US1949095A - Lifting jack - Google Patents

Description

Feb. 27, 1934. w. H. WALKER LIFTING JACK Filed April 22, 1953 4 Sheets-Sheet 1 Inlfen'ta' WIBIIZ/Mw j orne a Feb. 27, 1934. w, H, WALKER LIFTING JACK 4 Sheets-Sheet 2 Filed April 22, I933 I I1 1 n W. H. WALKER LIFTING JACK Filed April 22, 1933 4 Sheets-Sheet 5 wrek wi 3H 4 R M AW Feb. 27, 1934.

Feb. 27, 1934. w; H. WALKER LIFTING JACK Filed April 22, 1933 4 Sheets-Sheet 4 2%??? Qfifler I 45M Patented Feb. 27, 1934 UNITED STATES PATENT OFFICE LIFTIN G JACK Application April 22, 1933.

10 Claims.

This invention relates to certain new and useful improvements in lifting jacks, and more par ticularly to an improved jack of the type especially adapted for use about garages and repair shops for quickly and easily lifting heavy loads. This type of jack is mounted on a carriage and is provided with a relatively long, permanently attached operating handle by means of which the jack may be pushed into position beneath the load, elevated or lowered and moved while supporting the load. The jack is simple and compact, and is designed to have a minimum over-all height when lowered so that it may be moved into position beneath very low hanging loads.

' Briefly described, the jack comprises a pivotally mounted lifting arm in the form of a modified bell-crank lever adapted to support the load at the end of its longer arm and formed in its shorter arm with an internal arcuate rack which is in mesh with a rotatable driving pinion. The pinion is carried on a shaft which is mounted in the carriage and projects through an opening in the lifting lever. The operating handle is pivoted on the same axis as this shaft and is adapted tobe swung or oscillated through a small are, pawl and ratchet mechanism being provided to impart step by step rotation to the driving pinion in one direction or the other as the operating handle is oscillated.

The principal object of the invention is to provide an improved lifting jack of the type briefly described hereinabove and disclosed more in detail in the specifications which follow.

Another object is to provide an internal rack and pinion operating mechanism'for swinging the main lifting lever.

Another object is to provide an improved reversing mechanism for either lifting or lowering the load-supporting lever when the operating handle is oscillated.

Another object is to provide an improved quicklift mechanism for swiftly moving the load-supporting member upwardly into engagement with the load.

Other objects and advantages of this invention will be more apparent from the following detailed description of one approved form of mechanism constructed and operating according to the principles of this invention. In the accompanying drawings: 7

Fig. 1 is a side elevation of the complete jack.

Fig. 2 is a plan view of the jack, on a larger scale, a portion of the operating handle being broken away.

Fig. 2 is a plan view of the remainder of the Serial No. 667,480

operating handle, this view being substantially an extension of Fig. 2.

Fig. 3 is a partial vertical section, this view being taken substantially on the line 3-3 of Fig. 2.

Fig. 4 is a side elevation of a portion of the operating handle, this view being substantially an extension of the right hand portion of Fig. 3.

Fig. 5 is a partial vertical section through a portion of the handle, this view being taken substantially on the line 5-5 of Fig. 2.

Fig. 6 is a detail vertical section, taken substantially on the line 6-6 of Fig. 5.

Fig. 7 is a partial vertical section taken substantially on the line 7--7 of Fig. 2.

Fig. 8 is a transverse vertical section taken substantially on the line 88 of Fig. 3, and on a larger scale.

Fig. 9 is a perspective view, partially broken away, of the pinion-shaft assembly.

Fig. 10 is a perspective view of one of the pawls or dogs.

Figs. 11 to 14 inclusive are similar diagrammatic views showing the reversing mechanism in different operative positions.

The carriage comprises a pair of similar side frames 1 and 2 which are of greatest height adjacent their rear ends and taper toward the narrow front end portions which are connected and spaced apart by the front axle 3 which passes through hubs 4 on the side frames and is pinned thereto at 5. Wheels 6 are journaled on the outwardly extending ends of the axle 3 and are held in place by cotter pins 7, or other suitable fasteners. The ends of the side frames project forwardly to form feet 8 so that the jack may he stood up on end when not in use. Rollers 9 are journaledon the outwardly projecting end portions of a rear axle 10 mounted through the rear portion of the side frames. Intermediate portions of the side frames are connected and spaced apart by the several pins and shafts hereinafter described.

The main lifting member 11 is in the form of a modified bell-crank lever having a hub 12 formed in its upper rear portion and journaled on the enlarged central portion of a fulcrum pin 13 which has reduced end portions 14 extending through bosses 15 formed on the respective side frames, the fulcrum pin being clamped in position between the side frames by means of nuts 16 threaded on the opposite end portions of the pin. The long forwardly projecting arm 1'? of the lifting lever 11 is pivoted at 18 to the lifting head or cap 19which may be of any desired form and is preferably provided with the spaced apart upwardly extending load-supporting fingers 20. A pair of similar side links 21 have forward ends pivoted at 22 to the head 19 and their rear ends pivoted at 23 to the respective side frames 1 and 2. These links cooperate with the arm 17 of the lifting lever to give a parallel motion to the load supporting head 19, that is, they keep the head horizontal in all of its raised or lowered positions. The head is shown lowered in Fig. 3, and is shown in dotted lines in its elevated position in Fig. 1. It will be noted that when this head is lowered to its extreme position it is substantially no higher than the tops of the wheels 6 at the front end of the carriage so that this load-supporting head may be pushed beneath very low hanging loads. The enlarged lower rear portion of the lifting member 11 is formed beneath the supporting hub 12 with an arcuate opening or slot 24, and a concaved internal rack or gear segment 25 is formed in the lower portion of this opening. This rack is arcuate and substantially centered in the aXis of fulcrum pin 13, the several teeth 26 of the rack projecting inwardly and upwardly toward this fulcrum pin or axis.

The rotatable operating assembly shown in perspective in Fig. 9, and shown in position within the carriage in Fig. 8 comprises a pinion shaft 2'7 which, in the form here shown, has teeth 28 formed directly on this shaft to provide a driving pinion which meshes with the teeth 26 of the internal rack 25 in the lifting lever. In view of the fact that the load is always carried by one face of each of the intermeshing teeth of the pinion and rack, these teeth are given the special configuration shown in the drawings. The somewhat reduced end portions 29 of pinion shaft 2'7 are journaled in bosses 30 formed in the respective side frames 1 and 2. The ratchet wheel 31 is broached out to fit over the extensions 32 of pinion teeth 28 (which are of slightly reduced diameter) these tooth extensions forming keys for rigidly securing the ratchet wheel 31 to the pinion shaft. The pinion 28 and ratchet 31 are so positioned intermediate the ends of the pinion shaft 27 that the driving pinion 28 will be positioned within the opening 24 in the lifting lever 11 and centered substantially in the central vertical plane of this lever, whereas the ratchet wheel 31 will be positioned at one side of the lever, as best shown in Fig. 8.

The operating handle comprises a pair of handle- socket members 33 and 34 which are connected at their rear or outer ends by an inner yoke 35, the inner or forward ends of these socket members being rotatably journaled on the cylindrical sections 27' of pinion shaft 2'? just inside of the respective side frames 1 and 2, as best shown in Fig. 8. The similar side bar members 36 and 37 of the handle are secured at their forward ends in the recessed outer sides of the socket members 33 and 34 by means of bolts 38 which pass through the side bars, socket members and yoke so as to secure these several parts together. The side bars 36 and 37 converge inwardly and rearwardly toward one another and are secured by bolts 39 to the opposite sides of the inner end of the handle extension bar 40. Suitable handle members 41 of wood orv other suitable material are secured to the opposite sides of the extreme outer or rear end of the bar 49, thus completing the operating lever. In order to manipulate the raising and lowering mechanism, this operating handle is adapted to be reciprocated or oscillated vertically, different positions of the handle being indicated in dotted lines in Fig. 1. The respective downward and upward swinging movements of the operating handle are limited by the stops 42 and 43 formed on the side frames 1 and 2. By a continued upward movement of the handle after it has been engaged with the stops 43, the rear end of the carriage may be raised so as to support same entirely by the front wheels 6 and thus facilitate moving the carriage into position.

An operating pawl or dog 44 is journaled on a stud 45 mounted in and projecting inwardly from the handle socket member 33 so that the pawl will be positioned substantially in the vertical plane of ratchet wheel 31. This pawl may be of the form shown in Fig. 10, having a tooth 46 shaped to engage the teeth of ratchet 31, and being formed with a lug or projection 47 on one side thereof to cooperate with the rotary reversing member hereinafter described. A torsion spring 48 which is anchored at one end and engages the pivoted pawl at the other tends to swing the pawl into engagement with ratchet wheel 31 at all times. A holding pawl 49, which may be similar in all respects to the operating pawl 44 is mounted on a pin 50 which extends through bosses 51 formed in the side frames 1 and 2 and is secured in place by nuts 52 on its opposite ends. A spacer 53 on pin 50 positions the holding pawl 49 on shaft 50 so that it will be in the vertical plane of ratchet wheel 31. The holding pawl is normally forced yieldingly into engagement with the ratchet wheel by means of the torsion spring 54.

In order to elevate the head 19, and the load carried thereby, the operating handle is oscillated or swung up and down. During the downward stroke the operating pawl 44 will engage a tooth of ratchet wheel 31 and cause the ratchet wheel and driving pinion 28 to rotate with the handle through this short downward are, thus swinging the lifting bell-crank 11 upwardly through a short arc. The holding pawl 49 will snap outwardly over the teeth of the ratchet, but will engage another tooth of the ratchet wheel to hold the load elevated during the succeeding upward movement of the operating handle, during which movement the operating pawl 44 will ride outwardly over the teeth of the ratchet wheel. In this manner, continuous swinging movement of the operating handle will cause a step by step upward swinging movement of the lifting lever 11 until head 19 has been raised to the elevated position shown in dotted lines in Fig. 1. A pinion tooth 28 will engage with the solid portion 26 of lever 11 beyond the last tooth 26 of the rack to limit the upward movement of the lever.

A reversing mechanism is provided so that this same up and down swinging movement of the operating handle may be utilized to lower the lifting head and the load supported thereby. This reversing mechanism comprises a rotary reversing member 55 which has a hub 56 journaled sitely projecting fingers or cam members 58 and 59 which, in certain positions of the reversing member, are adapted to engage and cooperate with the lugs 4'7 on the respective pawls 49 and 44. The link or rod 60 has its forward laterally extending end portion 61 secured in an ear 62 I?! projecting upwardly from reversing member 55, the rod 60 extending rearwardly through an opening 63 in handle yoke 35 and having its rear end portion 64 secured in ear 65 projecting upwardly from casing 66 which houses the reversing spring 67. The spring 6'7 surrounds the inner end of a link or rod 68 which projects through the rear end 69 of casing 66, the spring being confined between this end 69 of the casing and a nut 70 adjustably threaded on rod 68. The rear end 71 of a rod 68 is secured to a slide member 72 mounted on the side handle bar 36 (see Fig. 3). A reversing lever 73 is pivotally mounted in a bracket '74 secured to one side of handle bar 40 adjacent the hand grip 41. A link or' rod 75 connects the reversing lever 73 with the slide member '72.

During the normal elevating operation of the jack, the reversing lever 73 is swung forwardly to the position shown in Figs. 1, 2 and 4. When the lever is in this position the reversing spring 67 is not under compression, and as the operating handle is oscillated up and down the pivoted reversing member 55 will swing with the handle between the solid and dotted line positions shown in Fig. 11. At such times it remains out of engagement with the lugs 47 on the pawls and these pawls operate as already described to permit a step by step upward movement of the'elevating lever.

When the jack is to be lowered, the reversing lever 73 is swung rearwardly, or to the dotted line position shown in Fig. 2 This will draw the slide '72 to the rear and through link 68 will place the reversing spring 6'7 under compression. The compression of this spring will tend to rotate the reversing member 55 in a clockwise direction so as to bring the finger or cam 58 into engagement with lug 47 on the holding pawl 49, as shown in Fig. 12. However, as long as the load is supported by this holding pawl (through its engagement with the ratchet wheel 31,) the reversing member 55 will be unable to force the holding pawl 49 out of engagement with the ratchet wheel. The operating handle is now swung downwardly, and the operating pawl 44, if not already in engagement with the ratchet wheel will move'into engagement with a tooth of the ratchet, as shown in solid lines in Fig. 13. Continued downward movement of the operating handle will transfer the load from the holding pawl to the operating pawl 44 so that when the parts have reached the position shown in dotted lines in Fig. 13, the spring actuated reversing member 55 will now operate to throw the holding pawl 49 out to the dotted line position so that its lug 47 will ride onto the cam member 58.

During the following upward stroke of the operating handle, the ratchet 31 and driving pinion 28 will move with the handle and operating pawl 44 through a short counter-clockwise are, thus imparting a lowering step to the jack members and the load carried thereby. I'he lug 47 on operating pawl 44 will engage the cam finger 59 on reversing member 55 and move this member with it in a counter-clockwise direction. even though the reversing spring 67 is still under compression. This counter-clockwise movement of cam finger 58 will permit the holding pawl 49 to again swing into engagement with another tooth of ratchet wheel 31, the movements being from the solid line position shown in Fig. 14 to the dotted line positions. As soon as the load has been accepted by holding pawl 49, the operatlig pawl 44 will be released so that the spring actuated reversing member 55 will now operate to swing in a clockwise direction and throw out the operating pawl 44, which will ride up over the cam finger 59, as shown in solid lines in Fig. 12. The shouldered portion 88 on reversing member 55 is adapted to engage a fixed stop 89 to prevent excessive rotation of the reversing member under the influence of spring 67. On the next succeeding downward swinging movement of the operating handle, the operating pawl 44 will ride down from the cam 59 from the solid line position shown in Fig. 12 to the position shown in Fig. 13, thus engaging with another tooth of the ratchet 31, after which the cycle of operations just described will be repeated. In this manner the load will be lowered step by step. When the jack has been lowered, it is merely necessary to swing the reversing lever 73 back to the normal position shown in the drawings and the jack is again ready for an elevating operation.

Since this jack is very powerful, the elevating movement of the lifting head is necessarily proportionately slow and it is desirable to provide means for quickly elevating the head until it is in position to accept the load. For this purpose an auxiliary quick-lift mechanism is provided. A chain 76, or other suitable flexible member, is anchored at one end 77 to the shorter arm of the bell-crank lever 11. This chain is passed around a suitable guiding or direction changing device, and is attached at its other end 78 to a pull rod 79 extending rearwardly along the operating handle. In the example here shown, the direction changing device comprises a sleeve 80 rotatably positioned on the pinion shaft 27 between driving pinion 28 and the handle-socket member 34. The pull rod 79 extends rearwardlythrough a guide 81 on the handle and is attached at its rear end to a slide member 83 mounted on the rear handle bar 40. The slide 83 is provided with suitable laterally extending hand grips 84. A tension spring 85 surrounds a portion of pull rod 79 and is anchored at its rear end 86 to a portion of the handle and at its forward end 87 to the pull rod (see Fig. 5). When the jack up is lowered, the spring 85 will be under tension. The spring has sufficient strength to move the pull rod 79 and slide member 83 and keep slack out of the flexible member '76, but the spring does not have sufiicient strength to elevate the lifting 5 members even when there is no load thereon. The operator can, at any time, grasp the handle 84 on slide 83 and pull the slide rearwardly along the handle, this pull being transmitted through flexible member '76 to swing the lever 11 upwardly 13 until the load is engaged by head 19. During this operation the pawls 44 and 49 will simply ride over the ratchet teeth of wheel 31. As soon as the load is engaged, the handle 84 is released and the remainder of the-lifting operation will be accomplished by swinging or oscillating the operating handle up and down, in the manner already described. During this additional lifting movement, the spring 85 will contract to keep the flexible member '76 taut.

It will be noted that the operations of this jack are controlled entirely from the handle, and that an operator positioned adjacent the rear end of the handle can manipulate the jack into position beneath the load, quickly raise the lifting head 1;; into engagement with the load, and then raise and lower the load, without changing his position. The jack is extremelycompact and has a minimum over-all height so that it may be manuevered into position beneath very low loads. It l-f' will be noted that the extreme height of the jack (adjacent the rear end of the carriage) is substantially no greater than the maximum width of the lifting lever 11, all of the operating mecha nism being housed in this vertical space between the upper and lower edges of the main lifting member. Furthermore, the end of the longer arm 1'7 of the lifting lever may be swung down so that the lifting head 19 may be positioned substantially no higher than the tops of the wheels 6 at the front end of the jack.

I claim:

1. In a lifting jack, a carriage, a load-lifting lever pivotally mounted in the carriage, there being an opening in the lever, an internal arcuate rack formed in the lever concentric with its pivotal axis, a shaft mounted in the carriage and projecting through the opening in the lever, a rotatable pinion carried by the shaft substantially in the plane of the lever and meshing with the rack, an oscillatable hand lever mounted in the carriage to swing about the axis of the shaft, and pawl and ratchet mechanism for imparting step by step rotation to the pinion in either direction as the handle is oscillated.

2. In a lifting jack, a carriage, a load-lifting lever pivotally mounted in the carriage, there being an opening in the lever, an internal arcuate rack formed in the lever concentric with its pivotal axis, a shaft mounted in the carriage and projecting through the opening in the lever, a rotatable pinion carried by the shaft substantially in the plane of the lever and meshing with the rack, an osciilatable hand lever mounted in the carriage to swing about the axis of the shaft, a ratchet wheel keyed to the pinion, a lifting pawl carried by the handlever and engaging the ratchet, a holding pawl mounted in the carriage and engaging the ratchet, springs for normally urging the pawls into engagement with the ratchet so that oscillation of the hand lever will impart step by step rotation to the pinion in one direction, a reversing mechanism adapted to engage the pawls to change the direction of rotation of the pinion, and means carried by the hand lever for positioning the reversing mechanism.

3. In a lifting jack, a carriage comprising a pair of spaced apart side frames, a lifting lever fulcrumed on a horizontal axis between the side frames, a load-supporting head carried at one end of the lever, an arcuate rack formed in the lever concentric with its pivotal axis, a horizontal shaft mounted between the side frames, a pinion carried by the shaft and meshing with the rack, an operating lever mounted in the carriage to swing about the axis of the shaft, and pawl and ratchet mechanism between the operating lever and pinion whereby swinging movement of the operating lever will impart step by step rotation to the pinion in one direction.

4. In a lifting jack, a carriage comprising a pair of spaced apart side frames, a lifting lever fulcrumed on a horizontal axis between the side frames, a load-supporting head carried at one end of the lever, an internal arcuate rack formed in the lever concentric with its pivotal axis, a horizontal shaft mounted between the side frames and projecting through an opening in the lever, a pinion carried by the shaft substantially in the vertical plane of the lever and meshing with the rack, an'operating lever pivotally mounted about the axis of the shaft for swinging movement, and pawl and ratchet mechanism between the operating lever and the pinion.

5. In a lifting jack, a carriage, a load-lifting member movably mounted in the carriage, an operating handle movably mounted in the carriage and projecting therefrom, operating mech-' anism between the handle and lifting member whereby movement of the handle will normally raise or lower the load-lifting member, a quicklift mechanism comprising a flexible member attached at one end to the load-lifting member, a

direction-changing device mounted in the carriage about which the flexible member is passed, and an operating member movably mounted on the handle to which the other end of the flexible member is attached.

6. In a lifting jack, a carriage, a load-lifting member movably mounted in the carriage, an operating handle movably mounted in the carriage and projecting therefrom, operating mechanism between the handle and lifting member whereby movement of the handle will normally raise or lower the load-lifting member, and a quick-lift mechanism comprising a flexible member attached at one end to the load-lifting member, a direction-changing device mounted in the carriage about which the flexible member is passed, a manually movable slide positioned on the handle and means connecting the slide with the other end of the flexible member, and a normally tensioned spring for tensioning the flexible member in all positions of the jack.

7. In a lifting jack, a carriage, a load-lifting lever pivotally mounted in the carriage, an operating handle pivotally mounted in the carriage and projecting therefrom, operating mechanism between the handle and lever whereby swinging movement of the handle will impart raising or lowering movements to the lifting lever, and a quick-lift mechanism comprising a flexible member connected to one arm of the lever, a direction changing device mounted in the carriage adjacent the pivotal axis of the handle about which the flexible member is passed and an operating member movably mounted on the handle to which the other end of the flexible member is connected.

8. In a lifting jack, a carriage, a load-lifting lever pivotally mounted in the carriage, an operating handle pivotally mounted in the carriage and projecting therefrom, operating mechanism between the handle and lever whereby swinging movement of the handle will impart raising or lowering movements to the lifting lever, and a quick-lift mechanism comprising a flexible member connected to one arm of the lever, a direction changing device mounted in the carriage adjacent the pivotal axis of the handle about which the flexible member is passed, a manually movable slide positioned on the handle, means connecting the slide and flexible member, and a spring associated with the last mentioned means for normally tensioning the flexible member in all positions of the jack.

9. In a lifting jack, an elevating and lowering mechanism comprising a ratchet wheel, an operating handle pivoted for swinging movement about the axis of the ratchet, an operating pawl pivoted on the handle, a spring for yieldingly urging the pawl into engagement with the ratchet, a holding pawl pivoted on a fixed axis, a spring for normally urging the holding pawl into engagement with the ratchet, a reversing member pivotally mounted about the axis of the ratchet and formed with cam fingers adapted to engage and move the pawls in certain positions of the reversing member, and a link mechanism connecting the reversing member with the handle and normally tending to swing the reversing" member with the handle, said link mechanism comprising a spring and means for tensioning the spring to actuate swinging movements of the reversing member independently of the handle movements.

10. In a lifting jack, an elevating and lowering mechanism comprising a ratchet wheel, an operating handle pivoted for swinging movement about the axis of the ratchet, an operating pawl pivoted on the handle, a spring for yieldingly urging the pawl into engagement with the ratchet, a holding pawl pivoted on a fixed axis, a spring for normally urging the holding pawl into engagement with the ratchet, a reversing member piv- WARREN H. WALKER.

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