US2730903A

US2730903A - Lifting jack

Info

Publication number: US2730903A
Application number: US302673A
Authority: US
Inventors: Walter C Trautman; Lyle L Arnes
Original assignee: WALKER Manufacturing Co OF WISCOUSI
Current assignee: WALKER Manufacturing Co OF WISCOUSI; WALKER MANUFACTURING Co OF WISCOUSIN
Priority date: 1952-08-05
Filing date: 1952-08-05
Publication date: 1956-01-17
Anticipated expiration: 1973-01-17

Description

Jan. 17., 1956 W. C. TRAUTMAN I'AL LIFTING JACK Filed Aug. 5, 1952 2 Sheets-Sheet l gill-11E- IN VEN TOR.

Jan. 17, 1956 w. c. TRAUTMAN ErAL 2,730,903

LIFTING JACK Ow Filed Aug. 5, 1952 2 Sheets-Sheet 2 United States Patent O LIFTIN G JACK Walter C. Trautman and Lyle L. Ames, Racine, Wis., assignors to Walker Manufacturing Company of Wisconsin, Racine, Wis., a corporation of Wisconsin Application August 5, 1952, Serial No. 302,673

14 Claims. (Cl. 74--141.5)

This invention relates to lifting jacks, and more particularly to pawl and ratchet type lifting jacks adapted for use as bumper jacks for vehicles and in similar applications.

It is an object to provide a novel and improved type of pawl and ratchet lifting jack, in which the holding and lifting pawls are connected by a single coil helical spring, instead of the conventional iiat or leaf spring, thus providing a construction which is cheaper to construct, more eiiicient in operation, and which increases the allowable tolerances of manufacture.

lt is another object to provide an improved lifting jack of the above nature, which utilizes a single coil helical spring in transverse bending, tension and compression, so that the coil spring can function both to urge the pawls toward the rack bar and to carry the pawls away from the bar.

It is a further object to provide a novel and improved lifting jack of the above nature, having a simple lever for shifting the jack between its raising and lowering settings, this lever working in a slot and having means for preventing accidental engagement of one of the spring anchor pins in said slot.

Other objects, features, and advantages of the present invention will become apparent from the subsequent description, taken in conjunction with the accompanying drawings.

ln the drawings:

Figure l is a side elevational View of a jack embodying the principles of this invention;

Figure 2 is a fragmentary rear elevational view of the pawls, spring and setting lever;

Figure 3 is a detailed view of the setting lever, showing the guard lip;

Figure 4 is a fragmentary side elevational view showing the operation of the pawls with the setting lever in raising position and the handle socket in its lower position;

Figure 5 is a view similar to Figure 4 but with the handle socket in raised position;

Figure 6 is a view similar to Figures 4 and 5 but with the setting lever in the lowering position and the handle socket in its lower position;

Figure 7 is a view similar to Figure 6 but with the handle socket in partially raised position; and

Figure 8 is a view similar to Figures 6 and 7 but with the handle socket in fully raised position.

The jack comprises in general a base 11 and a rack bar 12 fixed to the base and extending upwardly therefrom. The rack bar has a plurality of ratchet teeth 13 along one edge thereof, these teeth having upwardly facing engaging surfaces 14 normal to the rack bar axis. The body portion of the jack is shown in the present embodiment as comprising two halves, generally indicated at 15 and 16 and fabricated of pressed metal. It wl be understood, of course, that the body of the jack could be constructed in other ways. Each body half 15 and 2,730,903 Patented Jan. 17, 1956 ICC " portions cooperating to form a rectangular rack bar receiving portion 17. Outwardly extending

lips

18 and 19 at the upper and lower ends of the body halves are secured together and serve to connect the halves as an integral unit. The body halves are each also provided with a load engaging extension 21, these extensions also being joined and serving to unite the body halves.

The

body halves

15 and 16 have rearwardly extending

portions

22 and 23 respectively in spaced. parallel relation, and between the upper portions of these relatively flat extensions is a handle socket 24 supported by a pivot pin 25. The handle socket is formed inthe illustrated embodiment with two spaced-apart locating portions 26 which engage the inner surfaces of

extensions

22 and 23 to prevent lateral movement of the socket. Pivot pin 25 also pivotally supports a holding pawl 27 which has a toe 28 at its lower end engageable with rack teeth 13. Pivotally supported at 29 between portions 26 of the handle socket is a lifting pawl 3l. This lifting pawl is substantially longer than holding pawl 27 and is shown as of somewhat arcuate shape, having a toe 32 adapted to engage teeth 13. It will be noted that because of the curved nature of pawl 31 and the rearward spacing of pin 29 from pin 25, the holding and lifting pawls are in non-interfering relationship, although they are in substantially the same plane.

Extensions

22 and 23 of the

housing halves

15 and 16 substantially enclose holding pawl 27 and lifting pawl 31, the thickness of these pawls being substantially less than the spacing between

extensions

22 and 23. Extension 22 has an upraised portion 33 which is outwardly spaced from the longitudinal centerline of the jack, and this upraised portion accommodates a single coil helical spring 34 which is disposed in the space between

pawls

27 and 31 and extension 22. Helical spring 34 is counected at one end 35 to holding pawl 27 by means of a pin 36 secured to the side of the lower end of said pawl, and the other end 37 of spring 34 is connected to lifting pawl 3l by means of pin 38 extending from its lower portion. Spring 34 is of the type which when in its unstressed condition has open turns, so that the Ispring may be placed under compressive load without buckling, at least for a substantial distance until the turns are forced together. Moreover, ends 35 and 37 of the spring are connected to

pins

36 and 38 respectively in such a manner that the spring may be `subjected to compressive loading by relative approaching movement of

pins

36 and 38.

Means are provided for setting the pawls and spring 34 in either a lifting or a lowering position, and this means comprises in the illustrated embodiment a setting lever 39 mounted on upraised portion 33 of extension 22. In particular, upraised portion 33 is provided with an L- shaped slot having a lower portion 41 and an upper portion 42. Portion 41 of the slot slants downwardly and rearwardly, and could be considered forl purposes of description as approximately parallel to the axis of spring 34 when the latter is not engaged by lever 39, as described below. Upper portion 42 of the slot is substantially at right angles to lower portion 41, and extends downwardly and forwardly toward the spring. Lever 39 is shown in the present embodiment as being formed of a doubled or bent back metal strap, carrying a guide pin 43. Lever 39 is tted over the rear edge of upraised portion 33, the shorter side 44 of the lever being on the side facing the pawls, and the long side 45 on the outside of the upper edge portion. The outer end 46 of side 45 of the lever is narrowed, and a spring engaging toe 47 extends laterally from this narrow portion through slot 42. This toe is preferably of somewhat arcuate crosssection, and is slightly wider than the width of slot portion 42, thus retaining the lever in position.

The juncture of slot portions 41 and 42 is provided with lowering positions.

av'recess `48'which serves as a detent to retain guide pin 43`v`vhen the lever 39 is in the position shown in Figures 4 and'S. It will be noted that' when in this position, the distance betweenpin-,43 andtoe 47 is such that the toe exerts aftransver's'e'bending force on an intermediate portion of'spring 3,4, urging Vthe spring toward the rack bar.l

Thel lever 39`may`be moved into its lower position shown in Figures-6,V 7 and 8 by'pushing the lever downwardly so that pinf 43 enters slot portion 41, the detent action of recess 448 being slight enough to release the pin when forced downwardly. When in this position, it will be seen that toe 47 is entirelyfree of spring 34. In order to move lever 39 from its lower to its upper position, it is merely necessaryto-lift the lever ina counterclockwise direction, upon which pin 43'lwill slide up along slot portion 41 until it snaps into place in recess 48.

VIn order to prevent the accidental entry of pin 33 in slot portions 41 and 42, which would of course impair the operation of the jack, the shorter side 44 of lever 39 is provided ,with Ian extension 49 which covers the slot 41-42 suilicientlyl to prevent. pin 33 from entering the slot.

The operationof the jack is-best described with relation to Figures 4 land y5, which show the sequential positions in raising, and Figures 6, 7 and 8 which show the sequential The lever 39 is in its raised position engaging spring 34 when it is desired to raise the jack, and' when lowering is desired the lever is in its lower position. Basically, the difference in raising and lowering operations stemsfrom the function of spring 34, which when engaged by lever 39 is always under tension caused by thejtransverse bending force on its intermediate portion, but which when released by lever 39 acts alternately as a tension spring and as a pivoted link subject to cornpression.

In ,-the raising operation, the tension caused by the transversevbendingforce applied to spring 3d by lever 39 is such that both holding pawl' 27 and lifting pawl 3l are constantly held against the rack bar teeth. Starting from a-positionin which the socket handle is lowered, as shown in Figure A4,y the lifting pawl 31 will engage one of the teeth13 of the rack bar. Lowering of the handle socket, which pivots about pin 29 when pawl 31 engages the rack bar, will cause lifting of pin 25, with subsequent raising of thel housing and of holding pau/127. When the holding pawlpasses over the apex of the next upper tooth 13, spring 34.wi11 cause it to snap into place above the engaging surface 14 thereof. Subsequent lifting of handle socket 24, as shown in lFigure will cause the handle socket to pivot'about `pin 25, raising pin 29. Lifting pawl 3l wili thusbe'carried upwardly over the apex of the next upper tooth`13, and willjbe snapped into position above the surface 14-of this tooth by spring 34. lt should be noted at this"` point that the raising of handle socket 2d places spring 34 under, even greater tension and bending stresses than existed when the handle socket was in its iower position, and the spring is preferably so constructed that this bending action will-not place a permanent set in the turns. It will be seen that repeated raising and lowering of the handle Vsocket will therefore cause holding and lifting pawls 2,7 and 31 to advance intermittently on the rack bar. The fact that spring 34 continually urges both pawls toward the rack bar prevents any accidental removal of the pawls from the rack bar to release the jack.

When it visvdesired to lower the jack, lever 39 is rotated into its lower position as shown in Figures 6, 7 and 8. In the position Vshown in Figure 6, the handle socket is in its lowermost position and is about to be raised. Lifting pawl y31 is 'engaging the rack bar and holding pawl 2'7 is clear of the rack bar teeth. The holding pawl has just beenpulled away from the rack bar teeth by spring 34, which is now unstressed. Upon moving the handle socket 'counterclockwise,` the socket will pivot about pivo-t pin 2 9, so that the yjackbody as welles holding pawl 27 will belowered. 'The holdingpawljwill pass the'apex of the tooth from which it has just been released, and the mutual Vapproach of springsupporting pins 36 and 38 will evenreleased, and will slide down this tooth until it abuts the engaging face 14 ofthe next succeeding lower tooth. During this period of engagement of pawl 27 and rack bar, spring 34 undergoes compression due to the relative approach of anchor pins 36 and 38 so that whenlthe handle socket reaches the position shown in Figure 7, the spring is tending to push lifting pawl 31 outwardly away from the rack bar. Upon lfurther lifting of the handle socket to the position shown in 'Figure 8, the holding pawl 27 will assume the load,'and lifting pawl 31 will be lifted away from its tooth and will be forced away from the rack bar by spring 34. The spring is now again acting as a link, since it Vis'n'either under tension nor compression, and when the handle socket is lowered from the position shown in Figure 8, lifting pawl 3l will be held away from Y the rack bar by spring 34 until its toe 32 engages the next lower succeeding tooth.V During this movemenn'pius 36 and 3S are again being separated, so that by the time pawl 3l. engages its'next tooth, spring 3d is under tension. Subsequent lowering of the handle socket to the position shown in Figure 6, will thus release pawl Z7 from the rack bar and permit spring 34 to pull the holding pawl away from the rack bar. The cycle will thenV be repeated.

While it will be apparent that the preferred embodiment of the invention herein disclosed is well Vcalculatedto fulfill the objects above stated, it will be appreciated that the invention is susceptible to modification, variation and change without departing from the proper scope or fair meaning of the subjoined claims. v

What is claimed is:

l. ln a lifting jack, the combination of a bodyfmem.- ber and an actuating member pivoted to the body mem- .V ber, a holdingpawl pivoted to one of said members, a

lifting pawl pivoted to said actuating member, a vsingle coil helical spring forming a permanent link between said pawls and energizing operating movement of the pawls toward and away from each other, a fixed pivotal connection between one end of said spring and said holding pawl, and a fixed pivotal connection between the other end of said spring and said lifting pawl.

2. ln a lifting jack, a rack bar, a body member slidable thereon, an actuating member pivoted to the said body member, Va holding pawl pivoted to one of said members, a lifting pawl pivoted to said actuating member, a single coil helical spring forming a permanent linkbe-V tween said pawls and'energizing operating movement of said pawls toward'and away from said rack bar, a fixed pivotal connection between one end of said spring and said holding pawl, and a xedpivotal connection between the other end of said spring andsaid lifting pawl.

3. ln a lifting jack, the combination of a body member and an actuating member pivoted to said body member, a holding pawl pivoted to one of said members, a

' lifting pawl pivoted to said actuating member, a helical spring forming a permanent link between said pawls, and a setting member' movable between a iirst position in engagement with an intermediate portion of said spring and a second position away from said spring.

4. In a lifting jack, a rack bar, a body member slidable thereon, an actuating member pivoted to said body member, a holding pawl pivoted to one of said members, a. lifting pawl pivoted to said actuating member, a helical spring formingY a permanent link between said pawls, and a setting member movable between a first position in engagement with an intermediate portion of said spring so as to urge said pawls toward said rack bar, and a second position away from said spring.

5. In a lifting jack, a rack bar, a body member slidable thereon, an actuating member pivoted to said body member, a holding pawl pivoted to one of said members, a lifting pawl pivoted to said actuating member, a helical spring forming a permanent link between said pawls, and a setting member movable between a first position in engagement with an intermediate portion of said helical spring so as to urge said pawls toward said rack bar, and a second position away from said spring, said spring having open turns when in an unstressed condition, whereby relative approach of said pawls will tend to compress said spring when said setting member is in its second position.

6. In a lifting jack, the combination of a body member and an actuating member, means for pivoting said actuating member to said body member, a holding pawl pivoted to said body member, a lifting pawl pivoted to said actuating member, a single coil helical spring forming a permanent link between said pawls and energizing operating movement of the pawls toward and away from each other, a fixed pivotal connection between one end of said spring and said holding pawl, and a fixed pivotal connection between the other end of said spring and said lifting pawl.

7. In a lifting jack, a rack bar, a body member slidable on said rack bar, an actuating member, means for pivoting said actuating member to said body member, a holding pawl pivotally supported by said body member, a lifting pawl pivoted to said actuating member, a helical spring forming a permanent link between said holding and lifting pawls at points spaced from their respective pivot axes, and a setting member movable between a jack raising position in engagement with an intermediate portion of said spring to urge said pawls toward said rack bar, and a jack-lowering position away from said spring.

8. In a lifting jack, a rack bar, a jack housing slidable thereon, rearward extensions in spaced parallel relation on said jack housing, an actuating member pivotally secured between said extensions, a holding pawl pivoted to said body member, a lifting pawl pivoted to said actuating member, a setting member, a helical spring forming a permanent connection between said pawls, and a slotted portion on one of said jack body extensions for supporting said setting member, the setting member being movable in said slotted portion between a first position in engagement with an intermediate portion of said spring, and a second position away from said spring.

9. In a lifting jack, a rack bar, a jack housing slidable thereon, rearward extensions in spaced parallel relation on said jack housing, an actuating member pivotally secured between said extensions, a holding pawl supported by said pivotal means, a lifting pawl pivoted to said actuating member, a helical spring interconnecting said pawls, a setting member, a slotted portion in one of said extensions, a pin carried by said setting member and extending through said slotted portion, said setting member being movable between a first position engaging said spring and urging said pawls toward said rack bar, and a second position away from said spring, and detent means forming part of said slotted portion for retaining said setting member in its first position.

10. In a lifting jack, a rack bar, a jack housing slidable thereon, rearward extensions in spaced parallel relation on said jack housing, an actuating member pivotally secured between said extensions, a holding pawl supported by said pivotal means, a lifting pawl pivoted to said actuating member, a helical spring, anchor means on said pawls for securing said spring therebetween, at

Cil

least one of said anchor means comprising a pin, a setting member, said setting member being movable between a first position engaging said spring and urging said pawls toward said rack bar, and a second position away from said spring, said setting member having spaced apart parallel portions tting over one of said extensions, a pin carried between said parallel portions, a slotted portion in said one extension, said pin being disposed in said slotted portion, a lateral toe on one portion of said setting member engageable with said spring when the setting member is in its first position, and a guard extension on the other portion of said setting member partially covering said slotted portion, whereby said anchor pin is prevented from entering said slotted portion.

ll. In a lifting jack, the combination of a body member and an actuating member having extensions in spaced parallel relation pivoted to said body member, a holding pawl pivoted to one `of said members, a lifting pawl pivoted to said actuating member, a helical spring interconnecting said pawls, a setting member, a slotted portion in one of said extensions, a pin carried by said setting member and extending through said slotted portion, said setting member being movable between a first position engaging said spring and urging said pawls toward said rack bar, and a second position away from said spring, and detent means forming part of said slotted portion for retaining said setting member in its first position by engagement with said pin.

12. In a lifting jack, a rack bar, a body member slidable thereon, an actuating member pivoted to said body member, a holding pawl pivoted to said body member, a lifting pawl pivoted to said actuating member, a helical spring forming a permanent link betwen said pawls, and a setting member movable between a first position in engagement with and exerting a transverse bending force on an intermediate portion of said spring so as to urge said pawls toward said rack bar, and a second position away from said spring.

13. In a lifting jack, a rack bar, a body member slidable on said rack bar, an actuating member, means for pivoting said actuating member to said body member, a holding pawl pivotally supported by said body member, a lifting pawl pivoted on said actuating member, a helical spring forming a permanent link between said holding and lifting pawls at points spaced from their respective pivot axes, and a setting member movable between a jack raising position in engagement with and exerting a transverse bending force on an intermediate portion of said spring to urge said pawls toward said rack bar, and a jack lowering position away from said spring.

14. In a lifting jack, a rack bar, a body member slidable thereon, an actuating member pivoted to said body member, a holding pawl pivoted to said body member, a lifting pawl pivoted to said actuating member, a single coil helical spring forming a permanent link between said pawls and energizing operating movement of the pawls toward and away from each other, a fixed pivotal connection between one end of said spring and said holding pawl, a fixed pivotal connection between the other end of said spring and said lifting pawl, and a setting member movable between a first position in engagement with an intermediate portion of said spring and a second position away from said spring.

References Cited inthe file of this patent UNITED STATES PATE-NTS 1,093,269 I-Iindman April 14, 1914 1,771,221 Johnson July 22, 1930 1,829,656 Johnson Oct. 27, 1931 1,839,528 Benoit Jan. 5, 1932 2,463,772 Hunz Mar. 8, 1949