US2176715A - Lifting device - Google Patents

Description

@CL 17, 3939. A. 1 A .JoHNsoN 2,176,715

LIFTING DEVICE Filed may J5, 1937 1:1 E5. lef/L E i- 1,9

Patented Oct. 1.7, 1939 UNITED emr LIFTING DEVICE poration ofy Ohio Application May 6, 1937, Serial No. 141,141

Claims.

This invention relates to lifting jacks and more particularly to a lifting jack especially adapted for engagement with a bumper, bumper suppo-rt or like portion of the vehicle for elevating the 5 same.

The invention has for an object the provision of a lifting jack of a character wherein a relatively stationary thrust bar or rack carries a movable load engaging means and an operating mechanism.

An object of the invention is the provision of a lifting jack in which a toothed thrust bar slidably supports a load engaging element carried by a housing in which is mounted a dual pawl mechanism for elevating or lowering the housing and load engaging element along the thrust bar.

Further objects and advantages are within the scope of this invention such as relate to the arangement, operation and function of the rego lated elements of the structure, to various details of construction and to combinations of parts, elements per se, and to economies of manufacture and numerous other features as will be apparent from a consideration of the specification and g5 drawing of a form of the invention, which may be preferred, in which:

Figure l is a vertical elevational view of a lifting jack of my invention, the parts -being broken away for purposes of illustration;

Figure 2 is a fragmentary View showing a portion of the housing carrying the pawl mechanism;

Figure 3 is a view similar to Figure 2 showing the pawl mechanism in one position during the elevation of the housing and load engaging element;

Figure 4 is a view similar to Figure 3 showing the position of the pawl mechanism at one stage of the retraction of the housing and load eno gaging element;

Figure 5 is a view similar to Figure 4 showing another position of the pawl mechanism during the operation of retracting the housing and load engaging element;

Figure 6 is a View similar to Figure 4 showing one position of the pawl mechanism during retraction of the housing and load engaging structure;

Figure '7 is a View taken substantially on the line 7 1 of Figure 1;

Figure 8 is a detail sectional view taken substantially on the line 8--8 of Figure 4.

While I have shown the arrangement of my invention as particularly adapted for engagement with a bumper bar or other accessible portion of s ATENT the vehicle for the purpose of raising and lowering the latter, it is to be understood that I oontemplate the utilization of my invention in any place where force applying means may have utility.

Referring to the drawing in detail, the lifting jack is provided with a rectangular base member lil preferably formed of sheet metal and having a raised circular central portion ll forming a standard for supporting a thrust bar or rack it, the latter having a tenon portion l5 of reduced diameter projecting through an opening l@ in the elevated portion of the base member.

The tenen from the base member.

The thrust bar i4 is provided with a spiral thread 25 preferably of the buttress type that is, a thread in which the rod supporting face is perpendicular to the axis of the thrust bar while the back face makes an angle with the axis of the bar, the upper extremity of the thrust bar carrying a stop member or plate 26 secured to the thrust bar by swaging a tenon portion 2l of the thrust bar over the edges of an opening in the plate 26 which receives the tenon. The plate 255 is provided with a depending ear or stop member 1,

28 which prevents elevating the load engaging member beyond a predetermined point.

Slidably or movably mounted upon the thrust bar lli is a casing or carrier 3U formed of sheet metal.

The housing is preferably formed of substantially matched half sections 3l and 32 which are joined together by spot welding as at 33 or by other suitable means, the Sections of the housing being formed to provide a cylindrical guide 35, the housing sections also having spaced wall l portions which are secured together in spaced relation by means of shafts or pins 36, 3l and The guide portion 35 is of substantial longitudinal dimension to provide ample area for engagement with the periphery of the thrustl bar i4, the housing carrying at its upper end a load engaging arrangement which comprises a collar 39 having a ledge All to which is pivotally secured as at fil a hinged L-shaped bracket 42 having a laterally extending portion 43.

When the load engaging structure is brought into engagement with a load to be elevated, the bracket of the bumper or the bumper proper of the vehicle contacts with the laterally projecting ledge 43 causing the bracket 42 to pivot about the pin 4I to securely clamp the bracket 42 to the bumper bar or the like.

Fulcrumed upon the shaft or pin 38 is a lever or arm 45 preferably formed of two similar sections of sheet material, the extremities providing a socket portion 4l to receive an operating handle 48 which may be removably carried in the socket of the lever member. It is to be noted that the socket portion projects upwardly so as to place the operating handle in a more convenient position for manipulation in using the lifting jack.

Pivoted upon the shaft 38 is a pawl 50 hereinafter referred to as the retaining pawl and spaced from the fulcrum of the lever is a second pin or shaft 54 upon which is pivoted a pawl 55 hereinafter referred to as the lifting pawl. Bothv pawls are formed of sheet metal to substantially U-shaped ccnguration as illustrate-d in Figure 7, each having a suitably formed end portion 5l' and 58 respectively adapted for engagement with the teeth formed by the thread on the thrust bar I4. The portions 5'! and 58 are preferabl;7 rounded to conform to the cylindrical configuration of the thrust bar as shown in Figure '7, and thus provide a surface of substantial area of engagement of the pawls with the thrust bar.

A spring member 68 has a portion extending around the shaft 38, one end of the spring being hooked into an opening 52 in one side wall of the. retaining pawl 58, the other end of the spring being curled around a pin 53 which is slidably carried in a slot 64 contained in a side wall of section 32 of the housing or casing structure.. One side wall of the lifting pawl 55 is provided. with an opening into which projects a cotter key' S6 of usual construction, through the opening of which extends the intermediate portion of the. spring E8. In this manner the force of spring 69 influences the movement of the liftingpawl 55 and yet the spring is free to move longitudinally through the cotter key carried by the pawl- The pin 53 is provided with a manipulating button 58 positioned exteriorly of the housing forv controlling the action of the pawls in a manner' to be hereinafter explained. The shaft 31 connecting the sections of the housing also providesI a support for a member 58 to which is secured a resilient plate or platform l5, the latter during certain conditions of operation of the pawl mechanism adapted to engage the rear edge portions. of the lifting pawl 55.

The operation of the device is as follows: Referring particularly to Figures 1 and 3 through 6i inclusive, there are illustrated various stages orpositions of the pawl mechanism during the sequence of movements of the mechanism in. manipulating the jack. In Figures 1 and 3,. which illustrate positions of the mechanism during the elevation of the housing or carrier and. load engaging structure, and with the button ISISV in the up position as shown in Figures l and 2,. the lever member 46 being manipulated by handle- 48 as illustrated in Figure l, is shown in its. extreme counter-clockwise position of movement with the retaining pawl 50 in engagement with a tooth 25 of the thrust bar I4. With the lever in this position, the lifting pawl is in a position. to engage a tooth of the thrust bar I4 as the lifting pawl is urged toward the thrust bar by the spring 60 acting through the medium of the cotter key 66 carried by the lifting pawl. A clockwise oscillation or movement of the lever 45 about the fulcrum 38 moves the pivot pin 54 downwardly with the lever and as the extremity of the lifting pawl 55 is in engagement with a tooth of the thrust bar, the housing 38 and the load engaging structure carried thereby are elevated a distance of one tooth.

When the lever has been oscillated to its extreme clockwise position, as shown in Figure 3, the retaining pawl 58 being under the influence of the spring B8, is urged into engagement with a succeeding tooth in the thrust bar. Thus, when the lever is again moved in a counter-clockwise direction about its fulcrum, the retaining pawl 5D prevents the housing from moving downwardly along the thrust bar and when the lever has reached its uppermost counter-clockwise oscillation, the lifting pawl 55 is brought to a position to engage the next succeeding or higher tooth in the thrust bar I4, and repeated clockwise oscillation of the lever again elevates the housing through a distance of one tooth. This sequence of operation takes place until the load engaging element has elevated the load in engagement therewith to the desired position.

When it is desired to lower or retract the housing and load engaging structure, the manipulating button 58 is moved in the slot 54 in the housing wall to the down position as shown in ydbtted lines in Figure 2, which moves pin 83 to the position shown in Figures 4, 5 and 6, this movement of the manipulating button and pin 53 carrying one end of the spring t@ with it, changes the effect of the spring upon the pawls .so that with the manipulating button in the down position the spring tends to normally urge vboth the lifting and retaining pawls away from :engagement with the teeth in the thrust bar I4.

Referring particularly to Figure 5, the lever member 46 has been oscillated in a clockwise direction about its fulcrum 38 until the tip of the lifting pawl 55 has engaged with a tooth in the thrust bar I4 so that a further slight clockwise yoscillation or movement of the lever 46 places the vstress of the load upon the pawl 55. This move- :ment slightly elevates the housing, load engaging structure and load carried thereby, so that the stress of the load is relieved from the retaining pawl 56 and the latter is free under the influence of spring 6I) and is urged from engagement with .la tooth on the thrust bar. This position of the pawl mechanism is indicated in Figure 5. With the parts in this position, the lever member 45 through the handle 48 is swung in a clockwise `direction about its fulcrum 38, and as the lever moves counter-clockwise, the load being carried upon the lifting pawl 55, the housing, load engaging structure, and load are lowered a distance of one tooth of the thrust bar. As the housing is lowered and the lever moved counter-clockwise, the forward face 'I5 of the lifting pawl 55 acts as a cam and engages with the rear edge wall portion I6 of pawl 50 as particularly shown in Figure 6', thus camming the retaining pawl toward the thrust bar so that the retaining pawl is in a position to engage the next successive tooth .in the thrust bar when the lever hasrbeen moved valmost to its extreme position in counter-clockwise direction. A further slight counter-clockwise movement of the lever 46 taking place after the weight of the load has been shifted to the retaining pawl through its engagement with the tooth in the thrust bar leaves the lifting pawl free of the stress of the load and under the influence of spring 60 is moved out of engagementI with a tooth of the thrust bar as illustrated in Figure 4. A clockwise oscillation of the lever at this point in the operation moves the lifting pawl downwardly bringing its rear edge 11 into engagement with the platform spring l0 as shown in Figure 5, and the latter, opposing the resiliency of spring 60, cams in the lifting pawl toward the thrust bar and into engagement with the next successive tooth in the thrust bar. The above described sequence of operations is repeatedly continued until the load has been lowered and the load engaging element relieved from the stress of the load after which the jack may be removed from beneath the load.

It is apparent that within the scope of the invention, modifications and different arrangements may be made other than is herein disclosed, and the present disclosure is illustrative merely, the invention comprehending all variations thereof.

What I claim is:

1. A lifting device including a base member; a thrust bar carried by the base member; said thrust bar having a plurality of teeth formed therein; a casing structure rnovably carried on said thrust bar; a load engaging element carried by said casing; a lever fulcrumed upon said casing; a retaining pawl pivoted upon the fulcrum of said lever; a lifting pawl pivotally carried by said lever and spaced from the fulcrum of said lever; a spring interconnecting said pawls, said spring having a portion encircling the fulcrum of said lever; a manipulating means accessible exteriorly of said casing, one end of said spring being connected to said manipulating means whereby movement of the latter changes the action of said spring on said pawls,

2. A lifting device including a base member; a thrust bar removably secured to the base member; said thrust bar having a plurality of teeth formed therein; a casing structure rnovably carried on said thrust bar; a load engaging element carried by said casing; a lever fulcrumed uponr said casing; a retaining pawl pivoted upon the fulcrum of said lever; ak lifting pawl pivotally carried by said lever and spaced from the fulcrum of said lever; a wire like spring interconnecting said pawls, said spring encircling .the fulcrum of said lever; a manipulating button projecting eXteriorly of said casing, one end of said spring being connected to said manipulating button whereby movement of the latter changes the action of said spring on said pawls.

3. A lifting device including a base member; a thrust bar mounted upon the base member; said thrust bar having a plurality of teeth formed therein; a casing structure rnovably carried on said thrust bar; a load engaging element carried by said casing; a lever fulcrumed upon said casing; said lever being formed of substantially matched sections of sheet metal, said sections being secured together, portions of said sections being expanded to form a handle receiving socket; a pair of pawls associated with said lever; a spring interconnecting said pawls; a slot in a side wall of said casing; a control button slidably mounted in said slot, the end of said spring having connection with said control button whereby a change in position of the control button in said slot changes the action of said spring on said pawls.

Y 4. A lifting device including a base member; a thrust bar mounted upon the base member; said thrust bar having a plurality of teeth formed therein; a casing structure rnovably carried on said thrust bar; a load engaging element carried by said casing; a lever fulcrumed upon said casing; said lever being formed of substantially matched sections of sheet metal secured together, portions of said sections being formed to provide a handle receiving socket; a retaining pawl pivoted upon said lever fulcrum intermediate the side walls of said lever; a shaft carried by said lever and spaced from the fulcrum thereof; a lifting pawl pivotally supported upon said shaft; a spring having one end connected to the retaining pawl; a member having an opening carried by the lfiting pawl, said spring extending through the opening in said member carried by the lifting pawl whereby said pawl may move relative to said spring; and a control member connected to one end of said spring whereby a change in position of the control member changes the action of said spring on said lifting and retaining pawls.

6. A lifting device including a base member; a thrust bar removably secured to the base member; said thrust bar having a plurality of teeth formed therein; a casing structure rnovably carried on said thrust bar; a load engaging element carried by said casing; a lever fulcrumed upon said casing; said lever being formed of substantially matched sections of sheet metal secured together, portions of said sections being expanded to form a handle receiving socket; a retaining pawl pivoted upon said lever fulcrum intermediate the side Walls of said lever; a shaft carried by said lever and spaced from the fulcrum thereof; a lifting pawl pivotally supported upon said shaft; a spring having one end connected to the retaining pawl; a member having an opening carried by the lifting pawl, said spring extending through the opening in said member carried by the lifting pawl whereby said pawl may move relative to said spring; a slot in a side wall of said casing; a control button slidably mounted in said slot, the end of said spring having connection with said control button whereby a change in position of the control button in said slot changes the action of said spring on said lifting and re- 50 taining pawls,

ALVIN L. JOHNSON.

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