US812580A - Lifting-jack. - Google Patents

Description

PATENTED FEB. 13, 1906 H. M. MARSH, LIPTING JACK. APPLICATION FILED 001:. 4, 1905.

' UNTTE HUGH M. MARSH, OF GHICAGU, ILLINOIS.

LiFTme-dAoK.

Application filed October 4, 1905- Serial NO- 281,306-

following is a specification, and which are illustrated in the .accompanying drawings,

forming a part thereof.

The invention relates to a lifting-jack of that type in which a lifting-bar which slides in a suitable standard is operated from an ac tuating-lever by means of a ratchet-and-pawl mechanism, and particularly to such a jack which may be employed for lowering as well as raising a load. In devices of this kind there are usually provided two pawls, one of them pivotally secured to the actuating-lever and the other, a retaining-pawl, pivotally secured to the base or standard of the device, and means are provided for controlling the movement of the pawls into and out of engagement with the ratchet-teetlrof the lift ing-bar to obtain the required movement. As heretorore constructed, however, the mechanism employed for moving the pawls into and out oi engagement with the ratchet-bar when the device is to be used for lowering a load has included mechanically-operated parts between which there is considerable friction and which when worn by use do not move the pawls completely into engagement with the ratchet-teeth, and the operation of the device is unreliable.

The object of the present invention is to provide a jack of the type described in which ing operations, and in certian details of con.

struction, all as to be hereinafter described and claimed and as illustrated in the accom panying drawings, in which- Figure 1 is a side elevation of my improved lifting-jack, a part of the outer casing being removed to show the interior construction. Fig. 2 is a side elevation of the device with the casing intact.' Fig. 3 is a view similar to Specification of Letters Patent.

Patented Feb. 13, 1906.

Fig. 1, but showing the parts in a different position. Fig. 4 is a sectional view taken on the line 4 4 of Fig. 3; and Fig. 5 is a detail of the device, shown in. perspective.

A standard is provided for the device and is of ordinary construction, preferably having a broad base 11 to take a substantial bearing upon the ground. ratchet-bar 12 slides within the standard 10 and is provided with ratchet-teeth 13, formed upon 'one of its sides for substantially the whole of its length. The upper portion of the standard 10 is extended at one side, as indicated at 14, to provide a suitable support for the moving parts of the device and an in terior chamber 15, which is normally closed by a cover-plate 16, removably attached to the standard by means of screws 17.

An actuating-lever 18 reaches into the chamber and is pivotally secured to the walls of the standard at 19. The outer end of this lever is formed into a tapered socket 20 for receiving a wooden bar 21, such as usually accompanies devices of this kind. A pawl 22 is pivotally attached to the inner end of the actuating-lever 18 for en aging the ratchet-teeth 13, and there is also provided the usual retaining-pawl 23, this pawl being pivotally attached to the Walls 14 of the chamber 15 at 24 and shown as engaging the ratchet-teeth 13 above the point of engagement of the pawl 22.

A spring-rod 25 is provided for controlling the movement of the pawls into and out of engagement with the ratchet-teeth 13. As shown, it is of a V shape, having a coil 26 of one or more turns formed at the point of the \l to increase its flexibility and having overturned ends 27 and 28 for engaging the pawls.

mounted on that pawl, as 23, upon which the bearing-block slides, and projecting through a slotted aperture 32 in the cover-plate 16. A link 33 joins the bearing-block and the A lifting-post or turn-button, thedisposition of the parts being such that either of the extreme positions of .the bearing-block is self-sustaining. As

' shown, astop 34, projecting from the face of 13 of the lifting-post when the lever 18 is in the raiscdposition, as shown. It, now, the lever 18 is thrown down to raise the lifting-- bar, the arms of the spring are spread be yond their normal position as the pawl 22 rises, and when the limit of this movement I has'hee'n reached the spring will be so extend edto draw the retaining-pawl 23 into engagei'nent' with the ratchet-teeth 13 to support the load, while the lever 18 is again raised to the position shown in Fig. 1 to lower the pawl 22 for a new hold upon the liitiitg pOst. If, however, the turn-buttmi 31 is r tated to throw the bearing blocli 29 to its extremeupper position, as in Fig. 3, the arms of the spring 25will be separated when the lifting-pawl 22 is down. more than they would normally rest, and thus draw this pawl out of engagement with the ratchetteeth 13. The lever 18 may now be moved down to raise the pawl 22 without raising the liftingdiar. Just before the pawl 22 reaches the limit of its upward movement, however, the spring 25 becomes compressed and urges the pawls apart. The pawl 22 being free moves into engagement with the ratchet-bar, and its continued u ward movement raises the bar enough to re ease the pawl 23, which is then forced back by the spring, so that the load mfay descend with the pawl 22. The effect of the spring is again reversed just be fore the pawl 22 reaches the limit of its downward movement, and the retainingpawl 23 being free is easily drawn. into engagement with the ratchet-bar to support the load, after which the pawl 22 is immediately released by its continued dowi'iwardmovernent and is drawn back by the spring, so that it may he raised for a new hold upon the ratchetdmr, as before, without raising the bar. It will. he observed that the position of the pivot 24 of the pawl 23 is such that this pawl never comes into a vertical position, so that it is always urged by gravity'into engagement with the ratchet-bar and would support the load if the spring 25 should break at any time.

I'claim-as my-invention- 1. In alifting-j ack, in combination, a standard, a lever pivoted to the standard, aratchetbar in sliding engagement with the standard,

bar in sliding engagement with the standard,"

a pawl pivoted to the lever, a pawl pivoted to the standard, a spring having one end attached to each pawl, and-means for shifting the point of attachment of the spring on one of the pawls. 1

3. In a lifting-j ack, in combination, a standard, alever pivoted to the standard, aratchetbar in sliding engagement with the standard, a pawl pivoted to the lever, a pawl pivoted to the standard, a pivot-block in sliding engagement with one of the pawls, a spring pivotallp attached to the block and to the other paw and means for securing the block in an ad justed position on'the pawl. I

4. In alift ingjaek, in combination, a stand ard, alever pivoted to the standard, aratchetbar in sliding engagement with the standard,

a pawl pivoted to the lever, a pawl pivoted to' the standard, a pivot-block in sliding engagement with the last-named pawl, a s ring pivotally attached to the block and to he other pawl, and means for securing the block in an adjusted position on the pawl.

5. In a lifting-j ack, in combination, a standard, alever pivoted to the standard, aratchetbar in sliding engagement with the standard, a pawl pivoted to the lever, a pawl pivoted tn the standard, a pivot-block in sliding engagement with one of the pawls, a turn-button pivoted to the pawl, a link connecting the turn-button and the block, and a spring pivotally attached to the block and to the other pawl.

6. In a lifting-j aelr, in combination, a standard, a ratchet reciprocating in the standard, a.

pair of pawls, a lever carrying one (if the pawls, and a spring reacting between the two pawls and arranged to reverse its action as the lever approaches the limitsofits move ment.

noon. M. MARSH.

Witnesses CHARLES B. GILLsoN, E. M. KLAronER.

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