USRE4971E - wesion - Google Patents

Description

. T. A. WESTON.

Improvement in Differential! Pulleys.

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T. A. WESTON. lrnprvement'in Diffe'entifal Pulleys.

Reissued July 9, 18721.

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U1\irr rE:nV STATES PATENT i CDEEroE.

THOMAS ALDEIDGE WESTON, or RiDeEwoon, NEW JERSEY.

iMPRovEMENT iN DIFFERENTIAL PuLLEvs.

Specification forming part of Letters Patent No. 67,470, dated August (i, 1867; reissue No. 4,971, dated July 9,

To all whom it may concern:

Be it known that I, THOMAS ALnninGE WESTON, engineer, of Ridgewood, Bergen county-*,NewJe-rsey, have invented certain new and useful Improvements in Differential Pulleys, of which the following is a specification:

' engaging with the chain-links more efectively than by the means proposed prior-to my invention; secondly, in combining with the lsaid differential sheave a new safetydevice or keepers for preventing the accidental disengagement of the chain-links from the dilerential sheavc; thirdly, in making the differential.

sheave with more than two sets, consisting of peripheries differing in diameter, to give varions speeds in lifting; fourthly, in combining the aforesaid parts with an endless chain in a suitable frame.

In the accompanying drawing, Figure l, Sheet l, is a perspective view of the dii'eren.- tial sheave with its rims formed according to my invention and the course ofthe cha-in shown in dotted lines. Fig. 2- is an endv elevation of the frame for supporting the saiddifferential sheave, showing'also the safety device or keepers E E. Fig. 3 is a vertical section-of the differential sheave through its larger diameter, Fig. 4 being an edge view and Fig. 5 a side view of the same. Fig. 6 is a side view of my improved differenti al pulley complete, and Fi g. 7 is anv edge view ofthe same with the course of the chain shown in dotted lines. Y Fig. 8 is a section of a roller or rollers and shaft, which may be used instead of the stationary keepers in' Fig. '2 to prevent thediseng'agement ofthe chain-links from the differential sheave. Fig.

ent Oflice' with myoriginal application. Fig. 1'0 is a vertical section ofthe dili'erent-ial sheave jthrough its smaller diameter at the dotted line in Fig. 11, which latter is an edge view; and both figures are drawn in exact conformity with the aforesaid model, and to an enlarged scale for the better illustration of my improved mode of forming theperipheries or rims. Figs. 12 and 13 represent the plain grooved sheave placed in either loop ofthe chain in connection' with a suitable frame and hook, as shown in Fig. 9. y

The endless chain is applied as shown in Fig. 1--tl1atis to say, it is coiled twice around the dii'erential sheave, forming twodependin g loops, each loop having its two sides hanging, respectively, from the larger and smaller peripheries on opposite sides of the axis. The action is as follows: By rotating the differential sheave in the direction of the arrows in Fig. l the larger periphery d at each revolution takes up a length of chain equal to its circumferencefrom-the loop c, thesa-id loop receiving simultaneously a length of chain equal to the. lesser circumference 'of the periphery b. The loop c, thus receiving less chain per revolution than is taken from it, is gradually shortcned, causing the` bight to ascend together with the plain pulley suspended therein, and any attached load. The other loop,.d, is mean time equally lengthened by receiving at each revolution more chain overthe larger periphery a than is simultaneously taken from it over the smaller one, b, and by rotating the diiierential sheave in an opposite direction the motion of the loops is reversed. This differential action of the said sheave upon the chain and the resultant gain of power would be lost if the chain could slip over the peripheries of the sheave-that is, unless the portions of chain in contact with the said sheave were securely` treme precision over and onto the poin ts of the pins, and even then the engagement is uncertain from the constant tendency of the chain -loadedor strained on one side only-to ride clear oi' the points ofthe pins, and such pins, projecting unsupported from the face of the sheave, are also liable to` injury by bending or otherwise.

To obviate these defects I mold each face or periphery of the differential sheave with a deep central groove, l, and on either side of it recessed flanges n u 'and webs o o. Those links which present themselves edgewise to the differential sheave are received into the groove l; the intermediate links, presenting themselves flatwise to the sheave, are guided by the flanges 'n and webs o down into the recesses thus formed, Where the said links are securely held, being shrouded in the solid metal ofthe she-ave.

Therecessed anges and webs diverge from v each other, opening Wider outwardly, so that when the position ofthe operator or ofthe load requires it the chain can approach and leave the differential sheave obliquely. By this conformation of the peripheries the necessity of using the Weak and exposed pins or spikes is obviated, and a secure, durable, and free Working engagement between the chain and differential sheave is obtained Without complexity of structure.

In order to render the accidental disen gage` ment ofthe chain-links impossible I employ a double roller, Fig. 8, beneath which the links V can only pass when embedded securely Within the cells or spaces provided for them inthe rims of the differential sheave or, as an equivthe rigid keepers E may be lixed to each other as to form, in eiect, a sin-l gle piece.

Having described my invention, I would state that I do not eonline myself to the pre#l cise details herein described, as the same may be varied without 'departing from the nature of my invention; but

l. A diierential sheave, consisting of ltwo or more united sheaves of dissimilar diameters,

having their peripheries provided with a deep central groove, Z, recessed flanges n n, and

webs o o for gearing the said differential sheave to a chain, substantially as specified. l 2. The safety-roller or equivalent fixed keepers, in combination with the said diiercntial sheave, as and for the purposes set forth.

3.- The aforesaid dili'erential sheave, constructed as described, in combination with an endless chain and a supporting-frame, substantially in the manner set forth.

y THOMAS ALDRIUH WESTON. y

Witnesses:

' J. FRASER,

CHARLES M. HIGGINS.

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