Torsional Shock Absorber; Backlash; Vacuum Pump Or Hydraulic Governor - Rotax 912 Series Operator's Manual

Torsional shock
absorber

Backlash

Vacuum pump or
hydraulic
governor
Page 7-8
November 01/2016
The design incorporates a torsional shock absorber. The shock
absorbing is based on progressive torsional cushioning due to
axial spring load acting on a dog hub.
On the gearbox version with overload clutch the design incorpo-
rates a friction damped free play at the dogs to warrant proper
engine idling. Due to this backlash at the dogs a distinct torsion-
al impact arises at start, stop and at sudden load changes, but
due to the built-in overload clutch it will remain harmless.
NOTE
This overload clutch will also prevent any undue load to the
crankshaft in case of ground contact of the propeller.
See Service Letter SL-912-015
Alternatively either a vacuum pump or a hydraulic governor for
constant speed propeller can be used. The drive is in each case
via the propeller reduction gear.
BRP-Rotax Effectivity: 912 Serie
Edition 4 / Rev. 0