THEORY OF OPERATION - CONTINUED
POWERTRAIN - CONTINUED
Front and rear axle groups incorporate pinion and bevel gear sets, differential, final drives, and disc brakes. Front
and rear axle housings are slightly different, but internal components and operation are identical.
Power from transmission output shaft is transferred to front and rear axle groups by drive shafts. Power enters axle
groups through bevel pinion. Bevel pinion turns bevel gear. Bevel gear is fastened to differential case.
Power is transferred through differential by pinions and side gears to final drives. Final drive main components are
a carrier, planetary gears, ring gear, and sun gear. Each final drive has identical components. Final drives cause less
speed reduction and torque increase in drive train.
Sun gear is splined into differential side gear. Ring gear is pressed into axle housing. Three planetary gears are
mounted in carrier. Carrier has internal splines which mesh with splines of axle shaft.
As sun gear is driven by differential, planetary gears are forced to revolve around inside of ring gear. Movement of
planetary gears around ring gear causes carrier and axle shaft to rotate. This transfers power to rim and tire, which
bolt to flange on axle shaft.
Axle groups contain service brakes. Brake discs are splined to sun gear shaft. Brake discs rotate at a speed identical
to that of sun gear. When brakes are applied, a cavity behind brake piston is pressurized, causing brake piston to
clamp brake discs between piston and brake reaction plate.