TM 5-3895-373-34
1.17
HYDRAULIC PROPULSION MOTOR.
The paving machine uses two hydraulic propulsion
motors. A separate motor is used for the right and left
side. The left motor is powered by the left hydraulic
propulsion pump and the right motor is powered by the
right
hydraulic
propulsion
pump.
The
following
description applies to either motor.
The hydraulic propulsion motor is a bent axis, piston
type, high torque, variable speed, bi-directional motor. It
has a maximum displacement of 3.05 cubic inches
(49,98 ml) and a minimum displacement of 1.13 cubic
inches (18,52 ml) per revolution. Operating pressure is
5000 psi (34 475 kPa). The charge pump in the left
propulsion pump provides flow and pressure, 350 psi
(2413 kPa), to the high speed shift valve. The high
speed shift valve controls the paving speed and travel
speed of the propulsion motors.
Oil flow through the high speed shift valve positions the
motor control piston. The control piston is linked by a
shaft to the cylinder block and sets the angle at which the
cylinder block turns. The greater the angle of the
cylinder block, the slower the motor turns; the lesser the
angle, the greater the speed output.
The cylinder block contains seven pistons. Each piston
applies force, through a connecting rod, to the drive shaft
output flange causing the output flange to rotate. High
pressure oil forces the pistons out, which causes a
downward rotation on the output flange. Rotation of the
output flange produces a rotation of the output drive
shaft. Meanwhile, pistons on the opposite side of the
flange are retracting, forcing the oil out at low pressure,
back to the reservoir.
The propulsion motors are cooled by controlled fluid
leakage. A three-way, pressure driven, flushing valve
allows heated hydraulic oil to exit the system and return
to the hydraulic reservoir.
1.18
SPEED REDUCTION GEARBOX.
The speed reduction gearbox links the hydraulic
propulsion motors to the track hubs and drive sprocket
gears. There is one reduction gearbox for each track.
The reduction gearbox is a triple-stage unit with a
reduction ratio of 65:6:1 and a continuous operating
torque of 4700 lb-ft (6372 N•m).
1-9
