US3780987A

US3780987A - Low profile jack for fork lift trucks

Info

Publication number: US3780987A
Application number: US00161191A
Authority: US
Inventors: R Craft; G Gaarder
Original assignee: Gray Manufacturing Co Inc
Current assignee: Gray Automotive Products Co
Priority date: 1971-07-09
Filing date: 1971-07-09
Publication date: 1973-12-25
Anticipated expiration: 1990-12-25
Also published as: CA968779A

Abstract

A low profile lifting jack having a walking beam frame with an object-engaging lifting member that travels in an arcuate path upwardly and forwardly toward the vehicle being lifted during the power stroke of the jack. A lift pad carried on the lifting member is movable between two positions presenting concavo-convex surfaces respectively for engagement with the vehicle being lifted. A permanently attached manual handle operates a fluid actuator integrally carried on the jack and is pivotal between a position facilitating transporting the jack, and another horizontal position for storage. The fluid actuator folds from a vertical operating position to a low, generally horizontal storing and carrying position.

Description

United States Patent [191 Craft et al.

[ LOW PROFILE JACK FOR FORK LIFl TRUCKS [75] Inventors: Roger L. Craft; Gilbert W. Gaarder,

both of St. Joseph, Mo.

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

52 us. Cl. 254/8 R, 254/122, 254/133 R 51 Int. c1 B60p 1/48, B66f 3/22 [58] Field o f Search., 254/s-10, 93 R, 93 L,

[56] References Cited UNITED STATES PATENTS 9/ 1936 White 6/1967 Jenkins 4/1968 Rapp If. 2s4/93 R 1 Dec. 25, 1973 Primary Examiner-Othell M. Simpson Attorney-Schmidt, Johnson, l-lovey & Williams ABSTRACT A low profile lifting jack having a walking beam frame with an object-engaging lifting member that travels in an arcuate path upwardly and forwardly toward the vehicle being lifted during the power stroke of the jack. A lift pad carried on the lifting member is movable between two positions presenting concavoconvex surfaces respectively for engagement with the vehicle being lifted. A permanently attached manual handle operates a fluid actuator integrally carried on the jack and is pivotal between a position facilitating transporting the jack, and another horizontal position for storage. The fluid actuator folds from a vertical operating position to a low, generally horizontal storing and carrying position.

34 Claims, 7 Drawing Figures PATENTED DEB 2 5 I973 "a 50 m4 615 a? LOW PROFILE JACK FOR FORK LIFT TRUCKS This invention relates to jacks for lifting vehicles or other heavy machinery.

Upon being lifted, vehicles or other heavy objects will tilt about their opposite edges on ground contact points and thereby cause horizontal travel of the lift point. In following this'natural rising arc of the vehicle, particularly wheneveriengaging and lifting the vehicle from its side or comer a lifting jack will also be subject to a certain amount of horizontal travel toward the vehicle. In attempting to compensate for this horizontal movement, jacks normally must sacrifice stability characteristics and are, as aresult, subject to slippage either at its contact with the vehicle or at its contact with the floor support surface. Such slippage is quite dangerous of course, for both the operator and the machinery being lifted. A typical example of such arrangement is a jack completely supported on wheels to roll horizontally with the vehicle; however, this nonstationary support renders the jack highly susceptible to slipping, rolling, and consequently dropping the load. Certain types of vehicles, such as forklift trucks, have low ground clearances requiring a jack quite low in profile capable of sliding underneath the truck to a position engageable with its undercarriage frame. Yet these trucks are quite heavy and normally require a large, powerful lift. As a result of these and other problems, transportable manual jacks of conventional design have been found unsafe and generally unacceptable for use with such vehicles.

To obviate these and other difficulties it is, therefore, the primary object of the present invention to provide an improved lifting jack.

It is an object of the invention to provide a jack of great lifting capacity for safely lifting vehicles or machinery having low ground clearances.

. An important object of the invention is to provide a lightweight, compact, yet rugged jack that can be carried or wheeled with ease.

Yet another object of the invention is to provide a jack having a versatile contact pad arrangement accommodating either flat undersurfaces, tubular members or protruding edges of vehicle structural undercarriages.

Still another object is to provide a jack in accordance with the preceding objects that is manually operated and has efficient, power multiplying means integrally carried on the jack.

A very important object of the invention is to provide a jack arranged whereby its lifting point of contact travels in an arcuate path following the natural arc of the object being lifted while providing substantially stationary, solid footing for the vehicle and jack during lifting.

It is an important object of the invention to provide .a lifting jack having a raising member moving arcuately upwardly and forwardly toward the device being lifted, and that is carried by a support member maintained in firm, gripping, essentially nonsliding engagement with the jack-supporting surface throughout the lifting operation.

Another object in accordance with the preceding object is to provide a jack having lift and support members pivotally attached to one another in cross relationship with the support member firmly contacting the jack support surface at a position farther from the pivot axis than the position of engagement of the lifting member with the object being raised.

A further object of the invention is to provide a jack frame having a pair of arms pivotally secured to one another so as to rotate in a scissors action during the power stroke of the jack and wherein the objectengaging arm of the jack frame is shorter than the arm of the frame engaging the support surface.

Another object of the invention is to provide a fluidoperated lifting jack having a permanently attached fluid actuator rotatable between a vertical operating position and a horizontal storing position, and a jackoperating handle pivotally secured to the fluid actuator so as to rotate between one position operating the actuator and another generally horizontal storage position.

Still another object of the invention is to provide a mobile fluid-operated jack having a permanently attached fluid actuator and positive displacement pump, and operating means permanently secured to the jack that is rotatable between a position operating the pump, another position extending from the jack to facilitate transporting the jack, and a third generally horizontal position for storing or carrying.

A more particular object in accordance with the preceding object is to provide operating means which include a lever pivotally attached to the actuator and a manual handle telescopically received by the lever to rotate therewith and shift radially relative thereto into and out of operative engagement with the fluid pump.

Yet another object of the invention is to provide a jack having a lift pad that is shiftable between two positions respectively presenting concavo and convex surfaces for objecblifting engagement, and detent means carried on the jack for holding the lift pad in the selected position.

Yet another object of the invention is to provide a versatile life jack arranged having a very low profile frame when collapsed, and a vertically extensible, integral fluid actuator and pump assembly carried on the frame adapted to swing parallel to the collapsed frame for storing or carrying.

Still a further object in accordance with the preceding object is to provide a manual pump-operating handle that also acts as a rigid jack-transporting handle, and which is rotatable to a generally horizontal disposition parallel to the jack frame for storing.

Briefly, the preferred form of the invention comprises a jack having scissors-arranged frame arms with a forward end of one arm in firm, gripping supporting engagement with the ground. The other arm has a shorter, forward portion provided with selectable concave and convex surfaces for engaging a load and a rearward portion with a jack transporting wheel that is,

in rolling engagement with the ground. Carried by this walking beam-type frame is a vertically extending fluid actuator, rotatable to a low horizontal storing position, that strokes vertically to urge the object-engaging lifting surface arcuately upwardly and forwardly. A manual handle is pivotally attached to the fluid actuator so as to operate a positive displacement fluid pump that delivers motive fluid to the fluid actuator. The jack handle is also rotatable to a low, generally horizontal storing position as well as to a third position wherein it acts as an elongated, rigid lever facilitating rolling of the jack on its rear wheels.

These and other objects and advantages of the invention are specifically set forth in, or will become apparent from the following detailed description of a preferred embodiment of the invention and the accompanying drawings, in which:

FIG. 1 is a side elevational view of a jack constructed in accordance with the invention;

FIG. 2 is a top elevational view of the jack;

FIG. 3 is an enlarged, fragmentary, top elevational view of the fluid actuator and handle with a portion of the handle shown in cross section;

FIG. 4 is a transverse, partial cross-sectional view taken along line 4-4 of FIG. 3;

FIG. 5 is an enlarged, fragmentary view of the objectengaging portion of the jack with the lift pad positioned to present a convex lifting surface;

FIG. 6 is an enlarged, fragmentary view similar to FIG. 5 with the lift pad in a position presenting a concave lifting surface; and

FIG. 7 is a perspective view of the jack in folded configuration.

Referring now to the drawings and, more particularly to FIGS. 1 and 2 which show a jack assembly generally referred to by the numeral 10, the jack includes in its overall construction a pair of

frame members

12 and 14, pivotally secured in crossing, scissors-like relationship. During operation, these frame members pivot in opposite directions relative to one another about a frame pivotal axis defined by a trunnion mounting 16 which interconnects the members intermediate their ends so as to define

member arms

18, 20, 22 and 24 located at opposite sides of the frame pivotal axis and trunnion mounting 16.

An actuator assembly 26 (described in greater detail below) rotatably secures to the frame arms and 24 extending rearwardly, rightwardly in FIG. 1, from trunnion 16 and acts to rotate the

frame members

12 and 14 relatively oppositely about trunnion 16 to effect raising of the frame

upper arms

20 and 22. The forward upper arm 22 of object-engaging frame member 14 is disposed to engage the object to be lifted, while the adjacent lowermost end of forward arm 18 rests at a support position 32 on a support surface depicted by line 34 so that member 12 acts as a reaction member for supporting at position 32 the load experienced by forward lift arm 22. Accordingly, during jack operation, frame member 12 rotates about position 32 while framemember 14 rotates about trunnion 16 to create scissors-like opening and closing action of the frame members relative to each other.

Support member 12 is comprised of a pair of parallel, elongated beam-type levers 12a and 12b intersecured in spaced relationship by one or more frame cross members 36. The lift member 14, also formed as a generally elongated beam, is carried in the space formed between support levers 12a and 12b. Trunnion connection 16 includes a cylindrical pin firmly attached to support levers 12a and 12b that extends transversely across the frame member 14 through an aperture therein to pivotally interconnect the frame members.

A ground reaction pad 38, acting also as a frame cross support, extends in transverse attaching relationship at the lowermost ground-engaging ends of support levers 12a and 12b. Pad 38 presents a curved or arcuately formed surface at end 32 in firm, gripping engagement with the support surface 34. The lowermost end of frame member 14 has a wheel attached thereto and adapted to roll free on the support surface. In the preferred form, the ground-engaging surface of pad 38 is transversely grooved for increasing frictional contact with the ground so as to provide solid footing and greater stability for the jack. The convex surface of pad 38 facilitates slight rolling upon surface 34 as the jack operates and frame member 12 rotates about position 32, whileaffording maximum contact surface area with the support surface to prevent any horizontal sliding or slippage of the jack upon surface 34. The radius of curvature of the support-surface-engaging surfaces of the wheel 40 and ground reaction pad 38 are essentially equal to assure pure rolling contact of both the wheel and pad with the support surface. The support position 32 of reaction pad 38 will move a limited distance horizontally and leftwardly with respect to FIG. 1 during the relative pivoting of

frame members

12 and 14.

Lift member 14 carries an object-engaging lifting pad 42 at the upper end of its forward arm 22 and has jacktransporting wheels 40 attached at the lowermost end of its rearwardly positioned arm 24 in rolling contact with the support surface. Object-engaging lifting pad 42, shown in greater detail in FIGS. 5 and 6, has an external, convexly formed object-gripping surface 44, an oblong closed aperture 46, and oblong depressions 48, one of which is shown. A transversely disposed pin formed on upper lift arm 22 is relatively loosely received within pad closed aperture 46 to shiftably mount pad 42 upon the lift arm. Pad 42 is manually shiftable to the first position shown in FIG. 5 wherein a pair of cylindrical detenting studs 52 (shown by dashed lines in FIG. 2) and a plate stop member 54 engage the pad as shown to locate and hold surface 44 in an exposed, upwardly facing position. Surface 44 is transversely serrated for good gripping engagement with the object to be lifted and is of slightly convex configuration presenting maximum contact surface area for the object during rotation of frame member 14 about trunnion 16. Pad 42 is moved to its FIG. 6 position by sliding it upwardly and leftwardly as permitted by aperture 46 and dropping its depressions 48 over corresponding detent studs 52 which thereupon locate and positively hold the pad it its FIG. 6 position. Concavely arranged surface 56 formed at the upper end of upper lift arm 22 is now exposed for object-engagement as the frame upper lift arm 22 raises.

Concave surface 56 acts as a cradle for firmly engaging a narrow rail, edge or circular part of an object being raised, while convex surface 44 is best adapted for engaging a flat, plate-like surface portion of an object. Inclusion of lift pad 42 greatly adds to the versatility of jack 10 as the

surfaces

44 and 56 presented by pads 42 can firmly and nonslidingly contact any of a variety of surface configurations which may be presented by the vehicle. It will be apparent that the concave surface 56, shown at being disposed upon lift arm 22, may also be'formed upon lift pad 42 if desired.

The actuator assembly, 26 is of the hydraulic type comprising a cylinder 58 having a variable volume fluid chamber (not shown) and a longitudinally extending rod 60 exposed and operated by pressure fluid within the cylinder chamber. Cylinder 58 and a positive displacement pump 62 are secured to a mounting block 64 that has a trunnion fitting 28 facilitating permanent and pivotal coupling to rear support arm 20. Mounting block 64 has internal fluid circuitry (not shown) interconnecting the pump 62 with the actuating chamber of cylinder 58 so as to deliver motive fluid from the pump to the cylinder upon vertically stroking a pump connecting link 66. The rod 60 which depends downwardly through mounting block 64, is thereupon'forced to extend farther outwardly of cylinder 58 and thereby vertically displace its pivotal connection 30 with rear lift arm 24 from trunnion connection 28. A manually operable pressure release valve mechanism 68, mounted upon the easily accessible upper face 70 of cylinder 58, is operatively connected with the internal hydraulic circuitry so as to selectively relieve pressure from the cylinder actuating chamber to permit rod 60 to retract back into cylinder 58.

Rod-pivot pin 30 is carried in apertures in the rear lift arm 24 and rod 60 which are aligned upon positioning of actuator assembly 26 in its upright operating position shown in FIG. 1, and is selectively removable therefrom to permit rotation of the fluid actuator assembly 26 about trunnion connection 28 to a generally horizontal disposition (FIG. 7) for storing. When located in engagement with the rod 60 and rear lift arm 24, pin 30 acts in conjunction with trunnion connection 28-to lock the actuator assembly 26 in its vertical FIG. 1 position and confine rod 60 to reciprocate vertically. Pin 30 is removed to facilitate rotation of the actuator assembly 26 clockwise about pivot 28 from its upright operating position to its generally horizontal storing position. In this storing position, opening 72 in the mounting block 64 aligns with the pin-accepting aperture of arm 24 to permit reinsertion of pin 30 therethrough so as to lock the actuator assembly 26 in its horizontal storing disposition.

A manual jack-operating member generally referred to by the numeral 74, is pivotally carried upon cylinder 58 so as to be rotatable between a pump-operating position depicted in FIGS. 1, 3 and 4, a position facilitating transporting the jack illustrated in phantom in FIG. 4, and a generally horizontal storing position shown in FIG. 7. The operating member includes a pair of

identical levers

76 and 78 pivotally secured upon transversely extending trunnions 80 disposed on opposite sides of the cylinder 58. The

levers

76 and 78 comprise cylindrical bars extending radially from the pivotal axis formed by pin 80 to be telescopically received within a handle 82. Handle 82 is a hollow, tubular member having a U-shaped forward portion defining a pair of

parallel legs

84 and 8 6 that respectively accept

levers

76 and 78, and a radially extending lever arm 88 attached at the bottom of

legs

84 and 86. A manual gripping surface 90 is carried at the outer end of arm 88, and a hook latch 92 is attached upon arm 88 adjacent gripping surface 90.

Tension springs 94, one of which is shown in FIG. 3, are carried inside

tube legs

84 and 86 to be attached to the lever at point 96 and to a cross pin 98 firmly secured to the corresponding handle tube leg. Another cross pin 100 is guided in an opening 102 in lever 76 so as to permit limited inward and outward radial movement of the entire handle 82 relative to

levers

76 and 78. The bias of tension springs 94 urges the entire handle 82 radially inwardly toward the position depicted in FIG. 3.

The pump connection link 66, pivotally connected at point 67 to pump 62 is generally T-shaped and has a cross member 104 provided with sockets at either end for rotatively accepting a pair of lever arms 106 located between the handle levers 76 and 78. Arms 106 pivot at one end upon trunnion connection 80 and pivot upon cross member 104 at their other ends during vertical stroking of pump connecting link 66 and consequent jack lifting operation. The

handle legs

84 and 86 carry handle latching lugs 108-0n their inside surfaces for engagement with radially protruding bosses 110 on each lever arm 106. Lugs 108 lock upon bosses 110 when handle 82 is in its radial iwnard position depicted in FIGS. 3 and 4 to cause rotation of arms 106 and accompanying vertical stroking of connecting link 66 upon rotation of the entire operating member 74 about pivot 80. In such position of the handle, of course, manual rotation of handle 82 about pivot 80 is limited in relation to the vertical stroke length of pump 62.

While fluid actuator 26 is in its upright operating position of FIG. 1, the entire operating member 74 may be rotated to a generally vertical disposition extending above cylinder 58 upon pulling the handle radially outwardly to disengage lug 108 from boss I 10. In this handle position, the latch lugs 108 are urged radially inwardly by handle springs 94 to rigidly capture plate-like protrusions 112 formed on opposite sides of the exterior of cylinder 58 and thereby hold handle 82 in a disposition extending generally along the longitudinal axis of cylinder 58. The interengagement of lugs 108 with protrusions 112, as shown in phantom in FIG. 4, facilitates the use of handle 82 as a transporting member for rolling the entire jack on its wheels 40. In particular, upon securing rod 60 to rear lift arm 24 by pivot pin 30 and the handle lugs 108 to protrusions l 12, the rod 60, cylinder 58 and elongated handle 82 thereupon form an elongated lever firmly secured to the

jack frame members

12 and 14 so as to provide sufficient leverage to permit the entire jack to be tipped backwardly upon its wheel 40 to the position shown in phantom lines in FIG. 4. The reaction pad 38 is thereby lifted off of surface 34 so that the entire jack can easily be rolled and maneuvered upon wheels 40.

Jack operating member 74 is also adapted to rotate further counterclockwise from its engagement with protrusions 112 on cylinder 58 to the generally horizontal storing position shown in FIG. 7. Here, the operating handle 82 lies closely over and in juxtaposed relationship to the

frame members

12 and 14. The handle latch book 92 is now positioned to depend into the spaced apertures I14 and 116 opening onto the surface of frame member 14 now adjacent handle 82. Tension spring 94 again biases the handle inwardly in this position so as to securely lock handle 82 to frame member 14 by latch 92. Again, the handle is released from frame member 14 by manually pulling it radially outwardly with respect to trunnion connection 80 against the bias of tension spring 94. As clearly shown in FIG. 7, the handle 82 is angularly bent to facilitate grasping of the handle near the point 118 where handle arm 88 is affixed to the

tubular legs

84 and 86 to permit carrying of the jack much in the same manner as carrying a suitcase. The handle 82 is located in this folded storing configuration such that grasping point 118 lies near the center of gravity of the entire jack, whose

frame members

12 and 14 are collapsed to a quite low profile until member 12 engages a stop 120 formed on member 14. The jack, in consequence of its foldable frame, actuator and handle, presents a well-balanced, compact unit that can be conveniently carried with ease and that requires minimal storage space.

In operation of the jack, actuator assembly 26 is locked in its upright operation position by insertion of pin 30 through the aligned apertures in rod 60 and frame member 14. The handle 82 is located in its pumping position in operating engagement with pump connecting link 66, and lift pad 42 is shifted to select the desired lifting

surface

44 or 56. The jack, having its

frame members

12 and 14 initially in the low, closedprofile storing position, is maneuvered to position lift pad surface 42 and reaction pad 38 underneath and adjacent the object to be lifted and the free end of handle 82 at gripping surface 90 is stroked manually upwardly and downwardly. Pump 62 thereby displaces and forces motive fluid into cylinder 58 to force rod 60 to extend and vertically separate the

rear frame arms

20 and 24 from one another. As these rear arms are forced to separate in a scissors-like opening movement,

frame members

12 and 14 pivot relatively oppositely about pin 16 to cause the lift pad 42 to move in an upward direction so as to engage and lift the object, the reaction support surface 38 in firm gripping relationship with the support surface at support position 32.

The scissors arrangement of

frame member

12 and 14 form what may be referred to as a walking beam arrangement with a first lowermost end in relatively stationary, gripping engagement at a position 32 on the support surface 34, and with a second lowermost end, wheels 40, in relatively free moving engagement with the support surface. The jack is shown in a more raised position by phantom lines in FIG. 1, and it can be seen that the frame lowermost ends, support position 32 and wheels 40, travel forwardly in a horizontal direction generally toward the object engaged by lift pad 42. Lift pad 42 will, of course, move horizontally leftwardly with support position 32 as the latter executes its previously described leftward travel.

In addition, the preferred form of the invention contemplates further horizontal, leftward travel of lift pad 42 relative to the support position. It is important to note in this respect that forward lift arm 22 is substantially shorter than forward support arm 18 so that the lift surface presented by pad 42 is located substantially radially closer to the frame pivot 16 than is the support location 32 of the jack. Also, the distances from pivot pin 16 to respective lower ends of

arms

18 and 24 are essentially equal. This arrangement places lift pad 42at a location horizontally displaced from a vertical plane passing through support position 32. Accordingly, during operation of the jack, lift pad 42 not only raises upwardly, but also moves horizontally leftwardly toward the vertical plane containing the support location 32 of the jack, and consequently, moves generally forwardly with the vehicle being raised. Lift pad 42 thus travels horizontally a distance equal to the sum of its horizontal travel relative to support position 32 added with the horizontal travel of support position 32 itself.

In this manner, the lifting surface moves in an arcuate path following what may be termed the natural lifting arc of the object being raised. The vehicle engaged by pad 42 and being raised by the jack follows an arcuate path or natural lifting arc that may be roughly approximated as rotational movement of the vehicle about an axis passing through its opposite ground support point. The vehicle tilts or shifts slightly horizontally during vertical lifting, therefore, a sufficient distance as to require consonant horizontal travel of the jack at its point of lifting engagement in order to remain in supportive contact with the vehicle.

The jack of the present invention is accordingly structured so that a jack lift pad 42 follows the arcuate path of the lift point to remain in firm supporting contact with the vehicle. Lift pad 42, in traveling horizontally toward a vertical plane containing the fixed support location 32 due to the unequal length of jack forward

arms

18 and 22, moves horizontally forwardly (leftwardly in FIG. 1) toward the object being lifted to describe an arcuate lifting path generally approximating the natural lifting arc of the vehicle. In practice, these arcuate lifting paths are substantially linear, steep lines with horizontal travel being substantially less than vertical travel over the complete lifting stroke. It is an important part of the invention that, though lift pad 42 moves arcuately, reaction pad 38 remains in firm, gripping and essentially nonsliding engagement with the support surface to provide continuous, rigid support. Wheel 40, of course, is free to roll horizontally forwardly toward the vehicle during lifting, but reaction pad 38 will not slip or slide and thereby assures firm footing for the jack.

It will be apparent that the permitted horizontal travel of lift pad 42 relative to support position 32 varies as a function of the horizontal distance between pad 42 and support position 32, or more particularly, as a function of the difference in radial distances between the lift pad 42 and support position 32 from the frame pivotal axis 16. In the preferred form, lift arm 22 is shorter, rather than longer, than support arm 18 so that both ends (pad 42 and wheels 40) of lift frame member 14 travel in the same horizontal direction during lifting. As a result, only the forwardly

disposed frame arms

18 and 22 need to be placed under the vehicle, and the upstanding fluid actuator can be located rearwardly of pivotal axis 16, as shown, in a non-interfering position adjacent and exterior to the vehicle. The shorter lift arm 14 generally accommodates more freedom in all design factors of the jack. For instance, a large, powerfulactuator assembly 26 with a relatively long stroke can be included without worry of interference with the vehicle.

Similar arcuate movement of lift pad 42 relative to support position 32 can be realized by making forward lift arm 22 longer than forward support arm 18, in which case lift pad 42 would move horizontally as before, but in a direction opposite the horizontal motion of wheels 40. Such arrangement requires the jack to be of a design adapting placement of the entire jack asv sembly 10 under the vehicle in a wheels-first manner, to permit lift pad 42 to move horizontally toward the center of the vehicle while wheels 40 roll horizontally away from the vehicle center. This altered design will again furnish limited arcuate motion of the lift pad in general correspondence to the vehicles arcuate lifting path in combination with solid footing for the jack; however, parameters of jack design are more severely restricted (for instance, the frame members could not fold down completely when collapsed) as the entire jack, actuator and a portion of the operating handle must fit under the vehicle undercarriage.

The illustrated embodiment of the invention utilizes a combined form of horizontal travel of support position 32 and horizontal travel of lift pad 42 relative to the support position to generate the desired arcuate lifting motion. This arrangement provides an optimal combination of arcuate lifting motion in keeping with a low profile, compact jack capable of lifting low ground clearance vehicles. lt will be apparent that a greater portion, or all, of the desired lift pad horizontal motion may be generated solely by the horizontal travel of support position 32 or solely by travel of the pad relative to the support position. In particular, horizontal lift. pad travel can be varied either by altering the radius of curvature of the arcuate gripping pad 38 or by changing the distance between lift pad 42 and pivotal axis 16.

The. preferred form illustrated with its shorter lift arm 22 accommodates an extremely low, collapsed profile as shown in FIG. 7 wherein the lift frame member 14 closes completely between the parallel arms 12a and 12b of the reaction support member 12. The improved jack design permits use of a conventional, linear stroke hydraulic actuator that can be disposed horizontally in a low position for storing while still providing a direct vertical raising stroke and additionally, furnishing strong and direct vertical support of the jack and load during raising. The relative arrangements of the various components of the jack assembly further permits incorporation of a simple, easily operated lift pad 42 providing differently formed lifting surfaces, as well as an elongated, multiple-use operating handle capable of folding longitudinally over the jack assembly for storing and carrying. The jack unit thereby presented is quite compact and versatile in nature, and yet sufficiently rugged. and powerful to be amenable for safe, reliable use in conjunction with heavy industrial vehicles having low-ground clearances.

Alterations and variations from the preferred embodiment herein described will be apparent to those skilled: in the art. Accordingly, the foregoing detailed description is to be considered exemplary in nature and not limiting to the scope and spirit of the invention as set forth in the appended claims.

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

l". A jack for raising an object relative to a support surface comprising:

a reaction frame ar-m having a lowermost end adapted to rest at a support position on said support surface;

a lifting frame arm having a contact surface of concavo configurationt at an upper end adapted to engage said object, said reaction and lift arm being pivotally attached to one another in crossing relationship at a frame rotational axis intermediate their ends, said reaction arm lowermost end and lifting arm upper end being located on a forward side of said rotational axis;

a fluid actuator releasably and pivotally attached to said reaction arms in a generally vertical plane located on an opposite rearward side of said frame rotational axis, said actuator being operable to displace said arms vertically from one another and effect raising of the upper ends thereof while said reaction frame arm lowermost end remains in said support position, said actuator being releasable from one of said frame arms to swing to a generally horizontal position for storage;

fluid displacing means carried by said actuator for delivering motive fluid to operate said actuator;

a lever rotatably secured to said actuator;

means telescopically receiving said lever for rotation therewith, said telescoping means being rotatable between a first position operatively engaging said fluid displacing means so as to operate the latter to deliver motive fluid to said actuator, a secondposition extending away from said actuator to facilitate 10 transporting the jack, and'athird, generally horizontal position for storage;

a lift pad carried on said lifting frame arm at said upper end thereof and having a contact surface of convex configuration, said pad being selectively shiftable relative to said lift frame arm to different positions respectively exposing said convex and concavo contact surfaces for lifting engagement with said object, said lift pad being located toposition said exposed contact surface radially closer to said frame pivotal axis than said support position of said lowermost end of the reaction frame arm whereby upon operation of said fluid actuator, said exposed contact surface moves along an arcuate path vertically upwardly and horizontally toward a vertical plane containing said support position of said reaction frame arm lowermost end; and

detent means on said lift arm for operatively engaging said lift pad to lock the latter to said lift arm in said different positions respectively exposing said convex and concavo contact surfaces for lifting engagement with said object.

2. A jack for raising an object relative to a support surface, comprising:

first and second frame members disposed in pivotally interconnected, crossing relationship so that the upper end of each member is positioned adjacent the lowermost end of the other member;

means at the lowermost end of the first member for supporting the jack, said support means being adapted to firmly contact the support surface at a support position thereon in gripping, essentially nonsliding relationship thereto to limit horizontal movement of the jack toward and away from the object; and means at the upper end of the second member adjacent said lowermost end of the first member for firmly contacting the object during relative pivoting of said first and second frame members to effect raising of the upper ends thereof while said support means remains in gripping, nonsliding contact with the support surface, said second member being, disposed on said first member such that the radial distances from said support to said pivotal interconnection are substantially equal for both of said frame members, and said means contacting said object being located radially closer to said pivotal interconnection than said lowermost ends of said frame members, whereby said object engaging means moves horizontally as well as vertically upwardly with the object during said relative pivoting of the first and second members. 3. The device of claim 2 wherein said support means is provided with an arcuate gripping surface of convex configuration for contacting said support surface, said arcuate gripping surface being adapted for predetermined, limited horizontal rolling movement upon said support surface during said relative pivoting of the interconnected first and second frame members.

4. A jack for raising an object relative to a support surface, comprising:

first and second frame members disposed in pivotally interconnected, crossing relationship to rotate in opposite directions about a pivot axis intermediate respective ends thereof, the upper end of said member being positioned adjacent the lowermost end of the other member;

means at the lowermost end of the first member for supporting the jack, said support means being adapted to firmly contact the support surface at a support position thereon in gripping, essentially nonsliding relationship thereto to limit horizontal movement of the jack toward and away from the object;

means at the lowermost end of the second member permitting free horizontal moving contact upon the support surface in response to said relative pivoting; and

means at the upper end of the second member adjacent said lowermost end of the first member for firmly contacting the object during relative pivoting of said first and second frame members to effect raising of the upper ends thereof, said object engaging means being horizontally displaced from said support position in a direction away from the object and being located radially closer to said pivot axis than said support position of the support means to effect travel 1 of said object engaging means and said lowermost end of the second member in the same horizontal direction during said relative pivoting of the first and second frame members.

5. The device of claim 4 wherein said support means is provided with an arcuate gripping surface of convex configuration for contacting said support surface, said arcuate gripping surface being adapted for predetermined, limited, horizontal rolling movement upon said support surface during said relative pivoting of the interconnected first and second frame members, whereby said object engaging means moves horizontally with the object in response to both said arcuate gripping surface rolling movement and said horizontal movment by the object engaging means toward said support position.

6. The device of claim 5 further comprising a transport wheel secured upon said second'frame member at 40 its lowermost end adapted to roll horizontally upon the support surface during said relative pivoting, said transporting wheel having a radius of curvature substantially equal to the radius of curvature of said arcuate gripping surface.

7. The device of claim 6 wherein said first frame member comprises a pair of spaced parallel arms and a plurality of supporting cross members extending transversely across in securing engagement with said parallel arms, said arcuate gripping surface being formed on a cross member located atthe lowermost ends of said parallel arms.

8. The device of claim 7 further comprising a cylin drical mounting pin extending transversely across said parallel arms and being rotatably accepted in a through aperture in said second frame member to form said pivotal axis and pivotally carry said second frame member between said parallel arms of the first frame member.

9. The device of claim 4 further comprising actuating means secured to said first and second frame members and being operable to pivot said frame members in rel- .atively opposite directions between collapsed and operating positions thereof.

10. The device of claim 9 wherein said actuating means include a fluid pressure actuator having a barrel pivotally secured to said first frame member and a rod pivotally secured to said second frame member, said barrel and rod being vertically displaceable from one another to effect said relative pivoting of the first and second frame members.

11. The device of claim 10 wherein said actuating means further include a fluid displacing pump affixed to said barrel and being operatively connected to said fluid actuator to deliver motive fluid thereto to effect said relative pivoting of the first and second frame members.

12. The device of claim 11 further including a manual handle pivotally secured to said barrel and being operatively engageable with said pump to effect deliv ery of motive fluid to said fluid actuator.

13. The device of claim 1 1 wherein said barrel is disposed vertically above said rod and has an exposed upper face, and wherein said fluid actuator further includes pressure control .means for selectively relieving pressure in said fluid pressure actuator to permit return of said first and second frame members from said operating to said collapsed position, said pressure control means being mounted on said barrel upper face for ready accessibility.

14. A foldable lifting jack presenting a low profile in stored condition for ease of storage and carrying comprising:

a frame assembly having elongated, relatively movable lifting members at least one of which is adapted to engage and lift an object during raising thereof, said members being movable into adjacent, parallel, side-by-side relationship for storage and portage;

an elongated actuator permanently and pivotally carried by the frame assembly and operable while in generally vertical disposition to effect raising and lowering of the said one lifting member, said actuator being selectively shiftable to an inoperative location generally parallel and adjacent to the lifting members when the latter are in the storage positions thereof; and

elongated handle means permanently and pivotally coupled to said actuator and selectively movable from an actuator operating position extending away from the latter for operation thereby of the actuator, to a storage location generally proximal to and parallel with the lifting members and said actuator when the latter are all in the storage positions of the same.

15. The jack of claim 14 further comprising a removable locking member adapted to secure said actuator to said frame assembly at a first coupling location thereon when said actuator is in said operating position, said actuator permanently and pivotally secured to said frame assembly at a second coupling location thereon spaced from said first coupling location whereby upon removal of said locking member said actuator is free to pivot about said second coupling location to said inoperative position.

16. The jack of claim 15 wherein said actuator comprises a hydraulic cylinder having a fluid chamber therein and a rod reciprocating relative to the cylinder in response to pressure in said chamber to effect raising and lowering of said one lifting member.

17. The jack of claim 16 wherein said locking member removably secures said reciprocal rod to said one lifting member at said first coupling location and wherein said cylinder is permanently and pivotally secured to another of said frame members at said second coupling location.

18. The jack ofclaim 17 further comprising a positive displacement fluid pump carried with said actuator and interconnected therewith to deliver motive fluid to said cylinder chamber when operated, said handle means being engageable with said fluid pump to manually operate same upon positioning of said handle means in said actuator operating position.

19. The jack of claim 18 wherein said handle means includes a lever pivotally attached to said cylinder and a handle member operatively coupled to said lever to rotate therewith, said handle member being shiftable radially relative to said lever into operating engagement and disengagement with said fluid pump.

20. The jack of claim 1, wherein said lever and handle member are coupled in telescoping arrangement facilitating said handle radial movement.

21. The jack of claim 19 further comprising a first latch on said handle member for positively engaging said fluid pump to permit operation of the latter upon positioning of said handle means in said actuator operating position.

22. The jack of claim 21 further comprising a spring extending between said lever and handle member adapted to bias said handle radially inwardly to operatively engage said first latch with said pump, said handle member being manually shiftable radially outwardly to disengage said first latch from said fluid pump.

23. The jack of claim 22, further comprising a second latch on said handle member for positively engaging said frame assembly, said spring biasing said handle member radially inwardly to operatively engage said second latch with said frame assembly and firmly secure said handle member to said frame assembly upon positioning of said handle means in said storage position, said handle member being manually shiftable outwardly to disengage said second latch from said frame assembly.

.24. Manual operating means for a portable fluid operated lifting jack unit having a fluid actuator and a positive displacement fluid pump carried therewith, said portable unit having transporting wheels and being collapsible to a low, generally horizontal profile for storage, said operating means comprising:

a lever pivotally mounted on said portable unit;

a manually operated handle mounted on said lever for rotation therewith about the pivotal axis of said lever and adapted to slide radially relative to said lever, said handle being selectively rotatable between a generally horizontal storing position in juxtaposed relation to said portable unit when the latter is collapsed for storing,

a transporting position extending away from said portable unit so as to provide an extension facilitating transporting said portable unit on said wheels, and a pumping position engaging said pump to effect operation thereof; and

, locking means on said handle adapted to releasably engage said portable unit at locations spaced radially from said axis of pivoting of the lever upon rotation of the handle to said storing, transporting .and pumping positions, said handle being slidable radially inwardly and outwardly relative to said lever to respectively engage and disengage said locking means with said portable unit, said locking means nonrotatably securing the handle to said portableunit in said storing and transporting positions and rotatably intersecuring said pump and handle in said pumping position to permit operation of said pump upon rotation of said handle.

25. The device of claim 24 wherein said lever includes a radially extending tubular member and wherein said handle includes a tubular member telescopically received by the lever tubular member for limited radial movement relative thereto.

26. The device of claim 25 further including a spring mounted within said tubular members and acting therebetween to bias said handle radially inwardly to engage said locking means with said portable unit.

27. The device of claim 24 wherein said locking means includes a first latch carried by said handle securely engaging said portable unit at a location spaced from said fluid actuator and pump upon positioning the handle in said storing position, and a second latch carried by said handle engaging said fluid actuator in said transporting position and engaging said pump in said pumping position.

28. The device of claim 24 wherein said lever is pivotally mounted on said fluid actuator and wherein said handle extends generally vertically from said actuator when in said transporting position.

29. In a jack having a lifting assembly movable into load bearing engagement with various objects to be lifted, wherein the improvement comprises:

shiftable lifting structure including a lifting member and a lift pad carried by said lifting member and movable relative thereto between first and second positions therein;

means including a load bearing mounting pin on said lifting member for releasably engaging and holding said lift pad in fixed relationship to said lifting member upon positioning of said lift pad in said first position, said mounting pin being received within an enlarged opening provided in said pad to slidably mount the latter on the lifting member, said pin being adapted to transmit loads experienced by said pad to the lifting member;

a first contact surface on said pad exposed to engage the object to be lifted upon positioning of said pad in said first position; and

a second contact surface formed in said lifting structure and exposed to engage the object to be lifted upon positioning of said pad in said second position, the portion of one of the contact surfaces adapted to engage an object being of concave configuration to receive a narrow object lift point therewithin and the portion of the other contact surface adapted to engage .an object being of convex configuration to remain in firm engagement with a broad lift point on an object being lifted during lifting thereof.

30. The improvement of claim 29 wherein said pad holding means comprises a detent formed on said lifting member and engaging said pad to lock same in fixed relationship to said lifting member upon positioning of said pad in said first and second positions.

31. The improvement of claim 29 wherein said second contact surface is formed on said lifting member.

32. The improvement of claim 31 wherein said first contact surface is of convex configuration and said second contact surface is of concave configuration, said convex first contact surface being exposed and lying over said concave second contact surface upon positioning of said pad in said first position.

33. The improvement of claim 32 wherein said convex first contact surface has a plurality of parallel grooves facilitating gripping said broad lift point on an object being lifted.

34. A jack for raising an object relative to a support surface, comprising:

first and second frame members disposed in pivotally interconnected, crossing relationship operable to rotate in opposite directions about a pivot axis intermediate their ends, the upper end of each member being positioned adjacent the lowermost end of the other member;

means at the lowermost end of the first member for supporting the jack, said support means being provided with an arcuate gripping surface of convex configuration for contacting said support surface and being adapted for predetermined, limited horizontal rolling movement upon said support surface during said pivoting of the interconnected first and second frame members;

means at the lowermost end of the second member being adapted for free horizontal moving contact upon the support surface in response to said relative pivoting, the radial distance from said pivot axis to said support surface for each of said frame members being substantially equal; and

means at the upper end of the second member adjacent the lowermost end of the first member for firmly contacting the object during pivoting of said first and second frame members to effect raising of the upper ends thereof, the radial distance from said pivot axis to said contact means being substantially shorter than the radial distances of said frame members from said pivot axis to said support surface, to thereby move said contact means horizontally toward said object as well as vertically upwardly with the object during said relative pivoting of the first and second members.

Claims

1. A jack for raising an object relative to a support surface comprising: a reaction frame arm having a lowermost end adapted to rest at a support position on said support surface; a lifting frame arm having a contact surface of concavo configuration at an upper end adapted to engage said object, said reaction and lift arm being pivotally attached to one another in crossing relationship at a frame rotational axis intermediate their ends, said reaction arm lowermost end and lifting arm upper end being located on a forward side of said rotational axis; a fluid actuator releasably and pivotally attached to said reaction arms in a generally vertical plane located on an opposite rearward side of said frame rotational axis, said actuator being operable to diSplace said arms vertically from one another and effect raising of the upper ends thereof while said reaction frame arm lowermost end remains in said support position, said actuator being releasable from one of said frame arms to swing to a generally horizontal position for storage; fluid displacing means carried by said actuator for delivering motive fluid to operate said actuator; a lever rotatably secured to said actuator; means telescopically receiving said lever for rotation therewith, said telescoping means being rotatable between a first position operatively engaging said fluid displacing means so as to operate the latter to deliver motive fluid to said actuator, a second position extending away from said actuator to facilitate transporting the jack, and a third, generally horizontal position for storage; a lift pad carried on said lifting frame arm at said upper end thereof and having a contact surface of convex configuration, said pad being selectively shiftable relative to said lift frame arm to different positions respectively exposing said convex and concavo contact surfaces for lifting engagement with said object, said lift pad being located to position said exposed contact surface radially closer to said frame pivotal axis than said support position of said lowermost end of the reaction frame arm whereby upon operation of said fluid actuator, said exposed contact surface moves along an arcuate path vertically upwardly and horizontally toward a vertical plane containing said support position of said reaction frame arm lowermost end; and detent means on said lift arm for operatively engaging said lift pad to lock the latter to said lift arm in said different positions respectively exposing said convex and concavo contact surfaces for lifting engagement with said object.

2. A jack for raising an object relative to a support surface, comprising: first and second frame members disposed in pivotally interconnected, crossing relationship so that the upper end of each member is positioned adjacent the lowermost end of the other member; means at the lowermost end of the first member for supporting the jack, said support means being adapted to firmly contact the support surface at a support position thereon in gripping, essentially nonsliding relationship thereto to limit horizontal movement of the jack toward and away from the object; and means at the upper end of the second member adjacent said lowermost end of the first member for firmly contacting the object during relative pivoting of said first and second frame members to effect raising of the upper ends thereof while said support means remains in gripping, nonsliding contact with the support surface, said second member being disposed on said first member such that the radial distances from said support to said pivotal interconnection are substantially equal for both of said frame members, and said means contacting said object being located radially closer to said pivotal interconnection than said lowermost ends of said frame members, whereby said object engaging means moves horizontally as well as vertically upwardly with the object during said relative pivoting of the first and second members.

3. The device of claim 2 wherein said support means is provided with an arcuate gripping surface of convex configuration for contacting said support surface, said arcuate gripping surface being adapted for predetermined, limited horizontal rolling movement upon said support surface during said relative pivoting of the interconnected first and second frame members.

4. A jack for raising an object relative to a support surface, comprising: first and second frame members disposed in pivotally interconnected, crossing relationship to rotate in opposite directions about a pivot axis intermediate respective ends thereof, the upper end of said member being positioned adjacent the lowermost end of the other member; means at the lowermost end of the first member for supportiNg the jack, said support means being adapted to firmly contact the support surface at a support position thereon in gripping, essentially nonsliding relationship thereto to limit horizontal movement of the jack toward and away from the object; means at the lowermost end of the second member permitting free horizontal moving contact upon the support surface in response to said relative pivoting; and means at the upper end of the second member adjacent said lowermost end of the first member for firmly contacting the object during relative pivoting of said first and second frame members to effect raising of the upper ends thereof, said object engaging means being horizontally displaced from said support position in a direction away from the object and being located radially closer to said pivot axis than said support position of the support means to effect travel of said object engaging means and said lowermost end of the second member in the same horizontal direction during said relative pivoting of the first and second frame members.

6. The device of claim 5 further comprising a transport wheel secured upon said second frame member at its lowermost end adapted to roll horizontally upon the support surface during said relative pivoting, said transporting wheel having a radius of curvature substantially equal to the radius of curvature of said arcuate gripping surface.

7. The device of claim 6 wherein said first frame member comprises a pair of spaced parallel arms and a plurality of supporting cross members extending transversely across in securing engagement with said parallel arms, said arcuate gripping surface being formed on a cross member located at the lowermost ends of said parallel arms.

8. The device of claim 7 further comprising a cylindrical mounting pin extending transversely across said parallel arms and being rotatably accepted in a through aperture in said second frame member to form said pivotal axis and pivotally carry said second frame member between said parallel arms of the first frame member.

9. The device of claim 4 further comprising actuating means secured to said first and second frame members and being operable to pivot said frame members in relatively opposite directions between collapsed and operating positions thereof.

12. The device of claim 11 further including a manual handle pivotally secured to said barrel and being operatively engageable with said pump to effect delivery of motive fluid to said fluid actuator.

13. The device of claim 11 wherein said barrel is disposed vertically above said rod and has an exposed upper face, and wherein said fluid actuator further includes pressure control means for selectively relieving pressure in said fluid pressure actuator to permit return of said first and second frame membeRs from said operating to said collapsed position, said pressure control means being mounted on said barrel upper face for ready accessibility.

14. A foldable lifting jack presenting a low profile in stored condition for ease of storage and carrying comprising: a frame assembly having elongated, relatively movable lifting members at least one of which is adapted to engage and lift an object during raising thereof, said members being movable into adjacent, parallel, side-by-side relationship for storage and portage; an elongated actuator permanently and pivotally carried by the frame assembly and operable while in generally vertical disposition to effect raising and lowering of the said one lifting member, said actuator being selectively shiftable to an inoperative location generally parallel and adjacent to the lifting members when the latter are in the storage positions thereof; and elongated handle means permanently and pivotally coupled to said actuator and selectively movable from an actuator operating position extending away from the latter for operation thereby of the actuator, to a storage location generally proximal to and parallel with the lifting members and said actuator when the latter are all in the storage positions of the same.

18. The jack of claim 17 further comprising a positive displacement fluid pump carried with said actuator and interconnected therewith to deliver motive fluid to said cylinder chamber when operated, said handle means being engageable with said fluid pump to manually operate same upon positioning of said handle means in said actuator operating position.

24. Manual operating means for a portable fluid operated lifting jack unit having a fluid actuator and a positive displacement fluid pump carried therewith, said portable unit having transporting wheels and being collapsible to a low, generally horizontal profile for storage, said operating means comprising: a lever pivotally mounted on said portable unit; a manually operated handle mounted on said lever for rotation therewith about the pivotal axis of said lever and adapted to slide radially relative to said lever, said handle being selectively rotatable between a generally horizontal storing position in juxtaposed relation to said portable unit when the latter is collapsed for storing, a transporting position extending away from said portable unit so as to provide an extension facilitating transporting said portable unit on said wheels, and a pumping position engaging said pump to effect operation thereof; and locking means on said handle adapted to releasably engage said portable unit at locations spaced radially from said axis of pivoting of the lever upon rotation of the handle to said storing, transporting and pumping positions, said handle being slidable radially inwardly and outwardly relative to said lever to respectively engage and disengage said locking means with said portable unit, said locking means nonrotatably securing the handle to said portable unit in said storing and transporting positions and rotatably intersecuring said pump and handle in said pumping position to permit operation of said pump upon rotation of said handle.

29. In a jack having a lifting assembly movable into load bearing engagement with various objects to be lifted, wherein the improvement comprises: shiftable lifting structure including a lifting member and a lift pad carried by said lifting member and movable relative thereto between first and second positions therein; means including a load bearing mounting pin on said lifting member for releasably engaging and holding said lift pad in fixed relationship to said lifting member upon positioning of said lift pad in said first position, said mounting pin being received within an enlarged opening provided in said pad to slidably mount the latter on the lifting member, said pin being adapted to transmit loads experienced by said pad to the lifting member; a first contact surface on said pad exposed to engage the object to be lifted upon positioning of said pad in said first position; and a second contact surface formed in said lifting structure and exposed to engage the object to be lifted upon positioning of said pad in said second position, the portion of one of the contact surfaces adapted to engage an object being of concave configuration to receive a narrow object lift point therewithin and the portion of the other contact sUrface adapted to engage an object being of convex configuration to remain in firm engagement with a broad lift point on an object being lifted during lifting thereof.

34. A jack for raising an object relative to a support surface, comprising: first and second frame members disposed in pivotally interconnected, crossing relationship operable to rotate in opposite directions about a pivot axis intermediate their ends, the upper end of each member being positioned adjacent the lowermost end of the other member; means at the lowermost end of the first member for supporting the jack, said support means being provided with an arcuate gripping surface of convex configuration for contacting said support surface and being adapted for predetermined, limited horizontal rolling movement upon said support surface during said pivoting of the interconnected first and second frame members; means at the lowermost end of the second member being adapted for free horizontal moving contact upon the support surface in response to said relative pivoting, the radial distance from said pivot axis to said support surface for each of said frame members being substantially equal; and means at the upper end of the second member adjacent the lowermost end of the first member for firmly contacting the object during pivoting of said first and second frame members to effect raising of the upper ends thereof, the radial distance from said pivot axis to said contact means being substantially shorter than the radial distances of said frame members from said pivot axis to said support surface, to thereby move said contact means horizontally toward said object as well as vertically upwardly with the object during said relative pivoting of the first and second members.