US2217403A

US2217403A - Jack

Info

Publication number: US2217403A
Application number: US246048A
Authority: US
Inventors: Earl G Gunn
Original assignee: Individual
Current assignee: Individual
Priority date: 1938-12-16
Filing date: 1938-12-16
Publication date: 1940-10-08
Anticipated expiration: 1957-10-08

Description

Oct. 8, 1940. GUNN 2,217,403.

JACK

Filed Dec. 16, 1938 -IIIIII Patented on. s, 1940 UNITED STATES PATENT OFFICE JACK Earl G. Gunn, Racine, Wis.

Application December 16, 1938, Serial No. 246,043

or similar mechanisms of the type in which the load-carrying element is frictionally held against movement relative to the supporting element One of the objects of my invention is to eliminate the danger in the present Jack" structures of this type, of the load getting out of control and dropping when the frictional hold is released.

A further object is to provide a means for releasing the frictional hold of the parts which is entirely controlled by the operator in a manner which automatically prevents the accidental and uncontrolled lowering of the weight of the load.

A further object is the provision 'of a simple but completely effective operator-controlled release means for Jacks of the friction holding type, whereby the operator cannot over-release the" device and cause the load to drop or fall unrestrictedly.

Other objects of my invention will appear from the accompanying drawing and the following description of the structure therein shown.

Fig. 1 is a view in elevation of a jack structure embodying my invention;

Fig. 2 is an enlarged vertical section of the operating mechanism of the structure shown in Fig. l, with its parts arranged for lifting or loadelevating purposes;

Fig. 3 is a view similar to said operating mechanism with the parts arranged for releasing or load-lowering purposes;

Fig. 4 is a transverse sectional view on the line 4-6 of Fig. 3; and

Fig. 5 is a transverse sectional view on the line 55 of Fig. 3.

My invention is applicable to any structure employing the principle of frictional gripping of one member for the purposes of moving and holding another member relatively thereto, but in order to illustrate the principle of my invention it is shown as being embodiedin a lifting jack commonly known as an automobile jack.

This jack has a column or standard i upon which a load-carrying member 2 is mounted to move lengthwise. The standard i is in the form of a cylindrical rod supported in vertical position in a foot or base member 3 having a socket 4 in which the end of the rod is inserted, these parts being readily separable for disassembly when the device is not in use. The load-carrying member 2 is in the form of an elongated sleeve freely movable along the rod and having at its upper end a suitably shaped member 5 to engage and carry the load to be raised or lowered, the load being represented by an automobile bumper M.

The load-carrying member 2 has at its lower portion a lateral extension i which bears upon one end of a holding member and which at the same time forms a pivot or fulcrum about which the holding member is movable. The holding member I is of the usual type in devices of this character and comprises a plate having a central opening a through which the rod standard I ex- 1 tends and an extension 9 forming the and upon which the load member extension 0 beers. Another and opposite extension II has an opening ll through which an operating link I! e!- tends.

The bore or opening 8 of the holding member is slightly larger in diameter than the diameter of the rod standard 5, so that when the holding member is canted or rotated about a horizontal axis with respect to the longitudinal axis of the rod I the edges 8a of the opening 8 frictionally grip the rod and thus hold the load at any height to which they are adjusted on the rod. A U- shaped spring l3, having one end in a socket bearing M of the load-carrying member 2 and its 25 other end bearing on the underside of the frictional holding plate extension 8, normally tends to urge and hold the frictional holding plate canted in a direction as shown in the drawing, so that the holding plate grips the rod and holds the load against downward movement but allows the load-carrying member and plate to move freely upwardly along the rod standard.

Power for lifting the load is applied to the loadcarrying member through the link i2 by means of an operating lever lb. The power arm of the lever is made in two sections. The short section l6 forms a socket into which the extension or handle ll of any desired length is inserted, this being the usual construction in devices of this character and so arranged that the handle i'l may be moved or replaced as desired.

The inner end of this lever is pivotally connected at l8 to the lower end of the link it. The upper end of the link is pivotally connected at 19 to the load-carrying member 2. The link i2, however, has an elongated slot 20 so that there will be some play in this pivotal connection for a purpose hereinafter described.

The operating lever I5 is pivotally mounted at H between upstanding lugs 22 on the end of another friction plate 23, similar to the holding plate I. This control plate is movable vertically on the rod standard i, and the edges of its openings through which the rod extends operates to u grip the rod when the plate is canted or rotated about a horizontal axis which, in the present structure, is the pivot 2|. This control plate, in accordance with my invention, is arranged to grip the rod in either direction of movement, depending upon the position into which the plate is canted. It is yieldingly held in either of these positions by means of the spring 24 which is carried by the rock shaft 25 mounted in the control plate 23. The rock shaft 25 has an operating arm 26 by which it can be rotated. It is held in either position by the spring button 21. In either position of the spring, one end bears yieldingly against the rod standard and holds the control plate 23 in its corresponding position. For instance, in Fig. 2, the parts are adjusted so that the control plate 23 is canted to a position which causes the plate to frictionally grip the rod and hold it against downward movement. This is the position in which the jack operates to raise the load; that is, when the lever I5 is swung downward about its pivot 2 I, power is transmitted through the link I2 and the pivotal connection I9 to the load-carrying member 2, which, together with the load, is moved upwardly on the rod. As soon as the lifting force is relieved by swinging the operating lever I5 upwardly, the holding plate I frictionally grips the rod and holds the load sustained in that position. The upward movement of the operating lever raises the control plate member 23 on the rod and upon reverse movement .of the operating lever the member grips the rod in that position.

In jacks ,of this character, it is the practice to utilize the removable handle I! for releasing the holding plate and allowing the load to lower.

This is done by providing a socket member into which the end of the operating handle I! is inserted and the parts are so arranged that movement of this hand lever then acts to pivot downwardly on the holding plate I to release its frictional grip upon the rod I. This allows the load to move downwardly until the releasing pressure on the plate I is removed. Since the handle I1, however, is in effect carried by the load-carrying member, it moves downwardly therewith and thus the operator has no accurate control of the release. The result is that frequently the loadcarrying member will accidentally drop the entire length of the rod and become very dangerous.

In accordance with my invention, I provide means for releasing the holding plate 2 independently of its relation to the load-carrying member. As before mentioned, the link I2 has some play in its pivotal connection I9 with the load-carrying member due to the elongated slot 20. The link also has a laterally extending lug 28 which bears upon the upper side of the extension of the plate I, as shown clearly in Fig. 3.

Thus when the link I2 is moved downwardly by the operating lever, the lug 28 e'xerts pressure downwardly on the end of the holding member 1 and rotates it in the reverse direction, causing the holding member 1 to release its frictional grip upon the standard and allow the load and said plate to move downward. This releasing pressure or action of the lug 28 upon the holding plate! continues only so long as the lug. 28 follows the plate I downwardly and continues to exert releasing pressure thereon. The instant, however, the downward movement of the lug 28 is stopped by stopping the movement of the operating lug, the holding plate moves downwardly away from said lug until the pressure is released.

The spring I3 then acts to again rotate the holding plate in the direction which causes it to again grip the standard and hold the load-carrying member in that position against further downward movement. This downward releasing movement of the link I2 and its lug 28 is entirely independent of the load-carrying member because of the slotted pivotal connection of the link with the pivot I9. Thus the load-carrying member can move downwardly only so long as the lug 28 exerts releasing pressure upon the holding member I, and the instant this pressure stops, the weight on the load-carrying member, together with the spring I3, automatically restores the holding member I to its holding position.

In Fig. 3 it will be noted that the control member 23 is in the reverse position to that which is shown in Fig. 2. In this position the member grips the rod standard I to hold said member against movement upwardly on the rod, thus holding the pivot 2I of the operating lever stationary so that the movement upwardly of the operating lever can exert a downward pull on the link I2 for releasing the holding member I. It will be thus further noted that when the parts are in the relation shown in Fig. 2, the reciproeating movement of the operating lever raises the load upwardly on the standard I in a step-bystep movement; that is, downward movement of the operating lever handle I! raises the link I2 and through its pivotal connection I9 raises the load-carrying member 2 a corresponding distance upwardly on the standard. The holding member then acts to hold the load-carrying member in that position while the operating lever handle is swung upwardly.

It i obvious that changes may be made in the construction, arrangement, and operation of the various parts, without departing from the spirit I member for releasing the engagement of the holding member with the standard.

2. In a jack of the class described, the combination of a standard, a load-carrying member movable on said standard, a friction holding member associated with said load-carrying member and arranged to grip the standard and hold the load-carrying member in any position to which it is moved on the standard, a friction control plate movable on said standard adjustable to grip the standard and hold itself against movement in either direction, an operating lever pivotally supported on said control plate and having means for applying power to said loadcarrying member, and means associated with said lever and acting upon said friction holding member for releasing the holding member.

3. In a jack of the class described, the combination of a standard, a load-carrying member movable on said standard, a friction holding member associated with said load-carrying member and arranged to grip the standard and hold the load-carrying member in any position to which it is adjusted on the standard, a friction control member movable on said standard adjustable to grip the standard and hold itself against movement in either direction, an operating lever pivotally mounted on said control member and having a link member for applying power to said load-carrying member, said link member being arranged to act upon said friction holding member for releasing the holding member, and means for adjusting said control member to grip the standard in accordance with the direction of movement of the load-carrying member on said standard, I

4. In a jack of the class described, the combination of a standard, a frictional holding member and a frictional control member mounted on said standard and each adapted to grip the standard to hold said members against movement, a load-carrying member supported by the holding member, an operating lever pivotally mounted on said control member and having means associated therewith for moving the loadcarrying member upwardly on said standard, said means being operable by said operating lever for releasing the holding member to' lower said load-carrying member on the standard, and means for adjusting the control member to hold it against movement in either direction depending upon the direction of movement of the loadcarrying member.

5. In a jack of the class described, the combination of a standard, a load-carrying member movable thereon and having associated therewith a. holding member adapted to frictionally grip the standard to hold the load-carrying member against movement in a downward direction when the holding member is canted in one direction, an operating lever mechanism independently supported on said standard, and having means for transmitting power to said load-carrying member for raising the load-carrying member on the standard, and means operated by said lever for canting the friction holding member in the reverse direction to release its gripping action upon the standard and permit the load-carrying member to move downwardly on the standard.

6. In a jack of the class described, the combination of a standard, a load-carrying member movable thereon and having associated therewith a holding member adapted to frictionally grip the standard to hold the load-carrying member against movement in a downward direction when the holding member is canted in one direction, a control lever supported on the standard independently of the load-carrying member, and means actuated by said control lever for canting said holding member in the reverse direction to release its grip upon the standard.

'7. In a jack of the class described, the combination of a standard, a load carrying member movable thereon and having associated therewith a frictional holding member adapted to grip the standard to hold the load carrying member against movement in a downward direction, a

frictional gripping member on said standard,

means for adjusting said gripping member to frictionally hold the gripping member against movement in either direction, an operating lever pivotally mounted on said gripping member, and a link connected with said lever and. engaging the load carrying member to transmit power thereto in an upward direction and having means to engage and release the frictional holding member in a downward direction.

EARL G. GUNN.