US1648036A - Trip mechanism for jacks - Google Patents

Description

Nov. 8, 1927.

G. E. WEAVER ET AL TRIP MECHANISM FOR JACKS NJ W Filed July 14 1926 5 Sheets$heet l Nov. 8, 1927. 1,648,036

G. E. WEAVER ET AL TRIP MECHANISM FOR JACKS Filed July 14, 1926 3 Sheets-Sheet 2 Nov. 8, 1927..

G. E. WEAVER ET AL TRIP MECHANISM FOR JACKS 3 Sheets-Sheet 3 Filed July 14, 1925 Patented Nov. 8, 1927.

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G-AILARD E. WEAVER AND ALBERT R. SQUYER, OF SPRENGFIELD; ILLINOIS, ASSIGNORS H I T 1V EA ER MANUFACTURING COMPANY, OF SPRINGFIELD, ILLINOIS, A CORPORA' TION' OF ILLINOIS.

TRIP MECHANISM FOR JACKS.

Application filed July 14, 1926. Serial No. 122,349.

Our invention relates to lifting jacks, more particularly truck-jacks, and pertains especially to novel and improved tripping mechanisms therefor, whereby the appliance may be easily operated to elevate the load or to cause its descent.

One aim of the invention is to provide a construction of this general character which is simple in structure, which can be easily operated by the foot, and which, works at least in part automatically, economy in manufacture and unlikelihood of becoming damaged or injured in ordinary service being also salient features of the new device.

To permit those trained in this art to have a full and complete understanding of the invention and its various advantages, in the accompanying drawings forming a part of this specification and throughout the several views of which like reference characters have been employed to designate the same parts, a present desirable and preferred embodiment of the invention has been shown in detail.

In these drawings:

Figure 1 is a lan view oft-he truclejack with the load-litting parts in lowered position;

Figure 2 is a side elevation of the ap pliance with the members in the same po sition;

Figure 3 is a longitudinal section through the truck-j ack with the cooperating elements in load-elevated positions;

Figure 4: is a similar section indicating the relation of the parts for lowering the load;

Figure 5 is an end elevation of the appliance;

Figure 6 is an enlarged section on line 66 of Figure 2;

Figure 7 is an enlarged horizontal section on line 7-7 of Figure 3;

Figure 8 is a detail view oi the pawl and ratchet mechanism showmg the parts 111 position for elevating the load; and

Figure 9 is a similar view illustratingthe same parts in position forlowering the load.

Referring to the plurality of views of these drawings, it will be perceived that the truckjack includes a horizontal mainframe, comprising an open, front, end casting-21, a rear end casting 22, and spaced, parallel con meeting-bars 23 and 24L bolted or otherwise secured to these two terminal members 21 and 22.

A cross-member 25, hinged to the casting 21 at 26, accommodates an axle 27 on the opposite ends ofwhich are rotatably mounted a pair of carrying-wheels The bearing-member 35, at its lower end,

is rockingly mounted on a cross-shaft 37 carried in hearings in spaced depending portions of the casting 22, whereby the handle 34 may be swung up and down in a vertical plane around the axis, of the supporting shaft 37' and it may also be turned about its own axisin the bearing-member 35, the latter capacity, as will be readily understood, bemg employed to effect the steering of the truck by the turning ofthe wheels 28, 28

through the medium of the connecting link The upward swinging or rocking movement of such handleis limited or restricted by reason of outstanding lugs38, 38 on the bearing-member 35 engaging the end of the adjacent casting 22, all as has been clearly illustrated, for example, in Figure 2. i

The rear end of the truckirame is supported by a double castor-wheel construction 39 mounted to swivel around a verticallyof parallel bars 46, 47 riveted to the casting at 18, 4:8 and fulcrumed at the outer sides oi the main-frame bars 23 and 2st on aligned bolts 49, 51 extending through registering holes in the elements involved, thebar 47 be ing of sutiicient length to extend an apprecentrally pivoted 9o disposed bolt 41, whereby the truck may be readily wheeled into any desired position'by ciable distance beyond its fulcrum to a convenient position where it is fitted with a footpiece or pedal 52.

Such lever casting 45 is connected by a link 53 to an extension of a ratchet-segment 54 fulcrumed on the casting 21 on a suitablysupported cross-shaft 55, such member 54 having ratchet-teeth on its substantially semi-circular periphery.

Obviously, the rocking or turning of the ratchet-segment will effect the raising or lowering of the lever 45, 46, 47 causing a corresponding elvation or descent of the saddle 42 and the load imposed on it.

To bring about the step by step turning of the ratchet-segment and a comparable movemnt of the load, the following specified cooperating instrnmentalities are employed.

A bell-crank lever 56 is fulcrumed in the casting 21 on a cross-shaft 57 and the shorter, upper arm thereof has a pawl 58 r'ockingly mounted thereon and adapted to cooperate with the teeth of the ratchet-segment to produce the intermittent or step by step action of the latter.

Such pawlor dog is yieldingly held to its work by a short, coiled spring 59 connected thereto at one end and to the casting 21 at the other endas is illustrated perhaps most clearly in Figure 1. K

The longer, depending arm of such bellc ranklever 'has'a long link 61 pivotally connected thereto at '62, the opposite end of the link being similarly connected at 63 between spaced ears to the bearing-member hereinabove referred to.

A spring 64, encircling the link, bears at one end against an adjustable, screwth'readed member65 on the link and presses at its other end against an abutment 66 forming part'of the apertured casting 22, where by the spring tends to hold the pawl or dog in elevated position ready to do its work when rocked downwardly.

"Obviously, it is essential to have a holding dog or pawl to coact with the ratchetsegment during the retraction of the lifting pawl, and, accordingly, such an element 67 is provided and hinged or fulcrumed at 68 on the casting 21 being normally pulled up to its work, that is toward the companion segment, by a coiled, contractile spring 69 fastened thereto and to the casting.

Such holding or locking dog or pawl has a lateral ing 71 thereon in the path of movement of the end of a curved, cam arm 72 fulerumed on the casting 21 at 57 and having an extension arm 73 connected to a link 74 slidable in aligned hearings in the spaced arm 75 and 76 of a yoke 77 rigid with :1

'flatbar 78 pivotally connected at 79 to the end of an arm 81 fixedly mounted on the inner end of a short shaft 82 rockingly accommodated in a bearing 88 forming'part of the casting 22, the outer end of such shaft having a knurled, right-angle foot-piece or pedal 84 fixed thereon and having an adjustable abutment 85 in the plane of movement of the lever-bar 47.

Link 74 has a pin 86 extended therethrough and a coiled spring 87 encircles the link bearing at its rear end against the pin and at its front end against the part 76 of the yoke.

No difficulty will be encountered in understanding how the truck-jack is rolled into place by manipulation of the handle, its turning movements producing the steering action of the carrying-wheels at "the front or opposite end of the truck.

The load-lifting and lowering operations occur practically as follows Assuming that the truck-jack has been moved into proper position so that the saddle 42 is directly below the load, for example, the axle or differential of an automobile, the operator presses downwardly with his foot on the pedal or footpiece 52 causing a rapid elevation of the other end of the long lever 45, 46, 47, which carries the saddle or seat upwardly until the latter engages or comes up to the body or load to be lifted.

Such rocking of the long lever automatically swings the ratchet-segment into a corresponding position, the dogs or pawls idly riding over the teeth, but the locking dog performs its'holding function when the lever reaches the heightof the saddle desired.

Thus a quick adjustment of the saddle to the load is easily accomplished.

During such preliminary or initial raisin; of the saddle and during its further step by step elevation about to be described, the angular foot-piece 84 occupies the position shown in Figures 1, 2 and 3 with 'the strain removed from spring 87 so that the cammember 72 remains in the position shown in Figure 8.

To raise the load, the operator rocks handle 34 up and down in a vertical plane disposed lengthwise the truck and the resulting longitudinal backward and forward movements of link 61 rock the bell-crank lever 56 and its lifting-pawl 58 in the usual way to raise the load step by step, the holding-pawl 67 performing its customary functi on'of holding or locking the segment while the lifting-dog recedes to engage a new tooth, and idly riding over the segment teeth during the lifting turning thereof.

Taking for granted, that the load has thus been raised and that it is now desired to lower it step by step, the workman turns the angular foot-piece 84 forwardly with his foot thereby pulling the yoke 77 rearwardly and compressing the spring 87 between the yoke-arm 76 and the pin 86, the bar 78 passing slightly beyond dead center with respect to shaft 82,'as shown in Figure 4, so that the parts will maintain the posiill tions indicated in that figure of the drawings until released automatically or by foot as will be explained.

Such compression of spring 66lroclrs cam 72 downwardly so that its lower end strikes the holdin doglug 71, but the spring is not strong enough to release such holdingdog from the tooth of the segment against which it bears, because these teeth are slight- 1y undercut and because the load imposes too great a friction between the tooth and dog. a

As the handle 34 is rocked downwardly, a finger 50 on the side of the pawl 58 rides on the under surface of cam 72 and the pawl is thereby permitted to escape one tooth of the segment but engages the second tooth, the spring 87 acting on the cam being adequately strong to accomplish this result.

The cam is so shaped, however, that the lifting-dog comes into contact with the proper tooth of the segment and assumes the load, thus taking it ofi of the holding-dog and then the latter, under the action or the spring 87 acting thereon through the end of the cam, is retracted, as shown in Figure 9, so that the reverse rocking of the handle permits pawl 58 to lower the load one full notch or tooth, but as it does so, its finger or lug 50 forces the cam 72 over to allow the locking-dog to again come into play and to hold the load during the next advance movement of pawl 58.

Thus the load is permitted to descend step by step and, as soon as it is removed from the jack, the saddle drops automatically to its lowermostposition, because we do not then have the load present to overpower the action of spring 87 and the latter is strong enough under such circumstances to retract both pawls permitting the segment to rock freely allowing the load lever to descend to its lowest position as shown, for example, in Figure 2.

So long as the load is imposed on the saddle, there is no danger of the latter descending except slowly step by step by the rocking action of the handle 34.

Just before the lever bar 47 reaches its lowermost position, its top edge strikes the abutment 85 and restores the foot-piece 84': and its associated trip mechanism to loadlifting relation, the spring 87 quickly accomplishing this result just as soon as bar 78 passes the dead center of shaft 82, whereby the jack is again ready to raise a load without attention on the part of the operator to the tripping appliance.

If, after the load has been partly lowered, it becomes desirable to raise it again, this can be easily brought about, without fully lowering the load, by merely turning the toot-piece 84 by foot to lifting position, all as will be readily understood.

While only one embodiment of the in vention has herein been presented, it is to be understood that it is susceptible of a variety of embodiments differing from one changes may be made in the appliance illustrated and described without departure from the heart and essence of the invention and without the sacrifice or any of its substantial benefits and advantages.

lVe claim:

1. In a jack, the combination of load en gaging means, a movable handle, operating means between said handle and load-engaging means permitting said handle to raise or lower said load-engaging means, footactuated means to cause said operating means to assume its load-lowering condition, and means to restore said operating means automatically to load-lifting relation after having been in lOEtCl-lOWGllDg condition.

2. In a jack, the combination of load-engaging means, a movable handle, operating means permitting said handle to raise or lower said lo ad-engaging means step by step, means enabling the operator to preliminarily raise said load-engaging means quick- 1y to the load without resorting to the step by step movement, and means actuated by said preliminary-raising means to restore said operating means automatically to loadli'tting relation after having been in loadlowering condition.

3. In a jack, the combination of a loadengaging means, a movable handle, operating means permitting said handle to raise or lower said load-engaging means step by step, means enabling the operator to preliminarily raise said load-engaging means quickly to the load without resorting to the step by step movement, and means actuated by said preliminary raising means to restore said operating means automatically to load lifting condition when said load-engaging means approaches its lowermost position.

4. In a jack, the combination of load-engaging means, a movable handle, operating means permitting said handle to raise or lower said load-engaging means including a tripnneclianism constructed to be shifted beyond dead-center to effect the load-lowering operation, means actuated by the operator to move said trip-mechanism to loadlowering condition, and means to move said trip-mechanism back past dead-center auto matically into load-raising position when the load-engaging means approaches its lowest position.

5. In a jack, the combination of loadenmeans permitting said handle to raise or lower said load-engaging means including gaging means, a movable handle, operating a trip-mechanism adapted to be actuated by the operator to selectively govern the action of said operating means whereby to cause the latter to raise or to lower the load, means 5 to maintain said trip-mechanism in loadlowering relation after having been shifted by the operator into such condition, and

means to automatically shift said tripmechanism to load-raising relation when said load-engaging means approaches its lowermost position.

GAILARD E. \VEAVE'R. ALBERT R. SQUYER.

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