HIGH REDUCTION HYPOIDS

A RECENT development has been in the direction of very high ratios in hypoid gears. A slight modification from the usual design of hypoids makes it possible to go as low as one tooth in the pinion. Ratios as high as 60 to 1 have been made, and much higher ratios are possible. (Illustration No. 32).

In the photograph are shown two pairs of such gears, one a combination of 2 to 38 teeth, with a gear of 4 3/8" diameter and the pinion of tapering form; and the other a 2 to 60 tooth combination, with a gear of 9" diameter and pinion of parallel form. These gears are made on the Gleason Hypoid Generators previously shown, using face mill cutter or cup grinding wheel on both members. The number of teeth in contact is four on one pair and nine on the other. This feature of large number of teeth in contact, coupled with the fact that both numbers can be ground, provides high load carrying capacity and extreme accuracy of motion. Actual tests for 500 hours on the 2-38 combination with both members of hardened steel and ground showed 82% efficiency. This was with the pinion lubrized and with ordinary machine oil as lubricant. Tooth load was 450 pounds per inch of face. This development opens up a wide field of applications (indexing mechanisms, speed reducers, steering gears, household appliances) to mention a few.