FINAL DRIVE GP 1333656 - Caterpillar

Illustration 1 g00794071
Hydraulic Schematic for Travel Motor Circuit (right travel motor) (1) Rotary group. (2) Gauge port (service). (3) Swashplate control piston. (4) Gauge port (stroking pressure). (5) Line relief valves. (6) External supply port. (7) Brake valve. (8) Check and relief valves. (9) Shuttle valve. (10) Brake pilot valve. (11) Port (pump oil). (12) External port (parking brake). (13) Internal port (parking brake). (14) Port (pump oil). (15) Gauge port (service). (16) Displacement change valve. (17) Case drain port. (18) Travel motor circuit.The travel motor can be divided into the following three groups:
The rotary group
The displacement change valve
The motor head Rotary Group
Illustration 2 g00791390
Rotary Group (3) Swashplate control piston. (19) Drive shaft. (20) Bearings. (21) Housing. (22) Pin. (23) Pistons. (24) Retainer. (25) Adjustment screw (output flow). (26) Barrel. (27) Spring. (28) Swashplate.The travel motors are piston type motors.The flow of the oil from the pump depends on the direction of travel. The oil from the pump flows into the travel motor through port (11) or port (14). Pump oil is forced out of the travel motor through port (11) or port (14) .The case drain oil returns to the hydraulic tank through a drain port on the head of the travel motor.The oil from the lower pump flows into the right travel motor through port (11) during forward travel. The oil from port (11) flows through an internal passage in the motor head. The oil then flows through a passage in swashplate (28) into barrel (26). The oil forces pistons (23) to move to the left.When piston (23) moves, barrel (26) rotates. Oil is discharged through a passage in swashplate (28) by pistons (23) as barrel (26) rotates. The oil flows through an internal passage in the motor head. The oil then flows through port (14). Pistons (23) are connected to output shaft (19) by retainer (24). Output shaft (19) rotates sending power to the final drives.Displacement Change Valve
Small Displacement Change Operation
When the travel speed control switch on the control panel is set at the HIGH SPEED position the travel speed solenoid valve that is located on the pilot manifold is de-energized. The pilot system oil flows through a port to displacement change valve (16) in the motor head.The pilot oil forces a spool in displacement change valve (16) to shift. Oil from the pump moves swashplate control piston (3). The angle of swashplate (28) decreases. As a result, the motor displacement is decreased and travel speed is increased.Large Displacement Change Operation
When the angle of swashplate (28) in the travel motor increases, the displacement of the travel motor increases. The angle of swashplate (28) in the travel motor will increase and the travel speed will decrease when the travel speed control switch is moved to the LOW SPEED position.When the travel speed control switch on the control panel is moved to the LOW SPEED position, the travel speed solenoid is energized. The pilot system oil is blocked. The spool in displacement change valve (16) is shifted by the