Spiral And Worm Gearing

SPIRAL AND WORM GEARING SPIRAL AND WORM GEARING A TREATISE ON THE PRINCIPLES, DIMENSIONS, CALCULATION AND .DESIGN OF SPIRAL AND WORM GEARING, TOGETHER WITH CHAPTERS ON THE METHODS OF CUTTING THE TEETH IN THESE TYPES OF GEARS COMPILED AND EDITED BY ERIK OBERG, A.S.M.E. ASSOCIATE EDITOR or EDITOR OF AUTHOR OF " MACHINERY MACHINERY'S HANDBOOK HANDBOOK OF SMALL TOOLS," " SHOP ARITHMETIC FOR THE MACHINIST," " SOLUTION OF TRIANGLES," " STRENGTH OF MATERIALS," "ELEMENTARY ALGEBRA," ETC. FIRST EDITION FIFTH PRINTING NEW YORK THE INDUSTRIAL LONDON: PRESS THE MACHINERY PUBLISHING IQ20 CO., LTD. COPYRIGHT, 1914 BY THE INDUSTRIAL PRESS NEW YORK PREFACE THE manner For pinion, To results are so nearly alike that the previous cal- may find the 7 ^= r 28, approximately. find the lead of the tooth helix, use Lead Lead for gear for pinion = = 3.1416 X X 30 6.928 3.1416 find the addendum, use Rule 7 X X Rule cot 60 cot 30 To Addendum = ^ = 0.333 inchTo find the whole depth of tooth space, 2>I 57 = 0.719 inch. Whole depth = 6: = = 54.38 inches. 37.70 inches. : use Rule 8: o To Rule find the normal tooth thickness at the pitch line, use 9: Tooth thickness = '' =0.523 inch. o To find the outside diameter, use For gear, 30 For pinion, 6.928 Rule 10: + 0.666 = 30.666 inches. + 0.666 = 7.594 inches. This concludes the calculations for this example. If it is required that the pitch diameters of both gears be more nearly alike, the tooth angle of the gear must be decreased, and that of the pinion increased. Suppose we have a case in which the requirements are the same as in Example i, but it is required that both gears shall have the same tooth angle of 45 degrees. Under these conditions the addendum, whole depth of tooth and normal thickness at the pitch line would be the same, but the other dimensions would be altered as below: Pitch diameter of gear = ** 3 Pitch diameter of pinion - -- = X cos 45 3 X 3 = 21.216 inches. 5 = cos 45 8.487 inches. SPIRAL GEARING 8 o Center ,. , distance Number = 21.216+8.487L = of teeth for For gear, = ^ - (cos 45 For pinion. select cutter: 127, approximately, ; -, (cos 45 Lead which to -^-z 3 =51, approximately. ) = of helix for gear 3.1416 = Lead = of helix for pinion Outside diameter of gear Outside diameter of pinion Examples of the of Calculations = = X 21.216 X cot 45 66.65 inches. X 8.487 X cot 45 26.66 inches. 3.1416 = made , . 14.851 inches. <