US1413792A - Lifting jack - Google Patents

Description

S. SELDEN.

LIFTING JACK. APPLICATION FILED MAR. 2 2, 192!- 1,41 3,792, atented Apr. 25, 1922.

INVENTOR. 51/70:; 621.00%

ATTORNEY SAMUEL SELDEN, OF DENVER, COLORADO.

LIFTING- JACK.

Specification of Letters latent. Patente 1 Apr, 25, 1922,

Application filed March 22, 1921. Serial No. 454,363.

To all whom it may concern Be it known that I, SAMUEL SELDEN, a citizen of the United States, residing at Denver, in the county of Denver and State of Colorado, have invented certain new and useful Improvements in Lifting Jacks, of which the following is a specification.

This invention relates to lever jacks of the single action type and its primary ob-. ject is to provide in a jack of this character a reversing mechanism which combines, sim plicity, compactness and. durability of construction with practicability, efliciency and Convenience of operation.

l/Vith this object in view, my invention consists in the construction, arrangements and combinations of parts fully disclosed in the following description taken in connection with the accompanying drawings which illustrate an embodiment thereof.

In the drawings in' the several views of which like parts are similarly designated,

Figure 1 represents an elevation. of a single acting lifting jack to which myinvention is applied;

Figure 2, a vertical sectional elevation of the operating parts of the same showing my improved reversing mechanism in the position it occupies when the jack is used to lift its load;

Figure 3. a section taken on the line 3--3, Figure 2 Y Figure 4, a section similar to that of Figure 2 showing the reversing mechanism in the position it occupies whenthe' jack is used to lower its load, the two pawls which act upon the rack bar having been shown in the position in which the locking pawl is released from the rack-bar and the lifting pawl is in engagement with the teeth thereof prior to its being lowered by upward movement of the operating lever;

Figure 5, a view similar to Figure 4 show-, ing the parts in the position they occupy after the lever has completed its upward movement;

Figure 6, a side elevation of the eccentric adjusting member of the reversing mecha nism, and I Figure 7, a view similar to Figure 2 showing the adjusting member provided with an additional spring-member for forcing the lifting pawl into engagement with the teeth of the rack-bar when the jack is used for lifting its load.

Referring more specifically to .the drawings, the reference character 2 designates a f standard of conventional form and construction in which a rack-bar. 3 has a verticalsliding movement. A housin 4 on the standard in which the parts'of t e lifting. and reversing mechanism are cooperatively assembled is normally closed by a side plate 5 which is detachably fastened to the bodyof the standard by screws 6.

The lever of the jack consists asusual of a metal socket-7 which is fulcrumed on 7 the standard through the medium of a transverse pin 8 and a, wooden handle 9 which is fitted in the socket at the. outer end thereof.

The socket has as usual, two shoulders 10 and 12 to limit its movement in opposite directions by engagement with a corresponding part of thestandard and the retaining pawl hereinafter to be described, and it carries at its inner end the lifting pawl 13 '1 which normally engages with the teeth of the rack bar.

j The pawl 13 is pivotally supported at the end of the socket through the medium of trunnions 14 which extend in correspondingly formed open seats thereof and it is positioned with relation to the rack bar to constantly engage the teeth thereof by force of gravity.

Alocking or retaining pawl 15 which in the operationof the jack supports the load on the rack-bar while the other pawl is be-.

ing lowered is pivoted on the standard as at 16 to enter the teeth of the rack above the point at which the lifting pawl engages. The retaining pawl is likewise positioned with relation to the rack bar to engage the teeth thereof by gravity and when the lever is in a condition of rest, as illustrated in Figure 2 of the drawings, both pawls mesh with the teeth of the rack bar and thus cooperate to hold it in its adjusted position.

The reversing mechanism of the present invention comp-rises ablock 17 which by means of a laterally projecting pin 18 is slidably supported in a horizontal slot of a plate19 which is fastened inside the housing of the standard in substantial parallel relation to the before-mentioned closing plate 5.

An eccentric 20'rotatably mounted on the pin is held against displacement by a head 21 at the outer end of the sameland it has 7 forwardly projecting thumb wings 22 inside an opening 23 of the cover plate 5 to per- 7 parts lowered and nisin tenses the slanting surface as mit of its rotation for the purpose of sliding the blocl: in the slotof the plate.

Elie eccen'ric to this end works in a ring 24- which. at the end of a radially projecting arm 25 is pivotally mounted upon the plate 19. Pivotally connected on top of the slid iiig block is a dog 26 the downwardly extending head of which hasa slanting surface 2? which in the operation of the reversinp mechanism is engaged by a laterally projecting stud :28 on the 1"" Eng pawl, as will hereinafter more fully described.

The dog which normally rests upon the upper surface of the bloc; carries an. upwardly curving leaf-spring iit which when the reversing mechanism is in its operative position, cooperates with stud 30 at the upper end'of the retaining pawl and another leaf-spring '31 attached at the bottom surface of the block 1? is designed to engage with a'second stud 32 on the lifting pawl. L-oth springs extend forwardly from the with which they are coni'iected, with relation to the rack bar and the therewith engaging pan l's and the lower spring has a reversely bent end portion for its en gageinent with the respective stud 32 on the. lifting pawl when the jack is operated. to lower its load.

When the jack is used to lift the load, as illustrated in Figure 2 of the drawings, the sliding block is in its extreme forward position in which the dog resting upon its upper surface and the two springs are out of the paths of travel of-tlie respective studs 32, :28 and 34) on the two pawls.

'lVith the parts'thus positioned the down ward movement of the lever causes the rack to be raised through the medium of the lifting pawl while the lever is subsequently the pawl passes idly across the teeth of the rack, the latter is locked in its adjusted position by engagement with the retaining pawl.

it will thus be understood that the operation of the jacl as a medium the springs of the 'eversing mecl lllOPQllitlVG and gravity is only 'fOll'Q relied upon to effect the opera tive engagement of the pawl with the teeth of the rack bar.

' In order to revei is the movement of the raclt'bar for the purpose of lowering the load upon. its top, the slide by rotation of the eccentric moved'i'earvardly to the position illustrated in Figures -il and 5.

lVit-h the lever of the jack in its noinial position of rest the adjustment of the slide 5 of the ,liead of the pivoted dog to ride across the upper stud of the lifting: pawl. therein: moving the dog upwardly about its pivot until its during); lifti n ure el.

The upward motion of the dog causes the curved spring 29 to forcibly the stud of the retaining pawl, with the result that when by a slight downward movement of the operating lever the pawl is released from the weight of the load on the rack-bar, the deflected spring; under the law of restitution will cause the pawl to disengage the teeth of the and thereby permit of the bar being lowered with'the lifting pawl when the lever is subsequently raised.

During the downward movement of the pawl 13 its stud engages the reversely bent end portion 32% of the spring 31 while the dog gradually rcassumes its original position and thereby carries the from the stud on the upper pawl and when the lever reaches the end of itsupward stroke thesprin 31 gradually deflected by the engagement of the stud 32 will disenthe pawl from "er while the upper pawl now entirely thefrom the other spring falls into the same and downward n'iovenient of the lever the parts are restored to their original position and the aoove described operation is repeated.

ilt will thus be seen that during the lowerinp; action of the jack the two pawls alternatelysustain the load d are alternately released from the teeth of the rack bar by the automatic action of the resilient members of the reversing mechanism.

.ln the construction illustrated in Figure an additional spring member 35 isprovided preferably by extending); the spring below the sliding block of the reversing mechanism at its rear end and bending; first down wardly and then forwardly to engage the stud 39, of the lifting pawl when the reersiiig mechanism is in its inoperative condition.. I

.T he supplemental sprin 9; member pressing upon the pawl aids in maintaining); it in at easement with the teeth of the rack bar.

elaying thus described my improved reversing- .inechauisin in the most-convenient and practical form at present known to me,

vcrsing mechanism comprising an adjustahle member, means for its adjustment to a determinate position with relation to the iawis, and springs on said member normally press against spring away taming in its adjusted position, to alternate-1y lift them out of engagement with the teeth of the rack bar in the operation of the jack by movement of the lever.

i'2f In a lifting jack, the. combination of a rack-bar, a. lifting pawl and a retaining pawl engaging the teeth thereof, a lever in operative relation to the liftingpawl, and a reversing mechanism comprising an adj ustable'carrier, means for its adjustment to a determinate positionwith relation'to the pawls, I spring members on said carrier adapted to engage with the pawls when the carrier is'in its adjusted position, to alternately lift them out of engagement with the teeth of the rack bar in the operation of the jack by movement of the lever, and a spring member on the carrier which in the normal position. thereof, acts upon the lifting pawl to maintain it in engagement with the rack.

3. In a lifting jack, the combination of a rack-bar, a lifting pawl and a retaining pawl engaging the teeth thereof and having laterally projecting studs, a lever in operative relation to the lifting pawl, and a reversing mechanism comprising an adjustable member, means for its adjustment to a determinate position with relation to the pawls, and springs on said member normally disengaged from the studs and adapted to bear upon the same when the member is in its adjusted position, to alternately lift the pawls out of engagement with the teeth of the rack bar in the operation of the jack by movement of the lever.

4. In a lifting jack, the combination of a rack-bar, a lifting pawl and a retaining pawl engaging the teeth thereof, a lever in operative relation. to the lifting pawl, and a reversing mechanism comprising a slid'ably mounted member, means for its adjustment to a determinate position with relation to the pawls, and springs on said member adapted to engage with the pawls when the member is in its adjusted position, to alternately lift them out of engagement with the teeth of the rack-bar in the operation of the jack by movement of the lever.

In a lifting jack, the combination of a ra.cl -bar, a lifting pawl and a retaining pawl engaging the teeth thereof, a lever in operative relation to the lifting pawl, and a reversing mechanism comprising a slidingmember, means for its adjustment to adeterminate position relative to the rack, a pivoted dog on the block, disposed to be raised by engagement with the lifting pawl when the block is in its adjusted position, and springs on the dog and the member adapted to engage respectively with the. re-

pawl and the lifting pawl when the member is in its adjusted position, to alternately lift them out of engagement with the teeth of the rack in the operation of the jack by movement of the lever.

' ative relation to the lifting 6. In a lifting jack, the combination of a rack-bar, a lifting pawl and a retaining pawl engagingthe teeth thereof, a lever in operpawl, and a reversing mechanism comprising a sliding member, means for its adjustment to a determinate dog pivotally disposed on the member to be raised by engagement with thelifting pawl when the member is in its adjusted position, and springs on the dog and the member adapted to respectively engage the retaining pawl and thelifting pawl when the member is in-its adjusted position, to alternately lift them out of engagement with the teeth of the'rackbar in the operation of the jack by movement of the lever.

7. In a lifting'jack, the combination of a rack-bar, a lifting pawl and a retaining'pa'wl engaging the teeth thereof'and having later-,

ally projecting studs, a lever in operative relation to the lifting pawl, and a reversing mechanism comprising a sliding member, means for its adjustment to a determinate position with relation to the pawls, a dog pivotally disposed on the member to be lifted by engagement with the lifting pawl when the 'member is in its adjusted position, a spring on the dog which in the raised position thereof presses upon a stud on the retaining pawl, to release the latter from the teeth of the rack bar while the bar moves downwardly with the lifting pawl, and a spring on the member pressing upon the stud of the lifting pawl to release the latter from the teeth of the rack bar at the termination of its downward motion.

8. In a lifting jack, rack-bar, a lifting pawl and a retaining pawl engaging the teeth thereof, a lever in operative relation to the lifting pawl, and a reversing mechanism comprising a sliding member, means for its adjustment to a determinate position with relation to the pawls, a dog pivotally disposed on the member to be lifted by engagement with thelifting pawl when the member is in its adjusted position, a spring on the dog which in the raised position thereof presses upon the retaining pawl to release it from the teeth of the rack-bar while the bar moves downwardly with the lifting pawl, and a spring on the member pressing upon the lifting position relative to the pawls, a'

the combination of a pawl to release it from the teeth of the rack I bar at the termination of its downward motion.

9. In a single action lifting jack, the combination with a lifting pawl and a retaining pawl having laterally projecting studs, of a sliding member, means for adjusting it to a determinate position relative to the pawls, a pivoted dog on the member adapted to be raised by pawl, a spring a stud on the engagement with the lifting on the dog adapted to engage retaining pawl in the raised position of the dog, and a spring on the member extending in the path of a stud on the lifting pawl during downward movement thereof.

' 10. In a lifting jack, the combination of a rack bar, pawls engaging the teeth thereof, an operating lever, and a reversing mechanism comprising an adjustable member, means for its adjustment to a determinate position with relation to the pawls, and springs on said member normally disengaged from the pawls and adapted to engage with the pawls when the member is in its adjusted position, to alternately lift them out of engagement with the teeth of the rack bar in the operation of the jack by movement of the lever. p

11. Ina lifting jack, the combination of a rack bar, pawls engaging the teeth thereof, an operating lever, and a reversing mechanism comprising a slidably mounted member, means for its adjustment to a determinate position with relation to the pawls, and springs on said member adapted to engage with the pawls when the member is in its adjusted position, to alternately lift them out of engagement with the teeth of the rack-bar in the operation movement of the lever.

12. In a lifting jack the combination of a rack bar, pawl engaging the teeth thereof, an operating lever, and a reversing device including a sliding carrier and slanting springs on the carrier normally disengaged from the pawls and adapted to engage with the same in an adjusted position of the carrier.

In testimony whereof I have aflixed my signature.

SAMUEL SELDEN.

of the jack by a lifting pawl and a retaining

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