Rolf Pfeiffer wrote:

 I am making reference to these combinations.

 " Paul,
 > Matey - you've got me stumped again !!
 > 71 teeth /33 = 2.15
 > 72 teeth/33 = 2.18
 > 78 teeth/36 = 2.17
 > 78 teeth/42 = 1.85 ( +1 =2.85)
 > How many planetary/ratios are there available !!?"

 Please note that the difference in teeth number between the ring gear
 and the sun gear must be an even number. The difference is divided by
 two to obtain the number of teeth in the planetary idler gears. An
 uneven difference would result in a planetary gear with a half tooth.
 e.g. (72 - 33) / 2 = 39/2 = 19.5 teeth.
 (The local gear manufacturer refuses to make these :))  Rolf Pfeiffer

Ken Welter wrote:

  Don't forget about the 3.17 to 1
  I ran a Ross 3.17 for about 400 hrs and loved that ratio.

  Ken Welter

That must be the 2.17 set.
If you remove power from the planet carrier  and hold the ring gear 
on the 2.17 you get about 4.4 P.D./2 P.D. + 1 = 3.2:1 about.

Paul Lamar
 
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