US758903A - Lifting-jack. - Google Patents

Description

No. 758,903. PATENTED MAY 3, 1904. D. DONALD.

LIPTING JACK.

APPLICATION FILED APR. 9. 1903.

UNITED STATES Patented May 3, 1904.

PATEN '1 OFFICE.

LIFTlNG-JACK.

SPECIFICATION forming part of Letters Patent No. 7 58,903, dated May 3, 1904.

Application filed rpril 9, 1903. Serial No. 151,710. (No model.)

To all whom it 71mg concern.-

Be it known that I, DONALD DONALD, a citizen of New Zealand, and a resident of Masterton, New Zealand, have invented certain new and useful Improvements in Lifting-Jacks, of which the following is a specification.

This invention relates to improvements in lifting-jacks of that class in which a ratchetfaced lifting-bar is mounted to slide vertically within a standard and is given a step by-step motion up or down, as desired, by a pair of pawls mounted upon an oscillating fulcrum and serving to engage successive teeth of the bar in alternation as the fulcrum is oscillated. The object of the invention is to provide an improved construction in devices of this character; and it consists of the matters hereinafter set forth, and particularly pointed out in the appended claims.

In the accompanying drawings, Figure 1 is a rear edge elevation of a jack constructed in accordance with my improvement. Fig. 2 is a side elevation thereof. Fig. 3 is an enlarged sectional detail of the operative parts of the mechanism, taken on line 3 3 of Fig. A. Fig. 4 is an enlarged sectional detail taken on line 4 4 of Fig. 3. Fig. 5 is a perspective view of the oscillating fulcrum alone, parts being broken away. Fig. 6 is a sectional detail taken on line 6 6 of Fig. 2. Fig. 7 is a sectional detail showing the manner in which the pawl-pivots are secured within the oscillating fulcrum. Fig. 8 is a perspective detail of the outside pawl.

In said drawings, A designates the jackframe or standard, and B the toothed liftingbar, which slides vertically on said standard. As herein shown, the lifting bar passes through a housing A, formed at the upper end of the standard, and is itself provided at its lower end with prongs 7), which embrace ribs (1, that extend vertically up the front edges of the standard on each side from its base A to the housing A. Openings (1, cut

through the ribs 7/ above the base, enable the prongs of the lifting-bar to be passed in behind the ribs a these openings being afterward preferably and desirably filled by wedges a", driven in from the inner sides of the ribs.

The housing A is bored out in front of the lifting-bar to receive the oscillating fulcrum C, which carries the pawls D and E. This oscillating fulcrum is essentially a cylindric part cut away at its upper middle portion to a depth of something more than half the diameter of the cylinder, Fig. 5. This leaves at its ends completely circular disk portions 0, connected below by an integral part c, the lower surface of which is cylindric and coincides with the exterior of the end disks, forming therewith the bearing-surface of the fulcrum. This fulcrum extends entirely through the housing and is provided at one end with a polygonal projecting lug c", to which the operating-handle O of the jack is applied, like an ordinary socket-wrench. Radially-projccting lugs c on the outer faces of the ends of the fulcrum serve to loosely embrace the outside of the housing and hold the fulcrum against endwise movement with reference thereto. These lugs are admitted when the fulcrum is originally inserted through apertures a, opening into the bore, which receives the fulcrum. The apertures (1 are provided in a different angular position from that which is occupied by the lugs after the machine is assembled, and the fulcrum is inserted by turning it so thatits lugs 0 will come in line with and pass through the apertures-c and by then turning it back within the housing to bring its bearing-face lowermost. This carries the lugs 0 out of alinement with the extensionopenings (4 even du ring the most extreme normal oscillation of the fulcrum, and thus prevents their slipping back through the extension-openings except by intention.

The pawls D and E are carried upon hardened-steel pins F and F in holes bored in the end disk portions 0 of the fulcrum and span, as it were, its cut-away upper middle portion. Such pins are further supported midway between their ends by bearings 0", formed on the cut-away upper side of the connecting portion 0 of the fulcrum, the lower ends of the pawls being bifurcated, as shown in Fig. 8. so as to span the bearing-lugs thus provided. To retain the pins F and F in place, the holes which receive them are bored clear through the end disk 0 of the fulcrum at one end, as shown at (1, but are only bored part way through in the disk 0 at the other end, as shown in Figs. 5 and 7. The pin is then thrust entirely through the hole 0 and through the hole in the pawl until it enters and is firmly seated in the hole 0, whereupon the metal around which the edge of the hole at 0 is jammed in, so as to prevent the pin from sliding out under ordinary circumstances. A small aperture 0 extending through the end disk of the fulcrum from the socket 0 then enables a punch to be inserted for the purpose of driving the pin out whenever it is desirable to remove the pawls.

An important feature of the present improvement consists in mounting the pin F, which supports the inner pawl D, at a greater distance from the axis of the oscillating fulcrum than is the pin F, which supports the outer pawl E, Fig. 3. This results in increasing the effective movement of the load during the downstroke, when the weight of the operators body can be applied to the operatinghandle, and correspondingly of relatively increasing the leverage during the upstroke, when the handle must be lifted by main strength. The difference existing in the device here illustrated is about as five is to three; but this may obviously be varied as desired and according to the particular class of work for which the machine is intended.

The operation of my improved jack in lifting a load requires simply that the lever-handle be oscillated, whereupon each pawl will take hold of the toothed barin succession as it rises and will drag idly over its teeth as it descends, thus gradually forcing the bar up to the limit of its movement. In lowering the load the gravity of the pawls is overcome by taking hold of them with one hand, while the lever is oscillated with the other. To this end the inner pawl D is provided on each side with lugs (Z, which project inwardly past the toothed edge of the bar on either side and not only form finger-pieces, but serve as weights to insure the engagement of the pawl with the bar by gravity, while the outer pawl E is provided at its upper end with a projecting ear 6, which can conveniently be grasped by the thumb, while one of the finger-pieces e of the inner pawl is caught by the fingers.

I claim as my invention- 1. A lifting-jack comprising a standard, a toothed bar having a sliding engagement with said standard, and a pair of pawls mounted on an oscillating fulcrum and acting upon the toothed bar in alternation, the pivotal points of said pawls being at different distances from the oscillatory axis of the fulcrum, substantially as described.

2. A lifting-jack comprising a standard, a toothed bar having a sliding engagement with said standard, and a pair of pawls mounted on an oscillating fulcrum and acting upon the toothed bar in alternation, the pivotal point of the inner pawl being at a greater distance from the oscillatory axis of the fulcrum than the pivotal point of the outer pawl, substantially as described. 7

3. A lifting-jack comprising a standard, a toothed bar having sliding engagement with said standard, an oscillatory fulcrum mounted in the standard, and a pair of pawls pivoted to said fulcrum and acting upon the toothed bar in alternation, said fulcrum comprising cylindric end disks connected below by an intermediate part, pivot pins for the pawls mounted in apertures in said end disks, and bearing lugs on the integral connecting part for the middle of said pin, substantially as de-. scribed.

4. A lifting-jack comprising a standard, a toothed bar having sliding engagement with said standard, an oscillatory fulcrum inserted through a bore in the standard, and a pair of pawls pivoted to said fulcrum and acting upon the toothed bar in alternation, said fulcrum being provided at its ends with lugs embracing the sides of the standards to prevent endwise movement of the fulcrum, and said standard being provided with apertures at the edge of its fulcrum-receiving bore for admitting said radial lugs,'substantially as described.

In testimony that I claim the foregoing as my invention I aflix my signature, in presence of two subscribing witnesses, this 7th day of April, A. D. 1903.

DONALD DONALD. Witnesses:

HENRY W. CARTER, R. A. Cos'rELLo.

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