Systems Description; Propeller Gearbox - Rotax MMH-912 Series Maintenance Manual

2) Systems description

2.1)

Propeller gearbox

See Fig. 72 -1
Transmission gear ratio crankshaft: propeller shaft 2.43 : 1
The propeller shaft is driven by the crankshaft via a straight toothed spur gear
(1).
The propeller gearbox incorporates a torsional shock absorbing device. This
consists of a torsional shock absorber with dogs (2) and axial springloading by
means of disc springs (3).
The design also includes a friction damped free rotation at the dogs to ensure
smooth engine idling. Due to this free rotation, a distinct torsional impact arises
at engine start and stop and in the event of sudden load changes, but due to the
integrated overload clutch it will remain harmless.
◆ NOTE:
◆ NOTE:
2.1.1)
912 A, F, UL
1)
912 S, ULS, ULSFR
2)
914 F, UL
3)
4) 912 A, F, UL - optional
Effectivity 912/914 Series
Edition 1 / Rev. 0
BRP-Rotax
Maintenance Manual
This overload clutch (4) will also prevent any undue load on the
crankshaft in the event of the propeller having ground contact.
The overload clutch is fitted in serial production on both certified
aircraft and uncertified aircraft engines of configuration 3.
Gearbox version
See Fig. 72 -1
There are 3 gearbox configurations for the 912/914 Series. See 71-00-00
sec. 2.2
; 2.27 : 1
2), 3), 4) 1)
72-00-00
page 5
May 01/2007