US 893032 A
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Description (OCR text may contain errors)
. PATENTED JULY 14, 1908.
- E. B. SWEET.
APPLICATION FILED JAN. 11, 190B.
2 SHEETS-SHBET 1 llllllll I' l W21 tn esse PATENTED' JULY 14, 1908.
E. E. SWEET. WORM GEARING. APPLICATION FILED JAN.11, 1908 2 SHEETS-SHEET 2.
7 WI fn ess es 7 lm e'n for I 5m estE'u/qef. I .5; MM I UNITED STATES PATENT ormcn ERNEST E. SWEET, or DETROIT, MICHIGAN, ASSIGNOR To CADILLAC MOTOR OAR COMPANY, or nn'rnorr, MICHIGAN, A CORPORATION or MICHIGAN.
" Specification of Letters Patent.
Patented July 14, 1908.
Application filed January 11, 1908. Serial N 0. 410,439.
To all whom it may concern:
citizen of the United States of America,
residing at Detroit, in the county of Wayne and State of Michi an, have invented certain new and useful mprovements in Worm- Gearing, of which the following is a specification, reference being had therein to the accompanying drawings. a
The inventlon relates to that type of steering ear in which rotation of the steering whee and stem is transmitted through the medium of a gear to a transversely-extending' rock shaft, arid from the latter to the mechanism for turning the wheels. In order that the. vehicle may be turned in a small space, it is necessary to provide a gear segment which may be adjusted through a relatively lar e angle but in the ordinary operation of t 1e apparatus, where the vehicle is merely guided in a substantially straight course, the angular movement imparted to the gear is veryslight. As a consequence, the wear in the gear teeth is chiefly limited to the central portion of the segment, and it is in this portion that it is most desirable to take up all lost motion, so that the vehicle angl will respond quickly to any movement of the steering wheel. Adjustment for taking up the lost motion is a simple matter, merely requiring the movement of the shaft on which the ear segment is mounted towards the axis 0 the cooperating gear member, but it is obvious that if such adjustment is made, to take up wear, limited to the central ortionof the gear segment, it will cause the inding of the'teeth on opposite sides of this central portion when the gear is moved through a. greater angle, thus rendering the gear practically ino erative; The resent invention is designer to overcome this difficulty by providing aconstruction in which adjustment may be made to compensate for wear in the central portion of the gear without interferingwith the operativeness of the apparatus when moved through a greater To this end the invention consists in a construction of worm gear which initially is provided with a slight clearance for the teeth of the outerportions of the segment when the axis of the gear shaft is properly adjusted to take u all lost motion in the central portion oft "e segment. ."With such a construction, when the central portion of ciple of 'onstruction thereof; and Figs. 3
and 4 are similar views illustrating modifications.
A is the rotary steering stem and B is the worm member mounted u on this stem and preferably within a suitab e housing 0.
,D is the worm gear, which is mounted upon the rock shaft E, and the latter is adjustably mounted in the casing preferably by being journaled in eccentric bearings F therein. In the cutting of the teeth on the gear segment D, instead of adjusting the center of rotation to coincide with the axis G of the rock shaft IE, it is adjusted to turn from a center H upon a sli htly lesser radius. This will result 1n provi ing a slight clearance for the teeth at o po'site ends of the segment D which gradua y diminishes as the center of the. segment is approached, and thus the re quired-adjustment for wear in the central portion of the segment is at any time permissibleQ With the constructiondescribed, adjustment may be made by any user of the machine without requiring the exercise of special mechanical skill. Furthermore, the wear in the gear tends to render it more rather than less perfect for it enlar es the segment in which the teeth are in ful mesh. The slight play between the teeth at the ends of the segment and the worm is immaterial for these partsare only in engagement whenthe steering wheels of the vehicle are turned at a decided angle, and at such times the re sistance of the wheels will keep the worm and gear in contact. On the other hand, where there is any play at the center of the gear there will be constant vibration and rattling, as there is no resisting force to hold the parts in contact.
The, adjustments which are provided in steering gears not constructed in accordance with my invention are only serviceable for factory 'adjustmentthat is, for originally setting the gears in proper place before they have been in use, but after wear such adjustments cannot be used for the reasons already set forth.
seeps-2 In Figs. 3 and. t modified constructions are illustrated, the former showing a pinion I. engaging e rack J, the teeth of which are slightly deflected from a straight line. I Fig. 4 s segmental rack, similar to that illustratedin Fig. 2, is employed, but is arranged to engage a straight gear or pinion K, instead oi the worm gear; Both of these constructions comedy the same principle the constructions illustrated in Figs. 1 and 2, Yl'zi, that the central portion of the rack has its teeth slightly in advance of the end portions thereof.
Vw hilc the present construction especially adapted for the steering mechanism of motor venicles, it is not, however, necessarily timited to such aeombina-tion, as it will be ohserved. that it can readily be adapted for various uses in other gear constructions, and also that the design and construction of the gearing may be varied without departing *rom my invention.
What i claim. as myinvention is:
1. in a gearing, cooperating interineshing members constructed to provide a slight clearance between the intermeshing portions thereof when moved from the normal position, while being in full engagement at the normal position.
2. In a gearing, cooperating intermeshing members constructed to provide a slight clearance when moved in either direction from the normal position while being in full engagement at the central or normal position. 3. in a gearing, cooperating gear memhers, the pitch line of the teeth of one of said members having a dillerent radius than the axis of rotation of said gear, for the purpose described. 40 4. A worm gearing, the pitch line of the teeth of the gear member thereof having a dill'erent radius than the axis of rotation of said gear, for the purpose described.
5. in a gearing, cooperating intermeshing memhers constructed to provide a slight clearance between the intermeshing portions thereof when moved from the normal position, while being in full engagement at the normal position, and means for ad'usting the relation of said cooperating members.
6. In agearing, cooperating gen-r members, the pitch line of the teeth of one of said members having a different radius than the axis of rotation of said gear, and means for adjusting the relation 01 the centers of said radii, for the purpose described.
In testimony whereof I afiix my signature in presence of two witnesses.
ERNEST E. SWEET Witnesses:
AMELIA WILLIAMs, NELLIE KmsELLA.