| 摘要 |
1,238,008. Toothed gearing. H.S.G. S.p.A. 14 Feb., 1969 [21 Feb., 1968], No. 8038/69. Heading F2Q. For each of a meshing pair of helical gears 1,2 having parallel axes, on the base circle db 1 or db 2 the tooth thickness S bt1 or S bt2 is greater than the tooth pitch P bt1 or P bt2 , on the reference cylinder d 1 or d 2 the tooth thickness equals the tooth pitch, and the entire tooth flanks are active and involute. The reference cylinder is that on which the normal pressure angle has the specified standard value (B.S. 2519 : 1954). The ratio of the cosine of the reference helix angle to the reference normal pitch is the same for both gears. The gears are generated by basic racks 1 0 , 2 0 having symmetrical plane flank teeth arranged with their datum planes X 1 , X 2 tangential to the reference cylinders d 1 , d 2 of the gears, the datum planes being the planes in which the rack tooth thickness is zero. It is stated that the gear ratio of a gear pair 1, 2 is independent of the average diameters of the teeth, that a one-tooth pinion is possible, and that an irreversible drive is obtained. |
