Engine Gear Reduction System - Textron Cessna Grand Caravan Ex 208B Pilot's Operating Handbook And Faa Approved Airplane Flight Manual

CESSNA SECTION 7
MODEL 208B 867 SHP AIRPLANE AND SYSTEMS DESCRIPTION
GARMIN G1000

ENGINE GEAR REDUCTION SYSTEM

The reduction gear and propeller shaft, located in the front of the
engine, are housed in two magnesium alloy castings which are bolted
together at the exhaust outlet. The gearbox contains a two-stage
planetary gear train, three accessory drives, and propeller shaft. The
first-stage reduction gear is contained in the rear case, while the
second-stage reduction gear, accessory drives, and propeller shaft are
contained in the front case. Torque from the power turbine is
transmitted to the first-stage reduction gear, from there to the second
stage reduction gear, and then to the propeller shaft. The reduction
ratio is from a maximum power turbine speed of 33,000 RPM down to a
propeller speed of 1900 RPM.
The accessories, located on the front case of the reduction gearbox,
are driven by a bevel gear mounted at the rear of the propeller shaft
thrust bearing assembly. Drive shafts from the bevel drive gear transmit
rotational power to the three pads which are located at the 12, 3 and 9
o'clock positions. Propeller thrust loads are absorbed by a flanged ball
bearing assembly located on the front face of the reduction gearbox
center bore. The bevel drive gear adjusting spacer, thrust bearing, and
seal runner are stacked and secured to the propeller shaft by a key
washer and spanner nut. A thrust bearing cover assembly is secured
by bolts at the front flange of the reduction gearbox front case.
208BPHCUS-00 7-73
U.S.