US3907252A

US3907252A - Lightweight service jack

Info

Publication number: US3907252A
Application number: US464923A
Authority: US
Inventors: Gilbert W Gaarder
Original assignee: Gray Manufacturing Co Inc
Current assignee: Gray Manufacturing Co Inc
Priority date: 1974-04-29
Filing date: 1974-04-29
Publication date: 1975-09-23
Anticipated expiration: 1992-09-23

Abstract

A lightweight, efficient, portable service jack for automobiles or the like which is extremely compact by provision of a pivotally mounted, direct-acting hydraulic cylinder with separate unique pump and release mechanisms positioned adjacent the cylinder on opposite sides thereof and operatively connected thereto through oppositely extending, axially bored mounting trunnions which define the transverse pivot axis of the cylinder and are secured thereto for rotation therewith as the cylinder pivots during raising and lowering of the jack. In preferred forms the simplified jack construction hereof utilizes a tension link lift arm design wherein the extensible, pressure-responsive cylinder ram is connected to the outermost end of the lift arm of the jack in order to absorb substantially all of the compressive and bending forces normally experienced thereby; this allows reduction of the number, weight and cost of structural elements of the jack without a concomitant decrease in the lifting capacity thereof. The side-mounted pump mechanism of the jack is preferably fixedly secured to the jack frame and operatively connected to the adjacent pivotal, hydraulic cylinder through the axial bore of one of the pivotal mounting trunnions, while the release mechanism includes an elongated, axially movable, freely rotatable release rod carried within the remaining trunnion bore and axially displaceable between positions respectively precluding and permitting return flow of hydraulic fluid from the inner, concentric pressure chamber of the cylinder to the annular, outermost fluid reservoir thereof. A release screw is provided adjacent the outermost end of the release trunnion which is manually actuatable to effect selective displacement of the release rod between the operative positions thereof as desired.

Description

United States Patent 1191 Gaarder [451 Sept. 23, 1975 1 LIGHTWEIGHT SERVICE JACK Gilbert W. Gaarder, St. Joseph, Mo.

[73] Assignee: Gray Manufacturing Company, Inc.,

' St. Joseph, Mo.

[22] Filed: Apr. 29, 1974 [21] Appl. No.: 464,923

[75] Inventor:

Primary Examiner-Al Lawrence Smith Assistant Examiner-Robert C. Watson Attorney, Agent, or FirmSchmidt, Johnson, Hovey & Williams [5 7] ABSTRACT A lightweight, efficient, portable service jack for automobiles or the like which is extremely compact by provision of a pivotally mounted, direct-actinghydraulic cylinder with separate unique pump and. release mechanisms positioned adjacent the cylinder on opposite sides thereof and operatively connected thereto through oppositely extending, axially bored mounting trunnions which define the transverse pivot axis of the cylinder and are secured thereto for rotation therewith as the cylinder pivots during raising and lowering of the jack. ln preferred forms the simplified jack construction hereof utilizes a tension link lift arm design wherein the extensible, pressure-responsive cylinder ram is connected to the outermost end of the lift arm of the jack in order to absorb substantially all of the compressive and bending forces normally experienced thereby; this allows reduction of the number, weight and cost of structural elements of the jack without a concomitant decrease in the lifting capacity thereof. The side-mounted pump mechanism of the jack is preferably fixedly secured to the jack frame and operatively connected to the adjacent pivotal. hydraulic cylinder through the axial bore of one of the pivotal mounting trunnions, while the release mechanism includes an elongated, axially movable, freely rotatable release rod carried within the remaining trunnion bore and axially displaceable between positions respectively precluding and permitting return flow of hydraulic fluid from the inner, concentric pressure chamber of the cylinder to the annular, outermost fluid reservoir thereof. A release screw is provided adjacent the outermost end of the release trunnion which is manually actuatable to effect selective displacement of the release rod between the operative positions thereof as desired.

32 Claims, 10 Drawing Figures US Patent Sept. 23,1975 Sheet 2 of3 3,907,252

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US Pawn-t Sept 23,1975 Sheet 3 of3 3,907,252

.mw am QN 1W & x g L :2 3m Em SN mm 9% QM QM w: 8 Rm 5 WW @m M \nmvms Km NAN M m \.L RN mmw Ew R 5 n fi m: w I a g Q: m? mi mm a Ja Q mm W w kw g P 3 s k mm Q m why kw E @S a n J 7 3 5 Q E Z m fl L W Q m/w 7/ W7 QR 1 WV @N t U @QN m /N wowwaw Qw smw 5 .3 mu 3 I Na mg Qw W M 5 Q: a m n9 Qmw v9 LIGHTWEIGHT SERVICE JACK This invention relates to a lightweight, efficient, com: pact, portable service jack which utilizes'a pivotally mounted, direct-acting hydraulic cylinder with unique: pump and release mechanisms conveniently positioned adjacent the cylinder on. opposite sides thereof. More,

particularly, it is concernedwith a jack of the described class wherein the side-mounted pump and release mechanisms are operatively connected through-oppo-.

sitely extending, axially bored mounting trunnionsconnected to the hydraulic cylinder to define the transverse pivot axis thereof and rotate in unison therewith.

In particularly preferred forms, the outermost end of the extensible, pressure-responsive ram of the cylinder is connected to the outermostend of the lift arm, to thereby absorb substantiallyall compressive and bending forces normally experienced thereby and transform the lift arm of the jack into a tension link member.

Many garage and service station owners have expressed the need for a rugged yet lightweight and cornpact service jack. In this connection it is important that such a jack be compact and sufficiently light in weight to permit easy handling thereof by a single mechanic or operator. As can be appreciated, labor costs preclude sending two men on a road call simply because the road jack is too cumbersome to be easily handled by a single mechanic. 1 The portable jacks heretofore available have oftentimes been on the order of 70 or 80 pounds in weight and sufficiently cumbersome to make it difficult for one man to handle the same. Therefore, when garages have been called upon to make road service calls, they have either sent two men to the disabled auto or have towed the car back to the garage usinga tow truck with only a single driver. Obviously, both of these alterna-' tives are costly to the customers of the garage since many services, for example the changing of a flat tire or the like, could easily be performed atthe roadside location by a single mechaniclt will also be readily appreciated that a portable service jack must ofnecessity be rugged and able to withstand the normal shocks and abuse inherent in roadside servicing, without, of course, detracting from the easy utility thereof. However, by virtue of the lack of such an-efficient, rugged, lightweight jack which can be handled and carried by a single operator, roadside servicing has heretofore been somewhat difficult. I

It is known that the number, weight and cost of the structural components of a portable service'jack can be reduced by provision of a pivotally mounted, direct acting hydraulic cylinder having the extensible ram thereof connected to the jack lift structure such that the cylinder pivots during raising and lowering of the jack. The advantages of this type of lift arrangement are maximized by utilization of what canbe termed a tension link lift arm design. In this design a pivotally mounted direct-acting hydraulic cylinder is utilized with articulates through a relatively large arc'of rotation during raising and lowering of the jack, and which has the extensible, pressure-responsive ram thereof connected at its outermost end to the corresponding outermost end of the lift arm of the jack rather than to a point intermediate along the length thereof. In this fashion, substantially all of the compressive and bending loads normally experienced by the lift arm are absorbed by the extensible ram so that in effect, thelift arm becomes merely a tension link rather than aloadbearing member. Since the hydraulic ram absorbs substructures or the like to stabilize the frame and lift arm,;

as is common with conventional jacks.

A persistent problem encountered in the design of tension link lift arm jack mechanisms stems from the,

need of providing convenientpump and release mechanisms therefor. On conventional jacks having lift arms which experience bending and compressive loads, the. hydraulic cylinder itself is essentially fixed in its mounting-to the jack frame. Therefore, it is convenient in such jacks to incorporate the pump and release controls (the two elements requiring manual attention) on the hydraulic cylinder base or block. In contradistinc-- tion thereto, with jacks of the tension link lift arm design, the pump and release control cannot be attached, directly to the cylinder block in a practical manner.-

This results from the fact that at certain intervals during articulation of the hydraulic cylinder, the manually operable controls, if attached directy thereto, would be I at an inconvenient location or completely inaccessible to the operatonlt is readily apparent that this is an extremely objectionable result because of the necessity of providing conveniently situated pump and release mechanisms which are accessible to the operatorgduring all phases of the jack operation..-

One response to the problems alluded to-a bov eis dis; closed in U.S., Pat. No. 2,605,999. In this instance, a

jack utilizing the tension link lift arm design is disclosed which'employs a hydraulic pump and reservoir mechanism centrally positioned rearwardlyof the pivotally mounted hydraulic cylinder and communicating therewith through a complexseries of hydraulic fluid ducts and the like which requires a. plurality of-costly high pressure rotary seals. Furthermore, by virtue of the rel.- ative arrangement between the hydraulic cylinder and pump mechanism therefor, the size and weight of the jack is materially increased and the pumping forces developed during raising of the jack can cause frame deflections and produce radial loads on the transverse, rotatable cylinder mounting trunnion utilized, all of which are undesirable factors,

Because of the problems alludedto above, it is difficult to design tension link lift arm jacks having rear, mounted pump mechanisms as exemplified in US. Pat. No. 2,605,999 which take full advantage of the weight reduction and compactness potentially available through the use of the tension link lift arm concept.

Hence, there is a need in the art for a rugged, yet lightweight, compact and efficient portable service jack for automobiles or the like which includes a pivotally mounted, direct-acting cylinder and preferably-a tension link lift arm design, and which includes convenient pump and release mechanisms asan adjunct thereof whichare completely accessible to the operator during all phases of jack operation, and which do not detract from the size and weight savings inherent in the jack design. v i

It istherefore the most important object of the present invention to provide a lightweight, compact, efficient portable service jack which can be easily lifted,

carried and handled by a single person and is of the type utilizing a pivotally mounted, direct-acting hydraulic cylinder having as an adjunct thereof convenient pumping and release mechanisms which are accessible to the operator during all phases ofjack operation.

Another object of the invention is to provide a jack of the class described wherein the pivotally mounted hydraulic cylinder thereof has pump and release mechanisms positioned adjacent the cylinder on opposite sides thereof and operatively connected thereto through oppositely extending, axially bored mounting trunnions which define the transverse pivot axis of the cylinder and are secured thereto for rotation therewith as the cylinder pivots during raising and lowering of the jack. In this fashion, the pump and release mechanisms, being located in adjacent, side-by-side disposition with respect to the hydraulic cylinder, remain unobstructed and easily accessible during use of the jack, even when the latter is raised to the maximum extent thereof.

Another particularly important object of the invention is to provide a jack with a pivotally mounted, direct-acting hydraulic cylinder and separate, oppositely positioned side-by-side pump and release mechanisms, wherein the extensible, pressure-responsive cylinder ram is connected to the outermost end of the lift arm 7 of the jack to thereby absorb substantially all compressive and bending forces normally experienced by the lift arm which in effect transforms the latter into simply a tension link. As a consequence thereof, the number, weight and cost of the structural components of the jack is considerably reduced, which results in significant size and weight savings and provides a compact service jack which nevertheless retains a lifting capacity sufficient for all uses for which the jack is intended.

A still further object of the present invention is to provide a jack wherein a pair of elongated, oppositely directed, axially bored mounting trunnions are threadably connected to the base section of the hydraulic cylinder and rotatably mounted within the jack frame structure for rotation with respect to the latter. As a corollary to the foregoing, the pump mechanism is preferably fixedly secured to the jack frame and operatively connected to a rotatable mounting trunnion through a rotary seal, with the pump being operable to selectively draw hydraulic fluid from a reservoir thereof and return the same through the communicating mounting trunnion bore to the pressure chamber of the hydraulic cylinder to thereby effect raising of the jack.

Yet another aim of the present invention is to provide side-mounted release mechanism for the described jack which comprises an elongated, axially movable, freely rotatable release rod carried within the remaining axial trunnion bore and movable therein between a first position permitting return flow of hydraulic fluid from the cylinder pressure chamber to the fluid reservoir, and to a second release position permitting such return flow. In this connection, a manually actuatable release screw is provided adjacent the outermost end of the release mounting trunnion which is operable to engage the proximal outermost end of the release rod and move the same as desired between the second and first positions thereof. The release screw is mounted within support structure therefor and is held against rotation with the mounting trunnion; the release screw advantageously includes a conical section along the length thereof in engagement with the outermost end of the release rod such that as the release screw is threadably advanced, the increasing diameter of the conical section engages the release rod and progressively displaces the latter inwardly until the flow preventing disposition of the rod is reached. Likewise, upon retraction of the release screw, the release rod is displaced outwardly under'the influence of hydraulic pressure to permit fluid flow between the pressure chamber of the hydraulic cylinder and the fluid reservoir associated therewith.

Another object of the instant invention is to provide a portable service jack incorporating the tension link lift arm design wherein the pump and release mechanisms thereof are positioned on opposite sides of the pivotal hydraulic cylinder, and wherein the release mechanism is secured to the hydraulic cylinder but unconnected to the proximal jack frame structure, whereby the cylinder and release mechanism can accommodate slight lateral movements caused by loads imposed thereon during the pumping of the jack, without deleteriously affecting the release function thereof.

A still further object of the present invention is to provide a pivotally mounted, direct-acting hydraulic cylinder which comprises an elongated, cylindrical hollow member including an annular, outermost hydraulic fluid reservoir holding a supply of hydraulic fluid, and an inner concentric pressure chamber housing a pressure-responsive, axially movable pressure piston which has an elongated rod or ram journaled thereon and extending from the pressure chamber.

Yet another object of the present invention is to provide a hydraulic cylinder having a block section at the base thereof for threadably receiving the opposed, oppositely extending, axially bored mounting trunnions, the block'having therein a series of hydraulic fluid passageways communicating the side-mounted pump mechanism with the annular fluid reservoir and .concentric pressure chamber respectively, the passageways being configured and arranged to permit fluid to be drawn from the reservoir through the pump trunnion bore and into the pump block, and returned to the pressure chamber under pressure through the same trunnion bore to effect raising of the jack. Similarly, hydraulic fluid passageways are provided for communicating the high pressure chamber of the cylinder with the axial bore of the release trunnion, and for communicating the latter bore with the annular hydraulic fluid reservoir. In this manner, the release rod can be moved outwardly to permit fluid flow therepast from the pressure chamber and ultimately to the hydraulic fluid reservoir to effect lowering of the jack.

In the drawings:

FIG. 1 is a side elevational view of a jack in accordance with the present invention in its most extended position and showing the external side-mounted pump mechanism;

FIG. 2 is an end elevational view of the jack shown in FIG. 1, viewing from the rearward end thereof;

FIG. 3 is a fragmentary, end elevational view taken along line 3-3 of FIG. 1 and depicting in detail the connection of the lift pad, lift arm, and extensible cylinder ram;

FIG. 4 is a side elevational view similar to that shown in FIG. 1 but with the jack in its lowered position and showing the external side-mounted release mechanism thereof;

FIG. 5 is a fragmentary view in partial'vertical section showing in detail the pivotally mounted, direct-acting, hydraulic cylinder for use in the jack of the present invention;

FIG. 6 is a sectional view taken along line 66 of FIG. 5 showing the hydraulic cylinder withopposed, oppositely extending mounting trunnions mounted on opposite sides of the base thereof, with the piston and rod assembly removed;

FIG. 7 is a sectional view taken along line 77 of FIG. 1 and depicting in detail the side-mounted pump and release mechanisms of the present invention, along with the hydraulic fluid passageways provided in the cylinder block;

FIG. 8 is a fragmentary view in section taken along line 8-8 of FIG. 7 and illustrating in detail the hydraulic fluid passageways provided in the cylinder block for pumping the jack;

FIG. 9 is a fragmentary sectional view taken along irregular line 9-9 of FIG. 7 and further illustrating the hydraulic passageways associated with the sidemounted release mechanism; and

FIG. 10 is a fragmentary sectional view illustrating in detail the fluid passageway structure associated with the manually adjustable bypass relief mechanism of the jack.

Turning now to the drawings, there is shown in FIGS. 1, 2 and 4 a jack in accordance with the present invention. Jack 20 includes a frame structure having a pair of spaced

side plates

22 and 24 with two pairs of

wheels

26 and 28 positioned at the forward and rearward ends of the

plates

22 and 24 respectively. Spaced wheels 28 are positioned exteriorly of the

side plates

22 and 24 at the rearward end thereof and are journaled on transverse axle 30 which extends through apertures provided therefor in the

side plates

22 and 24 Wheel 28 adjacent side plate 22 is affixed to axle 30 by means of spring clip 32, while the correspondingwheel 28 adjacent plate 24 is attached thereto by means of a removable threaded nut 34. Similarly, spaced wheels 26 at the forwardmost ends of the spaced

side plates

22 and 24 are journaled onto transverse axle 36 Wheel 26 adjacent side plate 22 is attached to axle 36 by provision of spring clip 38, while wheel 26 adjacent side plate 24 is removably attached to axle 36 by means of threaded nut 40.

Interconnection between the spaced

side plates

22 and 24 is completed by provision of transverse pin 42 extending between the side plates at a point above wheels 28. Pin 42 has a collar 44 forming a part of lift arm 46 pivotally mounted thereon between

side plates

22 and 24, and pump handle bracket 48 is pivotally secured over pin 42 adjacent the exterior face of side plate 22 for purposes which will become clear. A pair of threaded mounting

nuts

50 and 52 are attached to the respective ends of pin 42 in order to secure

side plates

22 and 24, collar 44 and pump handle bracket 48 thereon in the manner depicted.

Elongated, plate-like arm 46 has integral collar 44 at the base thereof and is pivotally secured about pin 42 between

side plates

22 and 24. At the outermost end thereof, lift arm 46 is pivotally secured to lift pad 54. The latter includes a generally planar object-engaging plate 56 having upturned ends as at 58, and integral, depending sidewalls 60 and 62. An upper transverse wrist pin 64 extends between the spaced

sidewalls

60 and 62 and is retained therein by means of external spring clips 66.

Lift arm 46 having spaced, downturned sidewalls 72 also includes a pair of spaced reinforcing

extensions

74 and 76 which are welded as at 78 to the inside of sidewalls 72 and define the forward end of the lift arm.

Extensions

74 and 76 are dimensioned to extend into the space between depending sidewalls 60 and 62 of lift pad 54, and are apertured at the uppermost ends thereof in order to permit pivotal mounting of lift arm 46 on upper wrist pin 64, as shown in FIGS. 1-3.

The outermost end of extensible, pressure responsive cylinder piston rod or ram 80 is likewise pivotally mounted on upper wrist pin 64. In this regard, a mounting block 82 is rotatably journaled on wrist pin 64 with the outermost end of ram 80 fixedly but removably keyed therein by means of locking pin 84. In this regard, pin 84 is cooperatively received within an annular groove (not shown) about the uppermost end of ram 80,.and the bore provided therefor in block 82. This produces a wedging action on ram 80 for releasably holding the same within block 82. It will be appreciated from the foregoing that during raising and lowering of jack 20, lift arm 46 and ram 80 will articulate in unison with respect to lift pad 54 about the axis defined by transverse wrist pin 64.

A pair of spaced,

identical tie rods

86 and 88 are pivotally secured to lower wrist pin 68 adjacent the exterior faces of the

respective sidewalls

60 and 62 of lift pad 54.

Tie rods

86 and 88 are pivotally secured at their lowermost ends to

side plates

22 and 24 respectively by means of short, inwardly extending mounting gudgeons 90 on the interior faces of

side plates

22 and 24. In the conventional fashion, the

tie rods

86 and 88 are secured to the respective pivot axes thereof by means of spring clips 92 and 70. The

tie rods

86 and 88 are utilized in the normal manner to stabilize lift pad 54 and prevent untoward pivotal movement thereof.

The lift mechanism ofjack 20- is completed by provision of an elongated helical spring 94 which is connected at the opposed. ends thereof to wrist pin 68 and to a lower mounting bracket (not shown) attached to the interior face of side plate 22. Spring 94 acts to urge lift pad 54 downwardly to the rest position thereof shown in FIG. 4 when the jack is released.

A direct-acting hydraulic cylinder 96 is pivotally mounted between

side plates

22 and 24 by a pair of elongated, oppositely extending, axially bored mounting

trunnions

98 and 100 which are connected to the lowermost hexagonal block 102- of cylinder 96 and define a transverse pivot axis for the cylinder within jack 20.

Referring specifically to FIGS. 5 and 6, the cylinder 96 will be described in greater detail. Cylinder 96 includes an elongated, outermost cylindrical sidewall 104 which is secured between-lower block 102 and upper cap section 106. A pair of circular O-

ring seals

108 and 110 are provided in corresponding recesses in block 102 and cap 106 for the purpose of providing a fluidtight seal between the same and wall 104. A concentric, cylindrical inner wall 112 of greater thickness than wall 104 is threadably mounted as at 114 within block 102, and a fluid-tight seal therebetween is maintained by provision of annular gasket 105. Similarly, cap section 106 is threadably secured to the upper end of wall 112 as depicted at 116. The annular space between

concentric walls

112 and 104 serves as a hydraulic fluid reservoir 118 for the purpose of holding a supply of hydraulic fluid. The concentric space within the confines of wall 112 on the other hand forms an elongated concentric chamber 120.

A pressure-responsive piston 122 is slidably positioned within chamber and has extensible ram 80 connected thereto for movement therewith. In this manner, a high-pressure chamber 123 is provided behind piston 122 and defined by the latter, block 102 and wall 112. A low-pressure chamber 125 is likewise provided ahead of piston 122 and defined by the latter, cap 106 and wall 112. Ram 80 includes an integral, elongated extension 124 having a threaded outermost end 126 which extends through an aperture provided therefor in piston 122. Connection to piston l'22'is completed by a washer 128 and threaded nut 130 which cooperatively secure ram 80 to piston 1'22. l-Iydraulic fluid sealing is provided by means of annular high pressure seal 132 which seats within a complemental recess therefor on the underside of piston 122, and a high-pressure O-ring static seal 134 provided about extension 124 within piston 122. 1

An access fitting 136 releasably closed by threaded screw 138 is provided in wall 104 to permit filling or replacement of reservoir 118 with hydraulic fluid. In this connection, a bored return vent 140 is provided in cap section 106 in order to communicate low-pressure chamber 125 with reservoir 118 at the adjacent upper ends thereof. This is to permit return to reservoir 118 of any seepage of hydraulic fluid contained in chamber 125 forwardly of piston 122. Finally, low-pressure O ring seal 142 is seated within an appropriate recess in cap 106 for the purpose of providing a sliding seal with reciprocal ram 80. A short section of magnet 143 is positioned against wall 104 within reservoir 118 which acts as a collector for any metallic filings or particle within the hydraulic fluid.

It will be appreciated from the foregoing description that the cylinder 96 can be assembled by first threading inner wall 112 into block 102 to assure a fluid-tight seal with gasket 105. At this point, seal 110 and magnet 143 are installed, whereupon wall 104 is positioned on block 102. Piston 122 having ram 80 connected thereto is then placed within chamber 120 and the annular reservoir 118 filled with oil, followed by positioning of

seals

108 and 142 and attachment of cap 106.

Turning now to FIG. 7, it will be seen that hexagonal block 102 is provided with a pair of opposed, inwardly directed threaded

openings

144 and 146. Elongated right-hand mounting trunnion 98 is threadably received within opening 144 and includes a high-pressure O-ring seal 148 sealed in an appropriate recess therefor adjacent the threaded portion thereof, and a radially expanded spacer segment 150 which maintains block 102 in proper spaced alignment with side plate 22. An integral concentric bearing portion 152 extends outwardly from spacer segment 150 and has a concentric extension 154 extending therefrom into pump block 156. The integral mounting trunnion 98 is axially bored as at 158 in order to communicate pump block 156 with the hydraulic fluid passageway system of cylinder block 102, to be described in detail hereinafter.

Side plate 22 is apertured as at 160 to permit bearing portion 152 and extension 154 of mounting trunnion 98 to extend therethrough. An outwardly extending, apertured mounting bushing 162 is secured within aperture 160 of side plate 22 for the purpose of rotatably A high-pressure seal 166 backed by metallic reinforcing ring 168 is provided about extension 154 of mounting trunnion 98 for the purpose of precluding leakage of highly pressurizedhydraulic fluid developed during pumpingof jack 20. It will be appreciated from the foregoing thatby. virtue of the threaded connection between block 102and mounting trunnion 98, the latter pivots in unison with cylinder 96 during raising and lowering of jack 20 while the frame assembly remains stationary. 7

Pump block 156 is fixedly secured to the outer face of side plate 22 by means of

screws

170 and 172. Block 156 also includes an elongated, stepped plunger bore 174 having the uppermost end thereof threaded as at 176 andprovided with an intermediate stepped section 178 holding high pressure annular seal 180. A block cap 182 is threadably mounted within pump block 156 at the upper end thereof and has an innermost reinforcing portion 184 for backing high-pressure seal 180. The lower portion of plunger bore 174 communicates with transverse bore 186 which, as depicted, receives the outermost extension 154 of mounting trunnion 98.

Pump block 156 also includes an axially reciprocable plunger 188 which can be manually actuated to successively 'draw hydraulic fluid from annular reservoir 118 of cylinder 96, a nd' return the same under pressure to chamber 120 to effect raising of jack 20. In this connection, pump handle bracket 48 pivotally mounted on pin 42 over removable sleeve 190 includes a rearwardly extending, tubular handle-receiving socket 192 which is configured to receive an elongated handle 194 which can be manipulated by the operator in an up-and-down fashion in order to raise jack 20. Bracket 48 also includes a pair of depending, spaced

plates

196 and 198 having transverse pin 200 connected therebetween adjacent the lower ends thereof and retained in place by means of spring clips 202 and 204. Plunger 188 is pivotally mounted at the upper end thereof to transverse pin 200 by means of mounting collar 206 which has lower inturned flange sections 208 adapted to seat within groove 210 provided in plunger 188 adjacent the uppermost end thereof.

It will be readily seen from the foregoing description that when handle 194 is grasped by the operator and pulled upwardly, pump handle bracket 48 pivots about pin 42 and through the described linkage, plunger rod 188 is drawn upwardly within plunger bore 174. Similarly, when handle 194 is pushed downwardly, plunger rod 188 is in turn driven back into plunger bore 174.

Turning now to FIGS. 7 and 8, the hydraulic fluid passageways provided in block 102 to permit raising of jack 20 will be' described. In particular, a stepped, obliquely disposed, transverse primary bore 212 is provided in block 102 which includes a series of concentric longitudinally aligned sections along the length thereof. Primary bore 212 is threaded along the portion thereof of greatest diameter as at 214 and receives therein'an access nut 216 normally plugging the end of the bore. Access nut 216 also includes a high-pressure seal to preclude leakage of hydraulic fluid therepast. A generally'frustoconical valve ball seat 218 is provided in bore 212 and spaced from threaded section 214 in order to define a valve ball seat for valve ball 220 normally seated thereagainst and urged into seating position by means of helical spring 222. Similarly, a second,

inwardly extending, generally frustoconical valve ball seat 224 is provided within bore 212 spaced from seat 218 for the purpose of seating smaller valve ball 226 thereagainst under the influence of hydraulic pressure. A low tension helical spring 228 is interposed between

valve balls

220 and 226 within bore 212 for the purpose of preventing flow of priming oil from pump block 156 to reservoir 118 when the jack is lifted and carried by rear axle 30.

An axially extending duct 230 is provided in block 102 for communicating annular hydraulic fluid reservoir 118 with the extreme constricted end of primary bore 212. Similarly, a second axial duct 232 communicates high-pressure chamber 123 with primary bore 212 at a point on the latter intermediate threaded section 214 and valve seat 218.

Referring now to FIG. 7, it will be seen that a transverse duct 234 communicates threaded bore 144 with primary bore 212 at apoint between valve ball seats 218 and 224 of the latter order to establishcommunication between primary bore 212 and axial bore 158 of mounting trunnion 98. t I I When it is desired to elevate jack 20, handle 194 is positioned within socket 192 therefor and manipulated in up-and-down strokes. On the upstroke of handle 194, plunger rod 188 is partially withdrawn from plunger bore 174 as described above, which draws hydraulic fluid from annular reservoir 118 through axial duct 230. This has theeffect of overcoming low tension spring 228 and displacing valve ball 226 leftwardly as viewed in FIG. 8 from valve seat 224, which in turn permits flow of hydraulic fluid through transverse duct 234 and ultimately through axial trunnionbore 158 and into plunger bore 174. On the downstroke of handle 194, plunger rod 188 is forced downwardly which presurizes I the increment of hydraulic fluid within plunger bore 174 and directs the pressurized fluid back through axial trunnion bore 158 and transverse duct 234.

By virtue of the fact that transverse duct 234 communicates with primary bore 212 at a point above valve ball 226 as viewed in FIG. 7, the latter is pushed downwardly by the return flow of pressurized hydraulic fluid from pump block 156 (and also by the action of spring 228), to thereby effect a fluid tight seal with valve seat 224. This sealing action has the effect of precludingdirect return flow of pressurized hydraulic fluid to annu lar reservoir 118. The pressurized hydraulic fluid re turning from pump block 156 in consequence acts on valve ball 220 to displace the same against the biased urging of spring 222 therebehind to break the seal between valve ball 220 and valve seat 218. When valve between threaded section 214 and valve seat 218; however, these ducts remain sealed during the pumping ope'ration and thus do not effect the efficiency thereof, as

ball 220 is sufficiently displaced, the pressurized hydraulic fluid flows therepast and thence into axial duct 232 which communicates with high-pressure. chamber 123 behind piston 122. In the well-known manner,.thisg nicate with primary bore 212 along the length thereof will be more fully explained below.

Release mounting trunnion. is similar in many respects to mounting trunnion'98 and includes an inwardly extending, threaded portion 240 which is threa'dably received within threaded bore 146 provided in block 102. A sealing O-ring 242 is provided adjacent the innermost end of trunnion 1110 to provide a highpressure seal between the latter and bore 146. Bore 146 also includes a stepped portion 244 spaced outwardlyfrom the innermost end thereof to define an annular space 246 about trunnion 100. The connection of trunnion 100 within block 162 is completed by provision of an O-ring 248 provided adjacent the outermost end of threaded extension 240.

An integral, radially enlarged spacer segment 250 is provided on trunnion 100 exteriorly. of block 102 for the purpose of spacing the latter from side plate 24. In this connection, trunnion 101} is rotatably fitted within the overall jack frame structure and unconnected thereto such that the trunnion can move laterally to a slight degree with cylinder 96 during raising ofjack 20. This feature is important for reasons to ,be explained hereinafter. Trunnion 100 also includes a coaxial, outwardly extending bearing portion 252 of reduced radial dimensions, and a coaxial outermostthreaded. extension 254 extending outwardly from side plate 24.

Side plate 24 is apertured as at 256 and includes a cylindrical mounting bushing 258 secured withinaperture 256. An annular bearing member 260 is' positioned within mounting bushing 250 in circumscribing rela tionship to bearing portion 252 of mounting trunnion 100 for the purpose of-rotatably mounting the latter within side plate 24.

Mounting trunnion 100 is axially bored as at 262, and at the innermost end thereof bore 262 includes a con: centric portion 264 of reduced diameter with an inwardly extending, frustoconical valve seat 267 betweenthe portion 264 and the remainder of bore 262. An axially movable, freely rotatable, segmented release element 266 is carried within trunnion bore 262 ,and includes an elongated, outwardly extending rod-like portion 268 having a beveled outermost end 270 extending from bore 262, and an O-ring seal 273 positioned inter mediate of the length thereof.

Release element 266 also includes as innermost segment 272 having a conical leading portion 274 which is adapted to seat against valve seat 267 and provide a fluid-tight seal therewith. A spacer ball 276 is interposed between

sections

268 and 272 of release element 266 for the purpose of insuring smooth reciprocation of the entire release assembly.

Mounting trunnion 100 also includes a transversely extending, oblique fluid passageway 278 which com municates trunnion bore 262 with annular space 246 about the periphery of the trunnion. Referring specifically to FIG. 9, an axial duct 281) is provided in block 102 which communicates hydraulic fluid reservoir 118 with annular space 246. In this manner, fluid passageway communication is established between fluid reservoir 118 and high-pressure chamber 123 through the inner portion of trunnion bore 262.

Manipulative mechanism for selectively displacing release rod 266 is positioned adjacent the exterior face of side plate 24 and is generally referred to by the numeral 282. Mechanism 282 includes an annular washer 284 slipped over threaded extension 254 of mounting trunnion 100 extending through aperture 256 of side plate 24, with a threadably mounted collar 286 mounted on extension 254. Collar 286 serves to releasably maintain apertured cup-like segment 288 in position about release rod 266, in conjunction with integral stud 289 extending outwardly from side plate 24 and received within recess 291 provided in the wall of cuplike segment 288. The described structure permits mounting trunnion 100 to pivot with respect to fixedly mounted cup-like segment 288, which is important by virtue of the fact that manipulative mechanism 282 would normally tend to pivot with trunnion 100. This undesirable result could cause the mechanism 282 to pivot to inaccessible locations during some phases of jack operation. However, manipulative mechanism 282 is not positively secured to side plate 24 but can move laterally to a limited degree with respect thereto, while still not pivoting with trunnion 100. This feature permits the entire release apparatus, including manipulative mechanism 282, to accommodate lateral movements of cylinder 96 caused by lateral forces developed during pumping.

Cup-like segment 288 is also adapted to locate release screw 290 in a position proximal to the beveled end 270 of elongated, rod-like segment 268 and maintain the convenient attitude of screw 290 during all phases of jack operation. In particular, release screw 290 is threaded as at 292 and can be advanced or retracted by axially turning the same. Screw 290 includes an integral frustoconical segment 294 along the length thereof which is adapted to abut the beveled end 270 of segment 268, the latter of which is freely rotatable within trunnion 100 with respect to screw 290. In order to facilitate selective movement of release screw 290, the latter is provided with a transverse thumb-latch 296 at the top thereof, and a keeper ring 298 adjacent the lower portion thereof in order to preclude complete removal of the screw from cup-like segment 288.

When it is desired to lower jack from an elevated work position, the following procedure is followed. First, release screw 290 is turned in a counterclockwise direction in order to retract the same from the flowrestricting position thereof depicted in FIG. 7. This, in turn, permits segmented release element 266 to be displaced outwardly with respect to block 102 under the influence of hydraulic fluid from high pressure chamber 123, which communicates therewith through duct 232, primary bore 212, transverse duct 236, and finally through the forward constricted end 264 of trunnion bore 262. When the conical leading portion 274 of release rod segment 272 is displaced leftwardly as viewed in FIG. 7, the flow restricting seal maintained with valve seat 267 is broken, which permits hydraulic fluid to flow past segment 272 and thence through passageway 278. In this connection, it should be noted that release element section 272 is advantageously closely dimensioned with respect to trunnion bore 262 such that a metering effect is produced during jack release which precludes the possibility that relatively large volumes of hydraulic fluid could quickly flow from pressure chamber 123; this facilitates control of the rate of jack descent by restricting return fluid flow to reservoir 118. Upon leaving fluid passageway 278, the hydraulic fluid from high-pressure chamber 123 enters annular space 246 about the periphery of mounting trunnion 100 which is in communication with axial bore 280. At this point, the hydraulic fluid is returned to reservoir 118 which permits lift pad 54 to be lowered with consequent retraction of ram and downward pivotal movement of cylinder 96.

If it is again desired to raise jack 20, release screw 290 is advanced within cup-like segment 288 in order to displace release rod 266 inwardly to the flow preventing disposition thereof as explained. At this point, the manual pumping mechanism described above can be manipulated in order to again raise the jack.

A secondary bypass pressure relief mechanism is provided in jack 20 for the purpose of delivering pressurized hydraulic fluid developed during pumping directly back to reservoir 118 during overload situations. This function could be required when lift pad 54 is elevated to its maximum extent or where the load capabilities of the jack have been met or exceeded. In these situations, continued pumping could result in a damaging overpressure within cylinder 96, and accordingly, a bypass relief function is desired. Referring specifically to FIGS. 7 and 10, a transverse hydraulic fluid duct 238 is provided between seat 218 and duct 236 and in communication with primary bore 212 adjacent valve ball seat 218. Duct 238 communicates with an elongated bore 300 which has a threaded outermost portion as at 302. An adjustable threaded screw 304 is received within threaded section 302 of bore 300 and includes an annular O-ring seal 306 provided in a recess therefor under the head of screw 304. A helical spring 308 having a central innermost valve ball support 310 is interposed within bore 300 between screw 304 and duct 238. A valve ball 312 is in engagement with ball support 310 which urges the former into sealing engagement with ball seat 314 provided at the juncture between duct 238 and bore 300. In the well-known fashion, the biasing force exerted upon valve ball 312 can be varied by adjusting screw 304 which acts through helical spring 308.

When an overload condition has been reached, back pressure within high-pressure chamber 123 created by the external load on pad 54 is sufficient to overcome spring 308 to thereby open duct 238. Thus, during continued pumping in this mode, hydraulic fluid is continuously drawn from reservoir 118 and returned thereto through duct 238, bore 300 and axial relief duct 316, with no effect upon the lift structure of the jack.

In view of the foregoing, it will be readily apparent that during raising and lowering of jack 20, the sidemounted pump and release mechanisms thereof will remain at convenient and readily accessible locations irrespective of the relative position of the pivotally mounted hydraulic cylinder. This is accomplished by provision of the novel pump and release mechanisms which act through opposed, oppositely extending, axially bored mounting trunnions connected to the base of the jack for the purposes described. Moreover, the unique pump andrelease structure utilized, in conjunction with the tension link lift arm design, reduces both the size and weight of the complete jack. For example, the jack depicted in the drawings weighs approximately 36 pounds and has a 1% ton lifting capacity, while prior service jacks of equal lifting capacity have often weighed up to twice as much.

Furthermore, potential problems which could be encountered with a side-mounted pump mechanism as disclosed herein by virtue of laterally directed forces imposed upon the jack during pumping are effectively precluded in thepresent construction because of the unique release mechanism utilized. In particular, during the pumping sequence with the side-mounted pump of the present invention, maximum hydraulic pressures on the order of 8,000 to 10,000 psi act on the rotary seal at the pump side of the cylinder assembly. These pressures can force the cylinder assembly toward the left side of the jack as viewed in FIG. 7. The actual motion is in all cases slight, perhaps to 20 thousandths of an inch, and varies with pressure. However, if the release trunnion 100 and associated manipulative mechanism 282 were positively secured to the frame, this lateral cylinder motion culd adversely affect release action, as axial motion of this same magnitude is required to lower or hold the load. .Hence, by provision of a pivotable release mechanism having an associated manipulative mechanism which is free to move trans versely to a limited degree with cylinder 96 as described, problems of untoward jerking or other release motions are effectively precluded.

Having thus described the invention, what is claimed as new and desired to be secured by Letters Patent is:

1. A jack for raising objects, comprising: a frame; a supply of hydraulic fluid; a hydraulic cylinder having a pressure chamber and an axially reciprocable ram which extends outwardly therefrom and reciprocates in response to hydraulic pressure within said pressure chamber; selectively actuatable pump-means located adjacent said cylinder in side-by-side relationship therewith and operatively connected to said supply of hydraulic fluid; an elongated, axially bored trunnion operatively connected adjacent the ends thereof to said cylinder and pump means respectively, said trunnion being rotatably supported by said frame to define a pivot axis for said cylinder, there being hydraulic fluid passageways in said cylinder communicating said pressure chamber and trunnion bore, the latter and said fluid passageways communicating said pump means and pressure chamber, said pump means being operable to draw hydraulic fluid from said supply thereof and deliver the same under pressure through said trunnion bore and fluid passageways to said pressure chamber; lift structure including a lift arm pivotally secured to said frame, and object engaging structure on said lift arm, said ram being operatively connected to said lift structure at a point on the latter spaced from the pivotal securement thereof to effect raising and lowering of said lift structure as said ram reciprocates; and selectively actuatable release mechanism operatively connected to said cylinder for relieving the hydraulic pressure within said pressure chamber to permit lowering of said jack.

2 .'The jack as set forth-in claim 1, wherein said frame includes a pair of spaced side members with said cylinder pivotally secured therebetween, said pump means being positioned proximal to one of said side members adjacent the face thereof remote from said'cylinder.

3. The jack as set forth in claim 2, wherein said trunnion is releasably secured to said cylinder at the innermost end thereof and is rotatably mounted at the opposite end thereof in said pump means, the latter being fixedly secured to said one side member on the face thereof remote from said cylinder, whereby as said cylinder pivots during raising of said jack, said trunnion rotates therewith with respect to said one side member and pump means.

4. The jack as set forth in claim 1, wherein said cylinder is an elongated, hollow member including a hydraulic fluid reservoir holding said supply thereof, and a pressure chamber, said ram being coaxial with said cylinder and extending from said pressure chamber, said cylinder having a base section connected to said reservoir and chamber respectively, said base section being bored to define hydraulic fluid passageways communicating said reservoir and chamber respectively, said axial trunnion bore being in communication with said passageways, the latter and'said trunnion bore defining a fluid path for drawing of hydraulic fluid from said reservoir to said pump means, and return of said fluid back through said trunnion bore under pressure to said pressure chamber to effect raising of said jack.

5. The jack as set forth in claim 4, wherein said base section is provided with a primary bore and spaced secondary bores communicating the same with said hydraulic fluid reservoir and pressure chamber respectively, said primary bore being in communication with said trunnion bore, there being valve structure in said primary bore operable to direct hydraulic fluid to said trunnion bore and thence to said pump when the latter is actuated to draw said fluid from said reservoir, said valve structure also being operable to direct hydraulic fluid under pressure returning through said trunnion bore from said pump means to said pressure chamber to effect raising of said jack.

6. The jack as set forth in claim 2, wherein said pump includes a pump block fixedly secured to said one side member on the face thereof remote from said cylinder, said block having an elongated plunger bore therein in communication with said trunnion bore, there being a reciprocable plunger telescopically received within said plunger bore with external means connected thereto for effecting reciprocation thereof, whereby, as said external means is manipulated to partially withdraw said plunger from said plunger bore, hydraulic fluid is drawn from said supply thereof and into said plunger bore, and as said external means is manipulated to force said plunger bac'kinto said plunger bore, hydraulic fluid under pressure is forced from said plunger bore through said trunnion bore and thence to said cylinder to effect raising of said jack.

7. The jack as set forth in claim 1, wherein said ram and lift arm are interconnected proximal to the respective outermost ends thereof.

8. The jack as set forth in claim 7, wherein said object-engaging structure comprises a lift pad pivotally secured to said lift arm at the outermost end thereof, said lift arm and ram both being secured by a single transverse wrist pin connected to said'lift pad.

9. The jack as set forth in claim 1, said selectively actuatable release mechanism operatively being connected to said cylinder at a point remote from the connection of said pump means.

10. A jack for raising objects, comprising; a frame;

asupply of hydraulic fluid;

a hydraulic cylinder having a pressure chamber and an axially reciprocable ram which extends outwardly therefrom and reciprocates in response to hydraulic pressure within said pressure chamber;

selectively actuatable pump means operatively connected to said cylinder and supply of hydraulic fluid for selectively drawing fluid from the latter and delivering the same under pressure to said pressure chamber;

an elongated, axially bored trunnion mounted adjacent one end thereof to said cylinder and rotatably supported by said frame to define a pivot axis for said cylinder;

manipulative means mounted adjacent the remaining end of said trunnion;

means communicating said pressure chamber and supply of hydraulic fluid for permitting return flow of hydraulic fluid from the pressure chamber to the supply thereof;

means carried within the axial bore of said trunnion which is operable to preclude said return flow of hydraulic fluid through said communicating means and actuatable by said manipulative means to permit said return flow of hydraulic fluid; and

lift structure including a lift arm pivotally secured to said frame, and object-engaging structure on said lift arm,

said ram being operatively connected to said lift structure at a point on the latter spaced from the pivotal securement thereof to effect raising and lowering of said lift structure as said ram reciprocates.

11. The jack as set forth in claim 10, wherein said frame includes a pair of spaced side member with said cylinder pivotally secured therebetween, said manipulative means being positioned proximal to one of said member adjacent the face thereof remote from said cylinder.

12. The jack as set forth in claim 11, wherein said trunnion is secured at the innermost end thereof to said cylinder and is freely rotatable with respect to said manipulative means at the outermost end thereof, there being mens for precluding rotation of said manipulative means with said trunnion, whereby as said cylinder pivots during raising and lowering of said jack, said trunnion rotates with respect to said one side member and manipulative means.

13. The jack as set forth in claim 10, wherein said cylinder includes a base section, said trunnion being operatively connected at the innermost end thereof to said base section, the latter being bored to define hydraulic fluid pasageways communicating said pressure chamber and trunnion bore respectively, said trunnion bore being in communication with said supply of hydraulic fluid, there being a shiftable release element within said trunnion bore movable by said manipulative means between a first position blocking communication between said supply and pressure chamber, and a second release position permitting flow of hydraulic fluid therebetween.

14. The jack as set forth in claim 13, wherein said manipulative means is fixedly secured to remain stationary during pivoting movement of said trunnion, said manipulative means includng selectively actuatable mechanism for engaging the outermost end of said release element within said trunnion bore for moving said element axially between the second and first positions thereof.

15. The jack as set forth in claim 14, wherein said mechanism comprises support structure rotatably mounted over the outermost end of said trunnion, there being means precluding rotation of said support structure with the trunnion, and a release screw carried by said support structure generally perpendicularly of said release element and proximal thereto, there beng a conical portion along the length of said screw in engagement with the outermost end of said release element, whereby as said release screw is advanced, said conical section thereon progressively axially displaces said release element to move the same to the first position thereof.

16. The jack as set forth in claim 13, wherein said trunnion bore has a section thereof of reduced diameter at the innermost end thereof, said release element being freely rotatable within said bore and being of configuration at the innermost end thereof to sealingly engage said reduced diameter end of said trunnion bore when said element is in the first position thereof.

17. The jack as set forth in claim 16, wherein said trunnion includes a transversely extending aperture therein spaced outwardly from said innermost end and extending through the sidewall thereof, there being a hydraulic fluid passageway communicating said transverse aperture and said supply of hydraulic fluid, said aperture and passageway defining a fluid path for return flow of hydraulic fluid from said pressure chamber, through said trunnion bore and transverse aperture, and thence to said supply, said release element being dimensioned to permit flow therepast to said transverse aperture when the element is in the second position thereof.

18. The jack as set forth in claim 17, wherein said trunnion is releasably secured to the base section of said cylinder.

19. The jack as set forth in claim 12, wherein said re- I lease element is a segmented rod comprising an outermost, elongated cylindrical portion, and a separate innermost portion having a conical leading surface, there being a spacer ball between said outermost and innermost portions.

20. The jack as set forth in claim 10, wherein said ram and lift arm are interconnected proximal to the respective outermost ends thereof.

21. The jack as set forth in claim 20, wherein said object-engaging structure comprises a lift pad pivotally secured to said lift arm at the outermost end thereof, said lift arm and ram both being secured to a single transverse wrist pin connected to said lift pad.

22. The jack as set forth in claim 10 wherein said trunnion bore is in communication with said supply of hydraulic fluid and pressure chamber respectively, said means carried within sid axial bore being operable to permit said return flow of hydraulic fluid through at least a portion of said trunnion bore.

23. The jack as set forth in claim 22 wherein said cylinder is an elongated, hollow member including a hydraulic fluid reservoir holding said supply thereof, and a pressure chamber, said ram being coaxial with said cylinder and extending from said pressure chamber, said cylinder having a base section connected to said reservoir and chamber respectively, said trunnion being connected to said base section, the latter being bored to define hydraulic fluid passageways communicating said reservoir and pressure chamber through at least a part of said axial trunnion bore, the latter being in communication with said passageways; said trunnion bore and passageways defining a fluid. pathfor return flow of hydraulicfluid from said pressure chamber to said reservoir when said release element is in the second release position thereof.

24. The jack as set forth in claim 23, wherein said base section is provided with a primary bore and a first duct communicating said reservoir and trunnion, said trunnion having a transverse aperture therein communicating the bore thereof with said first duct, there being a hydraulic fluid passageway communicating said trunnion bore and primary bore, and a second duct communicating said primary bore with said pressure chamber, said axial trunnion borebeing of reduced diameter at the end thereof connected to said cylinder, said release element having an innermost end adjacent said reduced diameter end of said trunnion bore configured to sealingly engage with the inner face of said reduced diameter end to preclude fluid flow through said axial trunnion bore when said rod is in the first position thereof to thereby prevent lowering of said jack.

25. A jack for raising objects, comprising:

a frame;

a hydraulic cylinder having a pressure chamber and an axially reciprocable ram which extends outwardly therefrom and reciprocates in response to hydraulic pressure within said pressure, chamber;

a supply of hydraulic fluid;

first and second elongated, axially bored, oppositely extending trunnions secured adjacent the respective innermost'ends thereof to said cylinder on opposite sides of the latter, said first and second trunnions being substantially coaxially aligned and rotatably supported by said frame to cooperatively define a pivot axis for said cylinder;

selectively actuatable pump means operatively connected to said supply of hydraulic fluid for drawing liquid from the latter and pressurizing the same, and mounted adjacent said first trunnion with the bore of the latter and said pump means being in operative communication;

means communicating said first trunnion bore and pressure chamber for permitting flow of pressurized hydraulic fluid to the latter from said pump means;

release mechanism operatively connected through said second trunnion bore to said last mentioned communicating means for selectively relieving the hydraulic pressure within said chamber and permitting said return flow,

said release mechanism including manipulative means for selectively actuating the same to relieve said pressure, said manipulative means being mounted adjacent said second trunnion; and

lift structure including a lift arm pivotally secured to said frame, and object engaging structure on said lift arm,

frame includes a pair of spaced side members, said first and second trunnions ea'ch extending through the corresponding" adjacent side member and being rotatable with respect to'th same.

27. The jack 'as' set forth in claim 26, said pump means being fixedly'secured to said side member adjacent said first trunnion on'the face thereof remote from said cylinder, the outermost end of said first trunnion being'operatively connected and rotatable with respect thereto, the base section of said cylinder being bored to provide hydraulic fluid passageways communicating said first trunnion bore with said pre ssure chamber to permit flow of pressurized fluid from said pump means through said first trunnion bore to said pressure chartiber, to thereby raise said jack. 7 i

v 28. The jack as set forth in claim 27, wherein said manipulative means is located adjacent the face or the other of said side members remote from said cylinder, and against rotation with respectto said other side member, the outermost end of said second trunnion being rotatable with respect to said limanipulative means, said release mechanism including an ,elongated release element carried within the second trunnion bore, said second trunnion bore beingin communication with said supply of hydraulic fluid andsaid pressure chamber respectively, said element beingshiftable in response to manipulation of saidmanipulative means for permitting return flow of hydraulic fluid from said pressure chamber through at least a portion of said second trunnion bore to said supply of hydraulic fluid, to thereby permit lowering of said.jack.,

29. A jack for raising objects, comprising:

a frame;

a hydraulic cylinder pivotally secured to said frame,

said cylinder having a pressure chamber and an axially reciprocable ram which extends outwardly therefrom and reciprocates in response to hydraulic pressure within said pressure chamber;

lift structure including a lift arm pivotally secured to said frame, and object engaging structure mounted on said lift arm,

said ram being operatively connected to said lift structure at a point on the latter remote from the pivotal securement thereof to effect raising and lowering of said lift structure as said ram reciprocates;

a supply of hydraulic fluid;

selectively actuatable pump means operatively connected to said cylinder and supply of hydraulic fluid for selectively drawing fluid from the latter and delivering the same under pressure to said pressure chamber to thereby raise said lift structure as said cylinder pivots upwardly; and

selectively actuatable release mechanism operatively connected to said cylinder for relieving the hydraulic pressure within said pressure chamber to permit lowering of said jack,

said pump and release mechanism being positioned on opposite sides of said cylinder,

said release mechanism having manipulative means forming a part thereof for actuating the same to relieve said hydraulic pressure, said release mechanism and manipulative means being secured to said cylinder and free of said frame to permit the release mechanism and manipulative means to shift 19 laterally in unison with the cylinder and with respect to the frame. I

30. The jack as set forth in claim 29, wherein said release mechanism comprises an elongated, axially bored trunnion secured to said cylinder and defining the pivot axis thereof, said trunnion being pivotally mounted in said frame to rotate with said cylinder as the latter pivots, said trunnion being free to move laterally to a slight degree with respect to said frame, said cylinder being bored to provide hydraulic fluid passageways communicating the pressure chamber thereof with said trunnion bore, the latter also being in communication with said supply of hydraulic fluid, there being a release element carried within said trunnion bore shiftable between a first position blocking return flow of hydraulic fluid from said pressure chamber through at least a part of said trunnion bore to said supply thereof, and a second position permitting said return flow, there being manipulative means pivotally secured about said trunnion adjacent the outermost end thereof for selectively moving said release rod between the second and first positions thereof, and means precluding rotation of said manipulative means with said trunnion during pivotal movement of the latter.

31. The jack as set forth in claim 30, wherein said release element is an axially shiftable release rod, the latter being freely rotatable within said trunnion bore and with respect to said manipulative means.

32. A'jack for raising objects, comprising:

a frame;

a'supply of hydraulic fluid;

a hydraulic cylinder including a hydraulic fluid reservoir holding said supply thereof, a pressure chamber, and a ram which extends outwardly from the pressure chamber and reciprocates in response to hydraulic pressure within said pressure chamber, said cylinder being bored to define hydraulic fluid passageways communicating said reservoir and chamber respectively;

an elongated, axially bored trunnion operatively connected adjacent the innermost end thereof to said cylinder and rotatably supported by said frame to define a pivot axis for said cylinder;

selectively actuatable pump means secured adjacent the outermost end of said trunnion and in communication with the bore thereof;

said trunnion bore and fluid passageways being in communication and defining a fluid path for drawing of hydraulic fluid from said reservoir to said pump means, and return of said fluid back through said trunnion bore under pressure to said pressure chamber to effect raising of said jack;

said ram being operatively connected to said lift structure at a point on the latter spaced from the pivotal securement thereof to affect raising and lowering of said lift structure as said ram reciprocates; and

selectively actuatable release mechanism operatively connected to said cylinder for relieving the hydraulic pressure within said pressure chamber to permit lowering of said jack.

Claims

2. The jack as set forth in claim 1, wherein said frame includes a pair of spaced side members with said cylinder pivotally secured therebetween, said pump means being positioned proximal to one of said side members adjacent the face thereof remote from said cylinder.

4. The jack as set forth in claim 1, wherein said cylinder is an elongated, hollow member including a hydraulic fluid reservoir holding said supply thereof, and a pressure chamber, said ram being coaxial with said cylinder and extending from said pressure chamber, said cylinder having a base section connected to said reservoir and chamber respectively, said base section being bored to define hydraulic fluid passageways communicating said reservOir and chamber respectively, said axial trunnion bore being in communication with said passageways, the latter and said trunnion bore defining a fluid path for drawing of hydraulic fluid from said reservoir to said pump means, and return of said fluid back through said trunnion bore under pressure to said pressure chamber to effect raising of said jack.

6. The jack as set forth in claim 2, wherein said pump includes a pump block fixedly secured to said one side member on the face thereof remote from said cylinder, said block having an elongated plunger bore therein in communication with said trunnion bore, there being a reciprocable plunger telescopically received within said plunger bore with external means connected thereto for effecting reciprocation thereof, whereby, as said external means is manipulated to partially withdraw said plunger from said plunger bore, hydraulic fluid is drawn from said supply thereof and into said plunger bore, and as said external means is manipulated to force said plunger back into said plunger bore, hydraulic fluid under pressure is forced from said plunger bore through said trunnion bore and thence to said cylinder to effect raising of said jack.

8. The jack as set forth in claim 7, wherein said object-engaging structure comprises a lift pad pivotally secured to said lift arm at the outermost end thereof, said lift arm and ram both being secured by a single transverse wrist pin connected to said lift pad.

10. A jack for raising objects, comprising; a frame; a supply of hydraulic fluid; a hydraulic cylinder having a pressure chamber and an axially reciprocable ram which extends outwardly therefrom and reciprocates in response to hydraulic pressure within said pressure chamber; selectively actuatable pump means operatively connected to said cylinder and supply of hydraulic fluid for selectively drawing fluid from the latter and delivering the same under pressure to said pressure chamber; an elongated, axially bored trunnion mounted adjacent one end thereof to said cylinder and rotatably supported by said frame to define a pivot axis for said cylinder; manipulative means mounted adjacent the remaining end of said trunnion; means communicating said pressure chamber and supply of hydraulic fluid for permitting return flow of hydraulic fluid from the pressure chamber to the supply thereof; means carried within the axial bore of said trunnion which is operable to preclude said return flow of hydraulic fluid through said communicating means and actuatable by said manipulative means to permit said return flow of hydraulic fluid; and lift structure including a lift arm pivotally secured to said frame, and object-engaging structure on said lift arm, said ram being operatively connected to said lift structure at a point on the latter spaced from the pivotal securement thereof to effect raising and lowering of said lift structure as said ram reciprocates.

19. The jack as set forth in claim 12, wherein said release element is a segmented rod comprising an outermost, elongated cylindrical portion, and a separate innermost portion having a conical leading surface, there being a spacer ball between said outermost and innermost portions.

23. The jack as set forth in claim 22 wherein said cylinder is an elongated, hollow member including a hydraulic fluid reservoir holding said supply thereof, and a pressure chamber, said ram being coaxial with said cylinder and extending from said pressure chamber, said cylinder having a base section connected to said reservoir and chamber respectively, said trunnion being connected to said base section, the latter being bored to define hydraulic fluid passageways communicating said reservoir and pressure chamber through at least a part of said axial trunnion bore, the latter being in communication with said passageways, said trunnion bore and passageways defining a fluid path for return flow of hydraulic fluid from said pressure chamber to said reservoir when said release element is in the second release position thereof.

24. The jack as set forth in claim 23, wherein said base section is provided with a primary bore and a first duct communicating said reservoir and trunnion, said trunnion having a transverse aperture therein communicating the bore thereof with said first duct, there being a hydraulic fluid passageway communicating said trunnion bore and primary bore, and a second duct communicating said primary bore with said pressure chamber, said axial trunnion bore being of reduced diameter at the end thereof connected to said cylinder, said release element having an innermost end adjacent said reduced diameter end of said trunnion bore configured to sealingly engage with the inner face of said reduced diameter end to preclude fluid flow through said axial trunnion bore when said rod is in the first position thereof to thereby prevent lowering of said jack.

25. A jack for raising objects, comprising: a frame; a hydraulic cylinder having a pressure chamber and an axially reciprocable ram which extends outwardly therefrom and reciprocates in response to hydraulic pressure within said pressure chamber; a supply of hydraulic fluid; first and second elongated, axially bored, oppositely extending trunnions secured adjacent the respective innermost ends thereof to said cylinder on opposite sides of the latter, said first and second trunnions being substantially coaxially aligned and rotatably supported by said frame to cooperatively define a pivot axis for said cylinder; selectively actuatable pump means operatively connected to said supply of hydraulic fluid for drawing liquid from the latter and pressurizing the same, and mounted adjacent said first trunnion with the bore of the latter and said pump means being in operative communication; means communicating said first trunnion bore and pressure chamber for permitting flow of pressurized hydraulic fluid to the latter from said pump means; means communicating said pressure chamber and supply of hydraulic fluid for permitting return flow of hydraulic fluid from the pressure chamber to the supply thereof; release mechanism operatively connected through said second trunnion bore to said last mentioned communicating means for selectively relieving the hydraulic pressure within said chamber and permitting said return flow, said release mechanism including manipulative means for selectively actuating the same to relieve said pressure, said manipulative means being mounted adjacent said second trunnion; and lift structure including a lift arm pivotally secured to said frame, and object engaging structure on said lift arm, said ram being operatively connected to saiD lift structure at a point on the latter spaced from the pivotal securement thereof to effect raising and lowering of said lift structure as said ram reciprocates.

26. The jack as set forth in claim 25 wherein said frame includes a pair of spaced side members, said first and second trunnions each extending through the corresponding adjacent side member and being rotatable with respect to the same.

27. The jack as set forth in claim 26, said pump means being fixedly secured to said side member adjacent said first trunnion on the face thereof remote from said cylinder, the outermost end of said first trunnion being operatively connected and rotatable with respect thereto, the base section of said cylinder being bored to provide hydraulic fluid passageways communicating said first trunnion bore with said pressure chamber to permit flow of pressurized fluid from said pump means through said first trunnion bore to said pressure chamber, to thereby raise said jack.

28. The jack as set forth in claim 27, wherein said manipulative means is located adjacent the face of the other of said side members remote from said cylinder, and against rotation with respect to said other side member, the outermost end of said second trunnion being rotatable with respect to said manipulative means, said release mechanism including an elongated release element carried within the second trunnion bore, said second trunnion bore being in communication with said supply of hydraulic fluid and said pressure chamber respectively, said element being shiftable in response to manipulation of said manipulative means for permitting return flow of hydraulic fluid from said pressure chamber through at least a portion of said second trunnion bore to said supply of hydraulic fluid, to thereby permit lowering of said jack.

29. A jack for raising objects, comprising: a frame; a hydraulic cylinder pivotally secured to said frame, said cylinder having a pressure chamber and an axially reciprocable ram which extends outwardly therefrom and reciprocates in response to hydraulic pressure within said pressure chamber; lift structure including a lift arm pivotally secured to said frame, and object engaging structure mounted on said lift arm, said ram being operatively connected to said lift structure at a point on the latter remote from the pivotal securement thereof to effect raising and lowering of said lift structure as said ram reciprocates; a supply of hydraulic fluid; selectively actuatable pump means operatively connected to said cylinder and supply of hydraulic fluid for selectively drawing fluid from the latter and delivering the same under pressure to said pressure chamber to thereby raise said lift structure as said cylinder pivots upwardly; and selectively actuatable release mechanism operatively connected to said cylinder for relieving the hydraulic pressure within said pressure chamber to permit lowering of said jack, said pump and release mechanism being positioned on opposite sides of said cylinder, said release mechanism having manipulative means forming a part thereof for actuating the same to relieve said hydraulic pressure, said release mechanism and manipulative means being secured to said cylinder and free of said frame to permit the release mechanism and manipulative means to shift laterally in unison with the cylinder and with respect to the frame.

32. A jack for raising objects, comprising: a frame; a supply of hydraulic fluid; a hydraulic cylinder including a hydraulic fluid reservoir holding said supply thereof, a pressure chamber, and a ram which extends outwardly from the pressure chamber and reciprocates in response to hydraulic pressure within said pressure chamber, said cylinder being bored to define hydraulic fluid passageways communicating said reservoir and chamber respectively; an elongated, axially bored trunnion operatively connected adjacent the innermost end thereof to said cylinder and rotatably supported by said frame to define a pivot axis for said cylinder; selectively actuatable pump means secured adjacent the outermost end of said trunnion and in communication with the bore thereof; said trunnion bore and fluid passageways being in communication and defining a fluid path for drawing of hydraulic fluid from said reservoir to said pump means, and return of said fluid back through said trunnion bore under pressure to said pressure chamber to effect raising of said jack; lift structure including a lift arm pivotally secured to said frame, and object engaging structure on said lift arm, said ram being operatively connected to said lift structure at a point on the latter spaced from the pivotal securement thereof to affect raising and lowering of said lift structure as said ram reciprocates; and selectively actuatable release mechanism operatively connected to said cylinder for relieving the hydraulic pressure within said pressure chamber to permit lowering of said jack.