ENGINE AR-COMPLETE 1498988 - Caterpillar

Illustration 1 g06172639
Front Propel Motor
(1) Propel motor
(2) Shift line
(3) Speed sensor
(4) Brake line
(5) Brake assemblyThe machine is equipped with two propel motors, one for each drum. Front propel motor (1) is on the right side of the front drum. The rear propel motor (not shown) is on the left side of the rear drum. Each motor is a radial-piston motor with two speeds.On front propel motor (1), the forward supply port is labeled "A". The reverse supply port is labeled "B".Note: On the rear propel motor, port "B" is the forward supply port, and port "A" is the reverse supply port.Brake assembly (5) is mounted on each propel motor. When the interlock valve in the propel pump is energized, charge oil is directed from the pump into brake line (4). When this action happens, the parking brakes are released.Shift line (2) receives supply oil from the shift valve. When the shift valve is energized, charge oil is directed to the shift line and the motor shifts to high-speed mode.Note: When the propel mode is set to high or roading, the front propel motor operates in the high-speed mode and the rear propel motor operates in the low speed mode. This combination of operating modes provides better gradability and braking performance than by operating both drum motors in the high-speed mode.Each motor is equipped with speed sensor (3). A gear on the output shaft of the motor rotates past the tip of the speed sensor. Each time a tooth passes the sensor, an electrical impulse is generated. The machine ECM converts the frequency of the impulses to a machine speed.
Illustration 2 g06172642
Cross Section, Propel Motor Cylinder Block
(A) Low speed operation (full displacement)
(B) High-speed operation (half displacement)
(6) Output shaft
(7) Cam ring
(8) Cylinder block
(9) Cam follower
(10) Piston
(11) Distribution channel 3
(12) Distribution channel 2
(13) Distribution channel 1Cam ring (7) and control valve (not shown) in the radial-piston motor are stationary. Cylinder block (8) and pistons (10) rotate with output shaft (6). During motor operation, each piston in the motor goes through a four-phase cycle. The phases in the cycle correspond with the cam follower position in relation to the lobes of the cam ring.When cam follower (9) is at the highest point on the cam lobe (relative to the center of the motor), piston (10) is in the top-neutral phase. At this point, the piston chamber is not connected to either an inlet or an outlet port. When the cam follower is on the downhill face of the cam lobe, the