0134

Item 0134

DESIGN: Power Train - Reduction - Secondary - Teeth Layout 25/19/63

Drawing:

Layout drawing to locate teeth of sun, ring and 4 planetary gears re correct meshing.

Conversation with design engineer at The Gear Works re planetary gears:

Tooth count:

The sum of the teeth in the sun gear plus the ring gear must be divisible by the number of planet gears. In the above 25 + 63 = 88 and 88 is divisible by 4.

All of the following is on 0772 also
Gear designer:

He recommended the following person as being very knowledgeable of planetary gearing and also that Ray has done it for aircraft applications. Ray Drago at Drive Systems Technologies; 1-(610)-358-0785; gear-doc@worldnet.att.net.

Span measurement on ring gear:

Re the unusual tooth count on the Bell 206. He said the distance between teeth on the ring gear may differ from standard so as to get proper meshing between internal and external teeth.

4 or more planetary gears:

If more than 3 planetary gears are used then;

the tooth thickness of all teeth in all planetary gears must be very accurate. If a large run is done then the tooth thickness should be measured later and the gears grouped by similarity.
The location of the axis of all planetary gears in the planetary holder must be extremely accurate. With 3 planets the sun can float.

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Last Revised: April 29, 2000