US1821231A - Planetary operating mechanism for lifting jacks - Google Patents

Description

L. D. NILSON sept, 1', 1931.?

PLANETARY OPERATING MECHANIS'M FOR LIFTING JACKS Filed ct. 2v. 1927 '5 sheets-Sheet 1- @Mr/ame* f Spt. l, 1931. L. D. NlLsoN 1,821,231

PLANETARY OPERATING MECHANISM OR LIFTING JACKS4 Filed oct. 27, 1927` 5 sheets-meet 2 Sept. ,1, 1931*.'` p. NlLsoN 1,821,231

PLANETARY OPERATING MECHANISM FOR LIFTING JACKS v Filed oct. 27, 1927 5 sheets-sheet s l.. D. N'lLlsoN sept. 1,1931.

PLANETARY OPERATING MECHANISM FOR LIFTING JAGKS 5 Sheets-Sheet 4 I Filed Oct. 27, 1927 Jule/M02?, A'Iren/mm 9217x022w L. D. NILSON Sept. l, 1931.

PLANETARY OPERATING MECHANISM FOR LIFTING JACKS Filed Oct. 27, 1927 5 Sheets-Sheet 5 atented Sept. l, 193i LEONARD D. NILSON, F WAYZATA, MXNNESGTB PLANETARY OPEBATENG ll'IECHAIllShI FOR LIFTi'C-f JACKS Application .led October 27, 192?. Serial No. 229,11*?.

`o object` of my invention is to provide ting jack having a lifting arm pivoted at a high point of the frame of the jack but havimr e lil g se Ajing end thereof adapted to be poiftioned relatively low when in lowered position and adapted yto be relatively high when in raised position whereby it is especia ily adapted fornse on automobiles having balloon tires .10 A further object of my invention is to virovide actuating means for the lifting arm in the forni of planetary gearing inechenie'n whereby considerable leverage is obtained 'tor raising ythe li tin@ arm.

Still a further object is to provide in a jack of this character a long low frame having lifting mechanism on one end thereof which can be conveniently wheeled into position beneatnv the axle of an automobile or @e he like when the tire thereon is fiat .for

the purpose of raising snch axle.

Another important object of my invention to arrange the lifting arm to extend downwardly at an angle when in lowered position and to extend upwardly at an angle i in raised position, the lifting arm being pivoted for sv. inging movement from one of these positions to the other whereby the lifting arm when in intermediate position is substantially level.

From t foregoing object it will be obvious that more leverage will be had adjacent lowered and raised positions of the hiring arm and less leverage. at the intermediate position whereby more power is ro- '.niired at such intermediate position and it is therefore a further object of my invention 'to iii-ov which has a greater leverage at the inten mediate position than it does adjacent the lowered and raised positions thereof 'the of counteracting the variation in caused by the swinging of the actuating means for the lifting arm provide a pair of curved rack bars on .the frame of the jacl ainl a pair of pinions jonrnaied on the lifting arm and a ratchet wheel associated witn the pinions whereby Y rotation may be imparted to the ratchet wheel forrotating the pinions, an operative connection being established between the pinions and the rack bars by intermediate pnnons.

Still another object of my invention `is F5 'to 1provide means for actnating'the ratchet wheel, said means being pivoted at the rear end of the Vjack frame and adapted upon oscillation to canse movement of a lifting pawl which is associated with the ratchet W wheel whereby rotation vmay be imparted to the mechanism for swinging the lifting arm.

Still a further object is to provide the oscillating means at the rear end of the jack frame in three parts, a notched sector, arlever and a handle, the lever being -provided with a sliding dog to coact selectively with the notches of the sector.

till a further object is to pivot the handle 7 to the lever whereby the handle may be moved to a supine position resting on top of the -iaclr frame so that the device, in effect, is folded for the purpose of transportation. p i

Still a further object is to provide a latching lever on the handle and a link connection with the dog or latch member, the connection of the linlr to the latch member coinciding with the pivotal connection of the handle to the lever whereby movement $3" of the handle to a supine position does not ar'iect or bend the latching mechanism.

Still a. further object of my present invention is to provide a modified formof lifting jack having a gear and 'pinion operating connection between a pawl actuated ratchet wheel and a curved rack bar whereby the speed of the lifting arm relative to the speed of the ratchet wheel is considerably reduced Y which results in va jack especially adapted "9 les to raise a comparatively heavy load such as a truck.

wWith these and other objects in view7 my invention consists in the construction, arrangement and combination of the various parts of my planetary operating mechanism for lifting jacks wher-e y the objects contemplated are attained, as hereinafter more fully set forth, pointed out in my claims7 and illustrated in the accompanying drawings, in which:

Figure l is a side elevation of a aci; provided with my iiniiroved planetary operating mechanism and showing the li ing head in raised position and the operating handle in dotted lines assuming a supine position, as when the jack is folded for transportation.

Figure 2 is rear end i the jack as viewed from the indicated line 2-2 of Figure l.

Figure 3 is an enlaroed detail sectional view of a locking` mechanism for the operating handle of th fasi and is taken on the line 3 3 of Figure l.

Figure l is an enlarged plan view of the front end of the jack showing the lifting head in lowered position parts being shown in section.

Figures 5, 6, and '.1' arl views taken ou the lines o--r c-o respectively of Figure el.

Figures 8 and 9 are vertical detail sectional views taken on tle lines Sie-8 and 9-9 respectively of Figure 7.

Figure l0 is a sectional view of the ratchet operating mechanism of my iaclr illustrating the reversing mechanism for the lifting and locking pawls in operative position, this ligure illustratiingl the reversing mechanism operating to release the holding pawl from the ratchet wheel.

Figure ll is a view similar to Figure l0 illustrating the reversinrf' mechanism with the lifting pawl moved to position where it is not ai'fected by the reversing mechanism and is free to engage the ratchet wheel.

Figure l2 is a view similar to Figure l0 illustrating the lifting pawl rotating the ratchet wheel whereby the locking pawl is :'ree to be released from the ratchet v b y the reversing mechanism.

Figure 13 is a View similar to Figure l0 .illustrating the lifting oawl allowing the load on the jack to rotate sectional and i1-7 heel the ratchet wheel whereby the lifting pawl engages the versing mechanism, removing it from contact with the locking pawl wherehv the loching` pawl is free to engage the ratchet wheel7 the pawls being illustrated in dotted line position as when the load is released from the lifting arm.

Figure le; is a diagrammatical view of my jack illustrating tne action of it whereby the objects contemplated are attained.

an enlarged plan view of tl e .end of the side frame members l0.

Figure l5 is a vertical sectional view similar to Figure 5 and illustrating a modified form of operative connection whereby a greater speed reduction is had between tlr operating handle of the jack and the load lifting head thereof; and

Figure 1G is a detail sectional view taken on the line l6-l6 of Figure l5.

@n the accompanying drawings I have used. the reference numeral 1() to indicate the side frame members of my jack. The members l0 may be formed of channel bars or some suitable material and are made in pairs for forming a box-like frame construction. Secured to the forward end of each frame member 1U is a side frame casting l2. best illustrated in Figure 5 of the drawings. 'lho castings 12 may he secured by bolts l-l to the side members l0 and by a boltl 1G spaced from the bolts lil. rlhe bolts 14 each entend through one of the castings l2 and one of the members l() while the bolt 1G extends through both'members l0 and both castings l2. il. spacing sleeve 18 is positioned on the bolt 16 between the castings l2 for holding the frame members l() in proper spaced position with relation to each other and for forming a rigid frame Work of the parts :ist described.

not r bolt 2() extends through ears 22 formed on the upper edges of the castings l2 in a manner similar to the bolt 16. il. spacing sleeve 24.'- is provided on the bolt 2() and entends between the ears 22. The holt 20 and the spacing sleeve 24 additionally serve to impart rigidity to the jack frame.

rlhe castings l2 are provided with bearings 26 through which a shaft 28 extends. The shaft 28 has journaled on its ends which entend beyond the bearings a pair of front wheels 30 for supporting the jai-li at its forward end.

A cross member 32 is secured to the rear The cross member 32 has formed thereon pair of extensions 3st which may be bolted or riveted to the frame members l0. Each end of the cross nieinber 32 is provided with a hub 36 adapted to 1'. tatably receive a 'ivel caster 38. The casters 38 serve to support the rear end of my ack.

lt will be noted that the forward end of my jack is made relatively low whereby it may be conveniently rolled into posi ion beneath the axle of the automobile when the tire thereon is deflated. Ik.. lifting head Il0 is positioned at this low point of thel'lack frame clearly illustrated in Figure 7.

For sui'iporting the lifting head l0 ai. moving it to a raised position, I provide a lifting arm 42, best illustrated in Figure 6 of the drawings. The liftino` arm l2 is pivotedxon bolts el to a relatively high point on the side frame casliugs l2. The lifting armsl2 is really formed of two similar memV` bers connected together by cross members 46 whereby a rigid lifting arm is formed pivotally supported at two points and by making it in one piece, danger of twisting is eliminated. The lifting arm .42 ispivoted to the lifting head 40 in the following described manner.

A lifting head socket 48 is provided with a pivot pin 50 which extends through it and then has each end riveted to a side of the lifting arm 42 as clearly illustrated in Figures 4 and 9 of the drawings. The lifting head socket 48 is provided with an opening' 52 adapted toy receive a shank 54formed on the lifting head 40. The shank 54 is rotatably mounted within theopening 52 of the lifting head socket.

To prevent removal of the shank 54 from the socket an annular V groove 56 is provided around the shank 54. A pointed set screw 58 is screwed through a boss formed on the lifting head socket 48 so `that it engages in the V groove 56. A lock nut 60 .is provided on the set screw 58. The set screw 58 is adjusted so that rotation of the lifting head 40 ii'iay be had but the head cannot be removed from the socket 48. A rotatable lifting head 40 is desirable so that the ack may be swung from side to side while supporting a load.

It is desirable to at all times maintain the lifting head 40 horizontally and to accomplish this result l provide the followingdescribed mechanism.

Formed on the lifting head socket 48 is a pair of arms 62. The arms 62 are pro-- vided with bosses 64 through which extends a pin. 66. Pivoted at one end by bolts 68 or the like to the castings 12 is a pair of stabilizing arms 70. The free ends of the arms 70 are riveted to the-ends ofthe pin 66 which project from the bosses 64 formed on the lifting head socket 48.

The bolts 44 and 68, the pins 50 and 66, the

lifting arms 42 and the stabilizing arms 70 form substantially a parallelogram for the purpose of maintaining the lifting head 40 in a substantially level position.

For actuating the lifting arm 42 vfor the purpose of swinging it on its pivot bolts 44 and thereby raising the lifting head 40 I provide a curved rack bar 72 formed on each side casting 12. In mesh with each rack 72 is what I term an intermediate pinion 74.

-. The pinions 74 are journaled on pins 7 6 which are riveted to bosses 78 formed on the lifting arms 42.

ln mesh with the intermediate pinions 7 4 are a pair of pinions 80 secured to a ratchet wheel shaft 82. The pinions 80 maybe keyed or otherwise fixed relative to the shaft 82. The shaft 82 is journaled in bearings 84 formed on the lifting arms 42.

Secured to the central portion of the shaft 82 and 1,positioned between the bearings .84

the bearings 84. .A lifting pawl link is `rotatably mounted. on each hub 88 and eX-V .tends upwardly between the bolts `44 on whiclrthe lifting arms 42 arepivoted.

The free .ends of the links 90 are pro- `videdrwith a pivotpin 92 on which is pivotally mounted a lifting pawl 94. The free endof-the lift-ing pawl 9 4 is adapted to en- .gage the notches 96 of theratchet -wheel 86.

The lifting pawl 94 is constrained to move into engagement therewith by a spring 98 coiled around the vpin 92 and having parts engaging thelifting pawl 94 and the links O Pivotally mounted on a pin 100 secured to the sides ofthe lifting arm 421is a holding pawl 102. The holding pawl 102 lis constrained to move -into engagement with the notches 96 of the ratchet wheel 86 by a spring 104 coiled around the pin 100 and having partsengaging with the lifting pawl 102 and a portion of the lifting arm frame 42.

From the foregoing description it will be obvious that .oscillation of the links 90 a sufficient distance will cause rotationof the ratchet wheel 86 in the direction of the arrow 106.and reverse movement of the ratchet .wheel will be ,prevented by the holding pawl 102. Rotation of the ratchet wheel 86 will be transmitted through the shaft 82 to the pinions 80 and thenthrough the interbars 72 I provide stoplugs ,108 formed onithe lifting arms. The stop lugs 108 are adapted to engage .the ends of the stabilizing arms 70 where they are pivoted on the bolts 68 to the side frame castings 12.

For causing oscillation-of the links 90 I provide a handle 110 at the rear end of the jack frame. The manner of operatively connecting the handle 110 to the lifting mechanism at the frontend of the jack Vwill now be described in detail. W

Pivoted on a bolt`1l2 at the rear end of the jack is a notchedsector 114. The bolt 112 is supported by ears 116 extending from the feet 84 formedon the cross member 32. Pivoted on .the bolt 112 and positioned on each side of the sector y114 :is a .lever 1-1-8. The levers 118 are connected together by a .casting :120 Aand cap screws 122 and 124. The casting 120 slidably supports a latclliing member 126 adapted to i-coact. with the notches 128r formed in the sector 114. The latching member 126 is provided with a collar 13() and a spring 132 is interposed between this collar and a cross bar 134 of the casting 12() as clearly illustrated in Figure 2. The foregoing construction is for the purpose of constraining the latching member to engage the teeth 128. The latching member 126 is provided with a pair of ears 136 at its upper end.

A pair of handle bars 138 are pivoted to the bolts 122 on the outside of the levers 118. The downwardly extending` ends of the handle bars 138 are provided with notches 140 adapted to swing into position with the cap screws 124 engaging 'the bottoms thereof. A yoke 142 best shown in Figure 6 is adapted to extend around the casting 120, the levers 118 and the handle bars 1387 for the purpose of preventing undesired pivotal movement in one direction of the handle bars 138 with relation to the levers 118. Such movement in an opposite direction is prevented by the bottoms of the notches 140 engaging the cap screws 124.

The operating handle 110 is provided with an extension 144 adapted to be bolted between the upper ends of the handle bars 138 and to serve as a spacer therefor. A latch lover 146 is pivoted at 148 to the handle bars 188. The latch lever 146 has a link connection 150 extending from a pivot bolt 152 thereon to a. pivot bolt 154 extending through the ears 136 of the latching member 126. A rod 156V extends through the latch lever 146 for being engaged by the hand of the operator when he desires to raise the latch member 126 from engagement with a notch 128 in the sector 114. rIhe handle 110 can then bemoved to any desired angle includinga position adjacent the ground and the latch lever 146 can then be released to allow the'latch member 126 to engage another one of the notches 128. in this manner the handle 110 is operatively connected to the sector 114 in any convenient position for proper operation of the jack.

The operating handle 110 is adapted to oscillate on the pivot bolt 112 and this oscillation is transmitted to the lifting pawl links 96 by the following described mechanism. A yoke member 158 is pivoted at lo() to the sector 114. The yoke member 158 extends rearwardly beneath the cross niember 32 which at this point arches up over the yoke member. The rear end of the member 158 has formed thereon Ya screw threaded boss 162. A pair of stop extensions 164 is formed on the yoke member 158 back of the cross member 82. Another stop member 166 is formed on the boss 162 in front f the cross member 82. The stop members 164 limit the reciprocating moveent of the yoke member 158 in one direction mounted between the sides of the and the stop member 166 limits such moveent'in an opposite direction. rlhe purpose of this limitation of movement will hereinafter be more fully described.

On the pivot pin 92 which extends through the lifting pawl links I pivot a yoke meinber 168. The yoke member 168 has formed on its rear end a boss 176 which like the boss 162 on the yoke 158 is internally screw threaded. An operative connection is provided between the yoke members 158 and 168 by a connecting rod 172 having its ends screwed into the bosses 162 and 170. This construction allows for adjustment of the distance between the pivot pins 92 and 160 and such adjustment may be permanently retained by setting the lock nuts 174 against the bosses 162 and 170.

F rom the foregoing description it will be obvious that oscillating` movement of the sector 114 will be transmitted through.- the connecting rod 172 to the linl-s 90 whereby the li ting pawl 94 may be actuated to rotate the ratchet wheel 86 and thus impart lifting movement to the lifting head 40. rhe stops 164 and 166 are provided so that excessive oscillation of the lifting pawl is prevented. n other words, the distance between the stops is but slightly greater than the distance required to move the engaging end of the lifting pawl 94 from one notch 96 of the ratchet wheel 86 to the next one.

For imparting rotation to the ratchet wheel 86 in a direction opposite to the arrow 166 whereby the lifting` head 4() may be lowered, I provide the following described reversing mechanism. A pivot pin 176 is lifting arm 42. Journaled on the pin 176 is a pawl engaging 'lever 178. Vlhe pawl cngaging lever is formed on ahub 18() which extends between bosses 182 formed on the lifting` arm 42 for the purpose of receiving the pivot pin 176. A )air of arms 184 are formed on the hub 186 and a pair oi springs 186 connect these arms to one of the cross members 46 whereby the pawl engaging lever 178 is constrained to move in the direction indicated by the arrow 188.

For preventing the movement just indi- :ated provide apair of cables 196 connected at one end to the arms 184 and cxtending over pulleys 192 jenrnaled on the lifting arm pivot bolts 44. The cables 190 then extend beneath the spacing sleeves 24 and toward the roar of the jai-:fk where they are connected to a reversing foot pedal 194. rl'he pedal 194 is formed on one of a pair of arms 196 which have thforward ends pivotally mounted on the pivot bolt 112 at the rear end of the jack. A pair of curved. links 198 are pivoted at 200 to the arms 196 and extend forwardly and over the pivot bolt 112 as clearly illustrated in Figure 1 of the drawings. A cross member J duty j ack.

202 is provided for the arms 196 to cause their swinging movement to be coincidental. The cables 190 are fastened to the forward ends of the curved links 198. In Figure l it will be noted that the connections of the cables to the links 198 and the pivot connection 200 are on a line below the pivot bolt 112 whereby the pull exerted oii the cables 190 serve to maintain the reversing foot pedal 194 in the posit-ion illustrated in full lines due yto a line between the connection of the cable to the link and the pivot connection 200 passing across the center of the pivot bolt 112. When the operator engages the under side of the pedal 194 with his toe and lifts it, the levers 196 will move the links 198 to the dotted line position due to the pull of the springs 186.

When the pedal 194 is raised and the cables 190 consequently Slackened the pawl engaging lever 178 will move as indicated by the arrow 188 to the position illustrated in Figure 10. In this position the outer end of thelever 178 engages an extension 204 -formed on the lifting pawl 94l anda boss 206 on the lever engages an extension 208 formed on the holding pawl 102. The operation of the reversing mechanism just described will hereinafter be more fully described.

In Figures 15 and 16 of my drawings, I have illust-rated a modied form of jack provided with gearing, which I will now describe in detail, for the purpose of a heavy In these two figures, parts coi'- responding to similar partsof the jack illustrated in the figures thus far rdescribed have been given the saine reference numerals with the addition of the character (0.

In this type of jack7 the ratchet wheel shaft 82a is journalled in the bearing portions 84@ of the lifting arm members 42a. The pinions a may comprise teeth milled into van enlarged central portion of the shaft 82aand the ratchet wheel 86a is keyed or otherwise suitably secured to the shaft 82a. The pinions 74a which mesh with the curved rack bar 72a are journalled on the pins 76a, but instead of meshing directly with the pinions 80a, they are provided with gears 75 which mesh with the pinions 80a. rlhis gives a speed reduction in my jack making it suitable for use in raising the wheels of heavy trucks. For supporting the pinions 74a and gears 75, each of the pins 76a is positioned with one end in the lifting arm 42a and the other end in an ear 43a constituting the end of a yoke 43 which is formed on the lifting arm as clearly shown and extends around the pinion 7 4a and the gear 75. lThe ear 43a is shown in dotted lines in Figure 15, the ear being actually nearer the observer than the section line upon which Figure 15 is cut. This construction provides a substantial support for the pinion and gear.

Practical operation In the practical operation of my improved lifting jack, the lifting head 40 normally lowered to the position illustrated in Figure 7. rIhis position is comparatively low and the forward end of the jack can therefore be wheeled'into position beneath the axle of an automobile wheel or the like for the lifting of such axle. The operating handle can be moved to the most convenient position relative tothe sector 114 for operation by the user of the jack. It may here be mentioned that the jack can be placed under one of the axles of an automobile with the handle 110 extending from beneath the running board in which case the handle 110 would necessarily need to be adjusted to alow position in order to have room for proper operation. The sector 114 may then be oscillated for raising the liftingy head 40. If desired the latching lever 146 can be moved in the direction of the arrow 210 is rotated in the direction of the arrow 1076 by the lifting' pawl 94 and reverse rotationk Mini thereof relative to the lifting arm 42 is prevented by the holding pawl 102.

t will be understood of course7 that the pawl springs 98 and 104 actuate their respective pawls to engage the periphery of the ratchet wheel 86. As shown in Figure 7 the lever 178 is heldin position so as to interfere with the action ofthe pawls and is held in such position by the cables and foot pedal 194, the pedaland links 198 assuming the full line position illustrated in Figure 1.

Then it is desired to utilize the pawl reversing mechanism for the purpose of lowering the lifting head 40 it is merely necessary to raise up on the reversing pedal194 for allowing the springs 186 to act on the Vreversing lever 178. 'Ihe springs 186 are lifting head 40 is illustrated in Figures 10 to 13 inclusive of the drawings.

Assuming that the pawls are in theposition illustrated in Figure 7 of the drawings the reversing lever 178 upon being released by upward movement of the reversing pedal 194 will move to the position illustrated in Figure 10. In the position just referred to the lever 178 engages the extension 204 of the lifting pawl 94 and disengages it from the ratchet wheel 86. The holdingpawl 102 is now holding' the load on the lifting head 40 by reason of its engagement with one of the notches 96 of the ratchet wheel 8G. The lifting pawl levers 90 are now moved in the direction of the arrow 214 as indicated in F igure 11 which allows the extension 206- on the lever 17 8 to engage the extension 208 on the holding pawl 102. rlShe lifting' pawl 94 is now free to engage the next succeeding notch of the ratchet wheel 86 as illustrated in Figure 12 of the drawings and the ratchet wheel will he moved a slight distance in the direction of the arrow 216 as movement of the lifting' pawl is continued. This slight movement will release the load from the holdinp; pawl 102 so that the lever 17 S causes it to disengage the ratchet wheel 86. The lifting pawl links 90 may then be moved in an opposite direction as indicated by the arrow 218 which allows the load on the load liftingV head 40 to carry the'ratchet wheel- 86 in the same direction as illustrated in Figure 13. As this movement continues, the next succeeding notch of the ratchet wheel 8G will entrare the holding); pawl 102 and the cycle of operations just described will be repeated as the lilting; pawl links 90 are oscillated by the' operating' handle 110.

As soon as the lifting` head 40 is lowered to a position where it no longer engages the axle of the automobile due to the axle now being' supported on the wheels thereon. the load will be removed from the ratchet wheel 8d In this event wher the parts assume the position illustrated in Figure 13. the tension of the springs 186 act-ing' through the lever 17S is `treat enough to overcome the force of the pawl springs 9S and 104 and them-doy move the lifting' pawl 94 and the ho; .ina pawl 102 to the dotted line positions illustrated. Thereupon the ratchet wheel S6 is free to rotate and the weight of the lifting' arm and lifting' head will canse the lifting; head to be lowered to its lowest position without further operation of the ha, ile 110.

Dagraamnatical illust/ration of Hic actionl of my planetary gedrang In Figure 14 of the drawings l have illustrated the elements of my 'iaclr in l iap;rar.i The reference characters on this 'ligure indicate the same parts shown in the other views of the drawings. The full line position of the lifting' arm 42 and all of its associated parts indicate the lowered position of the lifting head 40. The dotted .line position illustrates the saine parts when the lifting head 40 is in raised position.

The pivot pin 92 of the liftingr pawl links 90 moves during its oscillation from the position indicated to the center of the pivot bolt 44 as indicated by the line 220. It will be noted that this line is on an angle substantially he same as the angle of the liftingarm 42. The pull of the rod 172 is substantially horizontal so that it pulls at an angle on the pivot pin 92 which considerably increases the leverage obtained in the lifting pawl 94. However, it will be noted that the liftin arm 42 is also at an angle and therefore does not require quite as much force for raising' it as when it is moved to the horizontal position indicated at 222. lfihen in the position 222 the travel of the pivot pin 92 is substantially parallel to the pull of the rod 17 2 as indicated by the line 224 whereby substantially the same amount of force is required on the rod 172 regardless of the position of the lifting arm.

When the lifting arm is raised to the dotted line position the travel of the pin 92 will be at an angle as indicated by the line 2,26 so that the force required for raising' the lifting head is still. the same. This construction provides an evenness of operation of the jack without complicating its construction in any manner.

It is desirable to have the rack bars 72 a considerable distance from the pivot bolts 44 of the lifting' arms 42 which would necessitate the ratchet wheel S6 being' too close to the `ground if the pinions 80 were in mesh with the rack bars. l have therefore provided intermediate pinions 74 so that the ratchet wheel 8G may be of substantial diameter and the rack bars 72 may be comparatively low and yet the parts are properly associated together throiurh the medium of the intermediate pinions 74 for the purpose of actuating' the lifting arm.

From the description it will be obvious that the handle 13S may be conveniently lowered to the dotted line position illustrated in Figure 1 for the purpose of compactly folding' the jack so that it can be Crate-'l for shipping without disaseeinbling)` anv of the parts.

Sonie changes may be made in the construction and arrangement of the various parts of my invention without departing from thc real spirit and purpose of my invention and it is my intention to cover by my claims, any mo 'tied forms of structure or use of ine-- chanieal equivalents7 which may be reasonably included within their scope.

l claim as my invention:

1. A lifting' jack comprising` a frame? a downwardly curved rack bar thereon, havingr its ends in a substantially horizontal plane, a lifting' arm pivoted to said flame7 i ratchet wheel and a pinion journaled on ad lifting arm, means for actuating said atchet wheel for rotating said pinion and n intermediate pinion associated with said first pinion and with said curved rack bar for causing pivotal movement of said lifting arm upon such actuation.

2. :i lifting jack comprising a Wheel mounted frame, a downwardly curved rack bar thereon having ends in a plane substantially horizontal mechanism mounted on one end of said frame, said mechanism comprising a lifting arm pivoted to said frame, a ratchet Wheel and a pinion ournaled on said lifting arm, means for actuating said ratchet Wheel for rotating said pinion and an intermediate pinion associated With said first pinion and with said curved rack bar for `ausing pivotal movement of said lifting arm upon such actuation.

3. A lifting jack comprising a frame, a curved rack bar thereon having ends arranged in a substantially horizontal plane and close to the bottom of said frame, a lifting arm pivoted to said frame, a ratchet Wheel and a pinion journaled on said lifting arm, means for actuating said ratchet wheel for rotating said pinion said pinion being spaced from said rack bar and an intermediate pinion associated With saidfirst pinion and With said curved rack bar for causing pivotal movement of said lifting arm upon such actuation, said intermediate pinion comprising tWo parts, one part meshing with the curved rack bar and the other part meshineV with said first mentioned pin ion.

4. A lifting ack comprising the combination of a horizontal frame, a lifting arm pivoted thereto, a lifting head mounted on the free end thereof, a curved rack bar secured to said frame adjacent the bottom thereof, said rack bar having ends in a substantially horizontal plane rotatable means on said lifting arm, said means being operatively associated With said rack bar whereby rotation of the means imparts lifting movement to the lifting arm and means to rotate said rotatable means, step by step, in either direction.

5. A; lifting jack comprising the combina-1 tion of horizontal frame, a lifting arm pivoted thereto, a lifting head pivoted to the free end thereof, means for maintaining said lifting head in vertical position throughout the pivotal movement of the lifting arm, a curved rack bar secured to said frame adjacent the bottom thereof, said rack bar hav ing` ends in a substantially horizontally plane rotatable means on said lifting arm, said means being operatively associated With said rack bar whereby rotation of the means imparts lifting movement to the lifting arm Y member carried by another of said corners, y

a curved rack bar on said frame, adjacent the bottom thereof and having ends lying, in a substantially horizontal plane, means mounted on the remaining corner of said triangular lifting arm and operatively associated With said rack bar for causing the lifting head to be raised or lowered When said means is rotated and mechanism for imparting rotation in the desired direction to said means.

Des Moines, Iowa, September 30, 1927.

LEONARD D.' NLSON.

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