US312316A - barrett - Google Patents

Description

(No Model.) 4 I 2Sheets-Sheet 1Q J. BARRETT. LIFTING JACK.

No. 312,316. Patented P Y & a A (if 7017? ATTORNEY;

WITNESS S- W2 v 2 Sheets-Sheet' 21 J. BARRETT.

(No Model.)

LIFTING 110K.

WITNEEUSEQSW INVLE%R, QM 1.. w i g I BYMt ATTORNEY NITED STATES PATENT EErcE.

JOSIAH BARRETT, OF ALLEGHENY, PENNSYLVANIA, ASSIGNOR TO THE DUFF llIANUFAOTUR-ING COMPANY, '(LIMITED,) OF SAME PLACE.

LlFTlNG-JACK.-

SPECIFICATION forming part of Letters Patent No. 312,316, dated February 17, 1885.

Application filed January 2, 1885. (No model.)

To all whom it n-taty concern, .1

Be it known that I, JOSIAH BARRETT, a citizen of the United States, residing at Allegheny, in the county of Allegheny and State of Pennsylvania, have invented certain new and useful Improvements in Lifting-Jacks, of which the following is a specification, reference being had therein to the accompanying drawings.

Figure 1 is a View in side elevation of my improved lifting-jack, the cap-plate being removed to show the operation of the pawls and their connections. Figs. 2 and 3 are diagrammatic views showing the position and operation of the pawlsinlowering the lifting-bar. Fig. 4 is a detail view of one of the pawls on an enlarged scale. Fig. 5 shows amodified form of the tripping-plate. Figs. 6 and 7 are detail views of the tripping-plate and its operzo ating-eocentric. Fig. 8is atransverse section on the line :0 01;, Fig. 1. Figs. 9and 10 are detail views of the end of the operatinglever and one of its side plates. Fig. 11 is an enlarged View of the pivot-pin of the operating-lever.

My invention relates to an improvement in lifting-j acks, the object of said invention being to provide for a continuous movement of the lifting-bar, said movement either up or down being effected equally by both the upstroke 0 and downstroke of the operating-lever; and to this end my invention consists, in general terms, in the construction and combination of parts, all as more fully hereinafter described and. claimed.

The frame or stand 1 is formed'with alongitudinal rectangularly-shaped passage, 2, (see Fig. 8,) said passage being open on one edge for about two-thirds of the length of the stand. Within this passage is placed the lifting-bar o 3, provided at its lower endrwith a foot, 4., projecting through the opening in the side of the stand.

Along one edge of the stand 1 is formed the flange 5, which is provided near its lower 5 end with an abutment, 6, said abutment and flange forming a socket for the reception of the inner end of the operative lever 7. The inner end consists of a stem or shank, 8, curved on its under side, the upper side being shaped as shown in Fig. 9, the grooves a forming seats for the reception of the end of the pawls and the side plates, 9. (See Fig. 10.) These'side plates are provided at their rear end with a tongue or nib, 10, adapted to fitin a notch, 11, in the lever, and are secured to the sides of the stem by rivets passing through the holes 12 in the stem and side plates. In the center of each of the side plates is formed the hole 13, through which is passed the pivotpin 14, the ends of said pin restingin suitable 6o openings in the abutment 6 and flange 5, the end of the lever, with the side plates, being inserted in the socket between said flange and abutment. This pivot-pin is held in place by a nib, 15, formed on the pin, said nib, when the pin is inserted, passing through a groove, 16, in the wall of the opening in the abutment 6, and entering into a notch, 17, in one of the side plates, said groove and notch being in line with each other only when the lever is at the lower limit of its movement.

9n each side of the central opening, 13, in each of the side plates are formed the openings or holes 18 and 19, the opening 18 being, when the lever is at the lower limit of its stroke, a little above a horizontal plane pass ing through the center of the pivot-pin 14, and the opening 19 being a little to the left of a vertical plane passing through said pin when the lever is in the position abovestated. In these openings 18 and 19 are placed the ends of pivotal shafts 20 and 21, formed on the lower ends of the long and short pawls 22 and 23, said ends being inserted before the plates are riveted to the stem 8. These pawls are constructed and arranged to engage one above the other with the teeth 24, formed along one edge of the lifting-bar 3.

To form the seats a for the shafts 20 and 21, the stem 8 is cast or otherwise formed in the shape shown by full and dotted lines in Fig. 9. The side plates are secured in place in any suitable manner. Holes are then drilled through the ribs 1) and the body of the stem in line with the holes in the side plates and of a corresponding size. The side plates are then removed, and the top portion of the ribs 1), (shown in dotted lines,) surroundingthe holes, is milled away, leaving the stem as shown in full lines in Fig. 9. The seats thus formed will correspond exactly in size and location with the holes 18 and 19 in the side plates, thus providing a long and durable bearing for the ends of the pawls. The upper edges of the seats a will form stops to limit the movement of the pawls. These pawls are held in engagement with the teeth of the bar by spring-levers and 26, pivotally attached to the pawls a short distance above the trunnions by the screws 27.

Around the pivotal screws or bosses projected from the inner sides of the levers are placed the coiled springs 28, one end of each of said springs being inserted in lugs 29 on the inner sides of the levers, and the opposite ends engaginglugs 30 on the pawls 22 and 23. The upper end of the lever 25 is held against an abutment, 31, on the flange 5, and the projection 32, near the upper end of the lever 26, is held against the lever 25 by the springs 28; hence, as the upper ends of these levers are held stationary, as above stated, the tension of the springs causes the pawls, to which the levers are pivoted, to bear against the toothed bar. In moving the operating-lever up, the outer pawl, 22,will engage one of the teeth of the lifting-bar and cause the same to move up. During the same movement the inner pawl is caused to move down a distance equal to half a tooth, the bar being at the same time raised a corresponding distance by the pawl 22, and during the downward movement of the lever 7 the inner pawl will engage the teeth of the lifting-bar, and cause a further upward movement thereof, and the outer pawl will be moved down half a tooth to engage another tooth of the bar. To lower the liftingbar, the operation of these pawls is reversedi. e., the outer pawl is in engagement with the lifting-bar during the downward movement of the lever, and the inner pawl is in engagement during the upward stroke-and to effect this reversal it is necessary that the outer pawl should be held away from the teeth during the upstroke and the inner pawl during the downstroke. This reversal of normal operation is eflected by the tripping-plate 33, said plate being provided with lugs 34 and 35, having suitably-shaped cam-surfaces, adapted for engagement with the rounded lower ends of the levers 25 and 26. This plate is pivoted at its lower right-hand corner to the abutment 6, (see Fig. 1,) and the lower left-hand corner is supported by an eccentric, 36, fitting within a notch in said plate, said eccentric being mounted on a pin, 37, screwing into the stand 1. In the normal position of the eccentric (see Fig. 1) the plate 33 is held in such a position that the lugs 34 and 35 are at one side of the path of movement of the ends of the levers 25 and 23 during the up and down movements of the operating-lever; but when it is desired to lower the lifting-bar the eccentric 36 is turned, by means of the wings formed thereon, so as to move the plate upward and to the right, there-. by bringing the lugs 34 and 35 into the path of the levers 25 and 26. (See Figs. 2 and 3.) In Fig. 2 the lever 7 is at the lower limit of its movement, the lower end of the lever 25 is in engagement with the lug 34, thereby. pushing said end outward, and with it the outer pawl, 22, and the inner pawl is in engagement with the liftingbar'. Now, as the lever 7 is raised, the inner pawl being lowered, thereby lowering the bar 3, the lower end of the lever 26 strikes against the lug 35 and is forced outward thereby, and effects a corresponding inward movement of the upper end of said lever, thuscausingaconsiderabletensiontothe spring 28, the tendency of said tension being to force the lever and pawl outward. During this downward movement of the inner pawl the outer pawl, 22, is moving up, being held from engagement with the lifting-bar by the lug 34, against which the lower end of the lever 25 bears. The pawl 22 is held in this position until the lever 7 is near the upper limit of its stroke, when the lever 25 escapes from the lug 34, and the pawl is thrown into engagement with the bar 3. The further downward movement of the bar is arrested by this engagement with the outer pawl, and by the continuance of the motion of the lever to the end of its stroke the lower pawl is released from the weight of the lifting-bar by the lifting action of the outer pawl, and is free to move outward under the action of the spring 28. The inner pawl having been released, asabove stated, the operative lever is moved down, thus permitting ofa similar movement to the bar 3, and during this downward movement the lower end of the lever 25 engages the lug 34, causing a compression of the spring on said lever similar to that above described, and the lever 26 moves up along the lug 35 until near the end of the downward stroke, when thelever escapes from the lug, and the pawl 23 in turn engages the bar 3, and the pawl 22 is pulled away therefrom by its spring, which has been compressed by the engagement of the lever and lug, as above stated. Thus it will be seen that the springs 28 and levers 25 and 26 act when the lifting-bar is to be raised to force the pawls inward against said bar, and when the bar is lowered the springs and levers act to force the pawls outward, said contrary effects being produced by the press ure exerted at the opposite ends of the levers by the abutment 31 in the first instance acting in one direction, and by the lugs 34 and 35 in the other instance acting in the opposite direction.

In lieu of the pivotal tripping-plate 33 a sliding plate (see Fig. 5) may be used, said plate being provided with cam-lugs, and being mounted in suitable ways formed in a plate, 38, corresponding in size and shape to the flange 5, and forming a cover to the operative parts on the side of the stand opposite the flange, and being secured thereto by screws.

On the plate 38 is mounted an eccentric fitting in a notch in the sliding plate, and adapt ed to give a back-and-forth movement to the plate, as clearly shown in Fig. 5. The operation and function of this sliding plate are similar to that of the pivotal plate before described.

I claim herein as my invention 1. In a lifting-jack, a toothed lifting-bar, in combination with a pivotal lever, two pawls pivoted to said lever, one on each side of its fulcrum-pin, and spring-actuated levers pivoted to said pawls, and having their upper ends rigidly supported as against the action of their actuating-springs, substantially as set forth.

2. In a lifting-jack, a toothed lifting-bar, in combination with a pivoted operating-lever, pawls 22 and 23, spring-actuated levers 25 and 26,.pivoted to said pawls, and a stationary abutment, 31, adapted to support the upper ends of the levers as against the action of their actuating-springs, substantially as set forth.

3. In alifting-jaok, a lever having-its in-' ner end composed of a stem provided with curved seats, and of side plates having openings inline with such seats, in combination with pawls 22 and 23, having their pivotal shafts formed integral with their lower ends, said shafts being constructed to fit in the openings in the side plates and in the seats in the stem and have a firm bearing therein, substantially as set forth.

4. In a liftingjack, a toothed lifting-bar, in combination with a pivotal lever, two pawls pivoted to said lever, one on each side of fulcrum-pin, spring-actuated levers pivoted to said pawls, and having their lower ends rounded, as described, and a movable trippingplate having cam-lugs thereon, said lugs being adapted, in certain positions of the plate, to engage and shift the lower ends of the levers, substantialiy as set forth.

5. In a lifting-jack, a toothed lifting-bar, in combination with a pivotal lever, two pawls pivoted to said lever, one on each side of its fulcrum-pin, spring-actuated levers pivoted to said pawls, and a tripping-plate movable to and from the path of the lower ends of the spring-actuated levers, and adapted, in certain positions, to engage and shift said lower ends for the purpose of disengaging the pawls from the tooth-bar, substantially as set forth.

6. In a lifting-jack, a toothedlifting-bar, in combination with a pivotal lever, two pawls pivoted to said lever, one on each side of its pivotal point, spring-actuated levers pivoted to said pawls, a tripping-plate adapted to engage and shift the levers for the purpose of disengaging the pawls from the toothed bar, and an eccentric for moving said plate to and from the path of said spring-levers, substantially as set forth.

7. In a lifting-jack, a toothed lifting-bar, in combination with a pivoted operating-lever, two pawls pivoted to said lever, one on each side of its i'ulcrunrpin, and spring-actuated levers pivoted to said pawls, said levers being so arranged, as described, that when rigidly supported at their upper ends as against the action of their springs they will operate to hold the pawls against the lifting-bar, and when similarly supported at their lower ends they will cause the pawls to move away for the lifting-bar, substantially as setforth.

In testimony whereof I have hereunto set my hand.

"Jos ua BARRETT.

Witnesses:

DARWIN S. Worootr'r, R. H. WnITTLnsEY.

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