Posted by BillS on March 01, 2009 at 12:28:24:
An associate has a Liebherr 252 hobber and his differential formula is:
9.375 x Sin(Helix Angle)
Mn Zo PI
This formula seems to force very small decimal ratios even for reasonable modules and angles. For example, a 20T gear 10NDP and 15 Deg Helix result in a 0.0152 decimal ratio, not to be found in a 4-gear set from 20-100T change gear inventory. Either the 9.375 is too small, or there is something I'm missing.
Mn is Module and Zo is number of teeth, right?
Is there something else that influences the differential formula - a tangential hob shift or feed, or ??