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From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Description of Gleason Hypoid Gears, outlining their function and advantages.

Identifier  ExFiles\Box 136\5\  scan0131
Date  26th January 1926
  
Wa{Mr Wallis}: For you to take to Eng. X2060
Am sending a copy to Mr Cyril

GLEASON HYPOID GEARS

January 26 1926

DESCRIPTION

Hypoid (or hyperboloid) gears are most easily understood by comparison with bevel gears which they will, in many cases, replace. They get their name from the fact that the pitch surfaces are hyperboloids of revolution, instead of being conical surfaces, as in the case of bevel gears. In general, they look like bevel gears, the most striking point of difference being that the axes of gear and pinion do not intersect, but are offset from each other by an amount which varies according to the design. In the case of rear axle gears for automobiles a range of one and one half to three and a half inches will cover most cases.

Only hypoid gears with teeth curved across the face to give continuous tooth to tooth contact are being considered at present; that is, they resemble spiral bevel gears rather than straight tooth bevels.

If a pair of hypoid gears is thought of as replacing a pair of spiral bevel gears, the number of teeth in gear and pinion will, in general, remain the same. The gear diameter will be the same or slightly less and the pinion diameter will be greater.

The tooth action of hypoid gears combines the rolling action of bevel gears with a percentage of endwise sliding.

The drive is as easily reversible as in the case of the usual bevel gears.

A recent development by the Gleason Works makes the production of hypoid gears as practical an operation as the cutting of spiral bevel gears, and renders them available for automobile rear axle and other uses.

ADVANTAGES:

The chief advantages of the hypoid gears are noiseless operation, increased load carrying capacity for the same gear diameter, or reduced gear diameter for equal transmitted loads, the possibility of high reduction, long life, high efficiency, lower floor boards or increased road clearance.

Hypoid gears have been demonstrated in rear axles and in testing machines to be extremely quiet. The tooth action is a combination of the features that make a pair of spiral bevels quiet with a slight endwise sliding action. That is to say, they have the over-lapping feature due to the spiral

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Gleason Works - Rochester, New York
  
  


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