45. This cap I54 in turn is formed with an annular shoulder I50 and a central thread to receive packing I58 and a threaded ring I60 through which moves the ram I 82. Cap I54 also has an annular projection I84 that seats against the outer face of the casting wall I52 so that the entire mounting of the ram cylinder on the housing may be drawn tight by the threads interengaging.

The well portion I44 of the casting is formed with a plurality of ports and liquid passages. There is a relatively large bore I66 formed transversely in the bottom portion of the wall I44 which has its outer end opening onto the reservoir I50 and has its central portion bored as at I68 to cause the interior of the bore I36 to connect with the interior I 10 of the well I44. A ball valve I12 and a plunger I14 are located in this bore I56. The plunger I14 has a reduced extension I16 around which fits a coiled spring I 18. The opposite end of this spring surrounds a centralized projection I on a threaded plug I82 screwed into a bore I84 formed in wall I 48 and registering with bore I66. An adjustable nut I86 permits adjustment of the tension of the spring to seat valve I12 to close port I68. This spring may thus be set to yield at a predetermined pressure within the ram cylinder and thus permit the liquid to return to the reservoir.

The ram I62 is uniquely constructed. Centrally it is provided with an elongated central bore I 89 which extends substantially to, but short of, the outer end of the ram as at I88. A short portion of this end of the bore is internally threaded to receive a screw plug I90, the inner end of which is perforated to receive one end of a coiled spring I92. The spring I92 lies longitudinally within the bore I89 and the lower end of the spring is anchored to the inner wall of the well as at I94 so that the spring constantly tends to return the ram within the cylinder. In addition the inner end of the ram is shouldered as at I96 to receive a ring I98 and a flexible gasket 200. This latter is clamped in position by a ring disk 202 and threaded retainers 204 that screw onto a threaded tubular extension 205 of the cylinder I62.

In addition, the casting wall I32 is drilled as at 206 to provide a relatively long liquid conduit, the outer end of which opens onto the outer wall of the casting and is closed by a screw plug 208. Radiating in spaced relation from this longer conduit 206 are two branch conduits 2I0 and 2I2. Branch conduit 2I0 Joins the main conduit 206 at a point relatively close to the well I'll) whereas branch conduit 2l2 joins conduit 203 relatively close to the end plug. 208; Conduit 2E0 terminates in a Valve seat 214 which is the relief valve seat; This valve seat is controlled by the ball valve 2K5. When this ball. is off its seat the conduit 2%! communicates with thereservoir i511. A rod 2E3, the same being an extension of a rod 220, controls the position of the ball 2H5 on the valve seat 214. To accomplish this the inner end of the rod portion 228 is threaded as at 222 to engage threads 223 in the intermediate portion of the housing I48. This latter portion is provided with an opening threaded as at 224 to receive a packing and a threaded plug 226., which plug and packing are perforated to receive the extension rod 220. The turning of this extension rod 220 will cause the threaded. portion thereof, 222 to move relatively to the threads 223 to advance or retreat the rod 218 and hence control the position of the ball relative to the seat 2 [4. The means for rotating the rod 220 will be hereinafter disclosed.

The conduit 2l2 terminates in a conical seat 226 which also connects with the reservoir I50. The wall I48 of the housing is provided with an additional threaded bore 23!], the central axis of which bore is in registration with the central axis of the conduit 212. This bore receives an elongated sleeve 232 threaded externally to engage the threads 23!). Sleeve 232 is provided with an intermediate hexagonal portion 234 and an outer threaded portion 236 over which threads an apertured cap 238 through Which the piston 24!) is adapted to reciprocate. The piston 240 carries on its inner end a suitabl packing 242 rigidly fastened thereto in the manner well known in the art. The outer end of the piston has a threaded hollow bore 244 to receive a threaded stud 246 the outer end of which is provided with a yoke 228 engaging over :a pin 250 which pin is mounted upon a sector-likeportion shown in perspective in Figure 6 and which will be hereinafter described. Mounted in the outer end of the high pressure pump cylinder 232 is a metallic valve cage 252 provided with internal conduits, there being a conduit 254 controlled by a ball valve 256 which in turn opens into a countersunk portion 258 which forms a passage leading to a central conduit 25!! in a conical shaped cap 252 that makes a press fit with the annular lower portion of the ball valve cage 252. This conduit 26!] in turn communicates with the conduit 2l2 hereinbefore mentioned. An additional conduit is formed in the ball valve cage 252 comprising the enlarged conduit 264 provided with a valve seat controlled by the ball valve 269. The base of this conduit 264 communicates with a lateral conduit 210 which communicates with the reservoir I50.

Means is provided for actuating the high pressure pump piston 242 and also the relief valve actuator 220 and M8 from a point remote from the chassis. In the present instance this is accomplished by means of a pivoted sector shown in perspective in Figure 6. This sector comprises two triangular spaced apart

plates

212 and 214 suitably held together by spacing pins 216 and 252. These

plates

212 and 214 have registering bores 276 to receive pins 28!) and 282, see Figure '7, about which pins the sectors are adapted to pivot; The

pins

282 and 282 in turn are threaded as at 284 and 286 into the

holes

62 and 64, see Figure 2, of the chassis. These pins in turn have

turnable heads

288 and 292 The pins also pass through bearing sleeves 292' and 224 formed in the openings 96 and 98' of the arms 88 and 90' of the lifting element 14, see Figure 2. In addition thereto the heads 288 and 296 pass through registering Openings 92 and 95, see Figure 2, in the lifting element M, to form a pivot therefor;

The mechanism for operating the relief valve actuator 220 lies between the

plates

212 and 214 as clearly shown in Figure '7. In addition, the peripheries of the discs 2'52 and 214 are provided with registering

notches

296, 298, 300 and 302 which are adapted to form a locking notch for a locking device hereinafter described. In addition there is a handle socket 304 which has a socket portion 326 and a pair of arms 308 and am which pivot on the

pins

280 and 282. This socket portion 324 is in turn provided with a lateral extension 3 l2 which is bored as at 3M to receive a locking pin 3H5 carrying the handle 3!.8 on its outer end and threadedly receiving a looking key 320. A coiled spring 322 normally maintains the locking key in outwardly pressed position to engage the socket and the socket and locking key 320 are removed by pulling outwardly and thence laterally shifting the socket to the next notch and then releasing the handle. This changes the relation between the socket 306 and the

plates

212 and 214.

The socket 326 is provided with an elongated tubular sleeve 322 within the lower endof. which is force fitted a shorter sleeve 322' having a. central hollow portion 324, and likewise having a transverse recess to receive a locking pin 325. This locking pin is adapted to engage in the cavity between the bifurcations 328 on an elongated pin 322 which is rigidly connected to one unit of a universal 338 which in turn is universally pivoted to the other unit 332 of the universal and which portion is fixed to the rod 228 of the actuator. The pin 326 freely disengages from the notch in the rod 328 when the handle is removed from its socket 30%. Means is provided for locking the extension sleeve 32a .to the handle socket 396. As shown in Fig. 7, this comprises an annular groove 336 formed between the end of the sleeve 320 and a shoulder 338 on the sleeve 322. This notch is engaged by the inner end of a pin 34c which pin is formed in a bore in the handle socket 325 and is normally spring pressed inwardly by means of a collar on the pin 35%). The pin 34! is provided with a head 344 which when pulled outwardly against the tension of the spring 322 withdraws the locking stud 324 from the notch see so that the handle extension 322 may be removed from the socket 325.

The outer end of the handle extension 32% is provided with the outwardly extending handles 34% for oscillating the handle and in addition the outer end of the handle is provided with a turnable serrated extension 348 to permit the turning of the extension 322. When the handle is oscillated, the sector-

like plates

212 and 274 will oscillate about their central pivots and by means of the pin 25% carried by these plates the high pressure pump piston 24%] is reciprocated in its cylinder to transfer the hydraulic fluid from the high pressure pump piston into the ram well I70. In accomplishing this the liquid is forced past the ball valve 256, the passageway 258, and thence into the central opening 2%, thence into the bore 2l2 which connects with the passageway 22% which in turn connects to the area il'll, in one direction of the movement of the piston, while in the other direction the liquid is sucked from the reservoir I50 past the ball valve 264 into the high pressure pump piston.

By turning the handle 320 by means of the pin 326 and the slot 328 on the extension rod 329 and the

universals

332 and 334, the rod 220 is likewise turned and by engagement of the threads 222 in their threaded opening 224 the rod actuator 2 I 8 is likewise turned to either move the ball 2H5 onto the relief valve seat or to release the same. If released, the liquid from the high pressure ram cylinder will then pass through the valve seat 2M back into the reservoir. When the ball is on its seat the liquid is held in the ram cylinder.

Obviously the invention is not limited to the specific details of construction disclosed herein but is capable of other modifications and changes which do not depart from the spirit and scope of the appended claims.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent is:

1. In a hydraulic jack, the combination of a relatively low elongated chassis having opposed spaced side frames having registering openings and means carried by and disposed across said side frame members and located in spaced relation from and rearwardly of said registering openings in the chassis and forming a transversely disposed seat for said power unit and a spaced seat, a hydraulic unit having a bore for a pivotal pin, a pivot pin passing through the registering openings of the side frames of the chassis and the hydraulic unit for pivotally mounting the hydraulic unit with respect to the spaced seat of the chassis, said unit having a corresponding seat adapted to rest on said seat, said unit including a. ram cylinder and ram and a high pressure pump cylinder piston and a relief valve actuator, said ram cylinder and ram and high pressure pump cylinder and relief valve actuator being inclined rearwardly and with respect to the longitudinal axis of the chassis, an oscillatable actuator oscillatably mounted on the extreme rear upper portion of said chassis and having a detachable connection with the high pressure pump piston for reciprocating the latter, a handle socket for actuating said actuator, said handle socket having a member therein turnable with respect to the socket and connected to the relief valve actuator for operating said valve.

2. A hydraulic unit for a jack comprising a relatively low elongated chassis provided with a hollow interior and formed with parallel side walls and a bottom seat, the side walls spaced from said seat being provided with registering apertures, said hydraulic unit comprising a housing provided at one portion with a transverse bore, a pin passing through said transverse bore and through the bores of the sides of said chassis for pivotally mounting the housing in said chassis, said housing having a cooperative seat for resting against the seat of the chassis whereby said housing is detachably mounted to said chassis, said housing including a ram cylinder and ram and a manually actuated hydraulic piston and cylinder for operating the rain, and an elongated lever overlying the top of said chassis and overlying the top of said hydraulic unit, one end of said lever carrying a load lifting saddle and the other end of said lever having pivotal openings, said chassis having additional registering openings, and a pin passing through said additional registering openings on said lever, said lever having an intermediate anti-friction member adapted in collapsed position to overlie the free end of the ram of said hydraulic unit when the lever is in collapsed position.

3. In a hydraulic jack, the combination comprising a chassis, a housing mounted thereon, said housing including a reservoir and providing a ram cylinder well, a ram cylinder mounted in the well, a ram in the ram cylinder, a high pressure pump cylinder disposed at an angle to the longitudinal axis of the ram cylinder, a piston in said cylinder, a lateral conduit formed in the housing and interconnecting the ram cylinder and high pressure pump cylinder, said ram cylinder and high pressure pump cylinder being disposed in substantially V-shaped formation and inclined upwardly to the longitudinal horizontal axis of the chassis, the passage interconnecting the ram cylinder and pump cylinder including a branch passage disposed intermediate the longitudinal axis of the ram cylinder and high pres-- sure pump cylinder, said latter passage including a relief valve seat, a valve on said seat, and a longitudinal rod-like actuator extending from said valve and projecting externally of the housing for controlling said valve, said actuator being disposed intermediate the longitudinal axes of the ram cylinder and pump cylinder, said housing and ram well having registering openings formed therein disposed normal to the longitudinal axis of the ram cylinder and interconnecting the reservoir and the well of the ram cylinder, said last mentioned conduit including a valve seat, a valve on said seat and a control member for said valve including a coiled spring, and adjusting mechanism mounted in the housing opposite said last named seat and operable from the exterior of said housing for controlling the adjustment of said spring.

4. In a, hydraulic jack, the combination comprising a relatively low elongated chassis having registering apertures at one end forming pivotal axes, pivotal pins disposed in said apertures, an elongated lifting lever carrying a load carrying saddle at one end and pairs of apertured arms at the opposite end, said arms registering with the pivotal axes of the chassis and pivoting about said pivotal pins, a hydraulic unit mounted in said chassis and including a ram and ram cylinder and a high pressure pump and pump cylinder disposed in substantial V-shaped formation with their axes inclined upwardly with respect to the horizontal longitudinal axes of the chassis, said hydraulic unit including a relief valve and a relief valve actuator disposed in the V-shaped space between the ram cylinder and the pump cylinder, an actuator for the high pressure pump piston including an oscillatable sector disposed with its pivotal axis provided with openings pivotally mounted on the pivotal pins of said chassis for oscillation thereabout, said oscillatable actuator having a connection with the high pressure pump piston and a handle adjustably connected to said actuator for oscillating the same, said handle including a relatively turnable extension, and a universal connection operatively connected to said extension and to the relief valve actuator, including a universal joint, said universal joint having its major axis registering with the axis of the pivotal pins.

5. A hydraulic unit for a jack comprising a relatively low elongated chassis provided with a hollow interior and formed with parallel side Walls or frames and a transverse bottom seat, the side walls at spaced points from said seat being provided with registering apertures, said hydraulic unit comprising a housing provided at its forward portion with a transverse bore, a pin passing through said transverse bore and through the bores of the side walls of said chassis for pivotally mounting the housing in said chassis, said housing having a cooperative seat for resting against the seat of the chassis whereby said housing is detachably mounted to said chassis, said housing including a ram cylinder and ram and a manually actuated hydraulic pump piston and cylinder for operating the ram, said cylinder ram and pump piston and cylinder being disposed in inclined relation relative to a horizontal longitudinal axis of the chassis and disposed facing the rear of the chassis, and an elongated load lifting lever overlying the top of said chassis and overlying the top of said hydraulic unit, the forward end of said lever carrying a load lifting saddle and the rear end of said lever having pivotal openings, said chassis having additional registering openings, and a pivot pin passing through said registering openings on said chassis and on said lever, said lever carrying on its underside, spaced from but near its rear end, an intermediate antifriction member adapted in collapsed position to overlie the free end of the ram of said hydraulic unit when the lever is in collapsed position.

6'. In a hydraulic jack, the combination comprising a relatively low, elongated chassis, a hydraulic unit mounted thereon including a ram cylinder and ram and a high pressure pump 'cylinder and piston disposed in substantially V- shaped relation with their longitudinal axes inclined upwardly with respect to the longitudinal horizontal axis of the chassis, a pressure relief valve disposed between the ram cylinder and high pressure pump cylinder, and an elongated rigid actuator threadedly passing through a portion of the housing of the hydraulic unit between the ram cylinder and the pum cylinder for actuating the pressure relief valve, said actuator extending externally of the housing, a load lifting lever pivotally mounted at the rear of the chassis on an axis passing through the central axis of the elongated pressure relief actuator, a pump oscillating handle pivotally connected to the chassis at said pivotal connection of said load lifting lever, said handle having a portion turnable with respect to the handle and an extension from said turnable portion having a universal connection with the outer end of the pressure relief elongated actuator, said universal connection pivoting about the pivotal connection of said load lifting lever and said pump actuator.

7. A hydraulic jack comprising a chassis, a hydraulic unit having a power driven piston slidably mounted therein, said power unit being pivotally mounted on said chassis, a seat formed on said chassis and spaced from said pivotal connection to receive the rotatable end of said power unit, means pivotal y mounted. on said chassis for operating said power piston, a load lifting lever pivotally connected to said chassis, and an anti-fricmenlher interposed between the outer end of said power piston and said lever, the pivotal connection between said lever and said chassis being disposed rcarwardly of said anti-friction member in all positions of said lever, said seat being adapted to support said hydraulic power 10 unit when said power piston is imparting an upward thrust to said load lifting member.

8. A hydraulic jack comprising a chassis, a hydraulic unit having a power driven piston slidably mounted therein, said hydraulic unit being pivotally mounted on said chassis, a seat formed on said chassis and spaced from said pivotal connection to receive said hydraulic unit, means pivotally mounted on said chassis for operating said power piston, a rotatably actuated pressure relief valve positioned in said hydraulic unit, an elongated actuator for said valve including a universal joint and having a portion disposed concentrically within said piston operating means, a load lifting lever pivotally connected to said chassis, and an anti-friction member interposed between the outer end of said power piston and said lever, the pivotal connection between said lever and said chassis being disposed rearwardly of said anti-friction member in all positions of said lever, said seat being adapted to support said hydraulic power unit when said power piston is imparting an upward thrust to said load lifting member.

9. A power hydraulic unit for a hydraulic jack comprising a housing roviding a reservoir and a ram cylinder well, a ram cylinder mounted in said well, a ram in said ram cylinder, a high pressure pump cylinder mounted in said housing, a piston in said pump cylinder, a lateral conduit formed in the housing and interconnecting said ram cylinder and pump cylinder, said ram cylinder and pump cylinder being disposed in angular relation and said pump cylinder being inclined to the longitudinal horizontal axis of said housing when the housing is mounted in a jack, the passage interconnectin said ram cylinder and pump cylinder including a branch passage disposed intermediate the longitudinal axis of said ram cylinder and pump cylinder, said last mentioned passage including a relief valve seat, a valve on said seat, a longitudinal rod like actuator extending from said valve and projecting externally of said housing for controlling said valve, said housing and ram well having registering openings formed therein interconnecting the reservoir and the well of said ram cylinder, said last mentioned opening in said ram well including a valve seat, a valve on said last mentioned seat, a control member for said last mentioned valve including spring means, and adjusting mechanism mounted in the housing wall opposite said last named valve seat and operable from the exterior of said housing for controlling the adjustment of said spring means.

JOSEPH J. MUELLER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,728,688 Vickers Sept. 10, 1929 1,940,823 Shinn Dec. 26, 1933 2,032,309 Rechard et al Feb. 25, 1936 2,039,895 Green May 5, 1936 2,039,896 Green May 5, 1936 2,250,551 Pfauser July 29, 1941