File:Worm gearing (1916) (14801800313).jpg

Identifier: wormgearing00thom (find matches)
Title: Worm gearing
Year: 1916 (1910s)
Authors: Thomas, Hugh Kerr
Subjects: Gearing, Worm
Publisher: New York : McGraw-Hill Book Co.
Contributing Library: The Library of Congress
Digitizing Sponsor: The Library of Congress

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rongly ribbed brackets for carrying the bearings of the wormwheel, the whole forming the lid of the axle case proper. Bythis arrangement the assembling of the gears and their exactadjustment can be carried out on the bench with the worm andwheel in full view, giving every facility to the erector for correctlocation in their relative positions; such a method also enables anaccurate machining operation to be carried out upon the mainbearings of the gear, and, when examination is necessary, itcan be made without disturbing any adjustments, the entiresystem of worm wheel, and differential with all their bearingsbeing lifted out in one piece for the purpose. Much latitude is permissible to the designer, who has a widefield of arrangements to select from; it must always beremembered that the stresses in the parts supporting the bear-ings are high, but with the use of the diagram, Fig. 19, theymay be determined at a glance, and a selection of suitableball bearings can bie made. 78 WORM GEARS
Text Appearing After Image:
COCO 6 GENERAL POINTS OF DESIGN OF MOUNTING 79 It may be observed that in the case of a straight worm, thatis, one having a cyHndrical pitch line, a double thrust bearingshould be provided at one end (whichever is most convenient)the other end can then be left free to expand or contract withthe difference of temperature which occurs when the worm isrunning. In the case of the hour-glass pattern worm, it isdifficult to say what happens when it has to expand, presumablythe casing expands too, and in that case a single thrust bearingat either end is the better arrangement. Some designers provide a very heavy thrust bearing to takethe forward drive and a relatively light one for the reverse—•it is hard to see any justification for such an arrangement, sincethe reverse gear is almost invariably lower than the first speedforward, and the torque at the worm pitch line, and all theresultant pressures are in consequence heavier. Provision must be made for oil to reach the thrust bearingat

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