VALVE GP-PILOT 2075207 - Caterpillar

Drum Motor
Illustration 1 g06132374
Left Side of Machine
(1) Drum motor
(2) Port"B"
(3) Maximum displacement limiter
(4) Port"A"
(5) Port"X"
(6) Port"L"
(7) Flushing relief valve
(8) Flushing valve spoolDrum motor (1) is on the left side of the drum. The drum motor drives the drum through a planetary gear reducer. The planetary gear reducer contains an integral parking brake.Drum motor (1) is an axial-piston motor with variable displacement. During forward operation, the motor receives supply oil from the drum rotating group at forward port"A" (4). The motor returns low-pressure oil through reverse port"B" (2). During reverse operation, pump supply oil is delivered to port"B" of the motor. Return oil flows out of port"A" of the motor.The case drain port for drum motor (1) is at port"L" (6). Case drain oil from this port is sent directly to the return manifold.Drum motor (1) contains a flushing valve. Flushing valve spool (8) directs oil from the low-pressure side of the drum propulsion loop to flushing relief valve (7). When the pressure in the low-pressure side of the propulsion loop is greater than the setting of the valve, the flushing relief valve opens. When the flushing relief valve opens, low-pressure oil from the drum propulsion loop flows through an orifice and into the drum motor case drain.Drum motor (1) is equipped with maximum displacement limiter (3) and a minimum displacement limiter (not visible). When the shift solenoid is not energized, the drum motor operates at maximum displacement. In this case, the motor operates at low speed with high torque. When the shift solenoid is energized, the motor operates at minimum displacement. In this case, the motor operates at high speed with low torque. Displacement for the motor is adjustable.The brake inlet line (not shown) on the drum final drive provides charge oil to release the parking brake.
Illustration 2 g06132372
Drum Motor Cross-section
(3) Maximum displacement limiter
(7) Flushing relief valve
(8) Flushing valve spool
(9) Output shaft
(10) Swashplate
(11) Piston
(12) Barrel assembly
(13) Servo piston
(14) Shuttle valve
(15) Slipper pad
(16) Slipper retainer
(17) Minimum displacement limiter
(18) Valve plateThe speed of the drum motor shifts when angle of swashplate (10) is changed. The motor can be operated against either minimum displacement limiter (17) or maximum displacement limiter (3). The minimum displacement limiter or the maximum displacement limiter can be adjusted to control minimum and maximum motor speeds.A pressure differential between the forward port and the reverse port of the motor causes the motor to rotate. When the propulsion pump is not generating flow, pressure in the forward circuit and reverse circuit is equal to charge pressure. In this case, a pressure differential does not exist, and the motor will not turn.When the propulsion pump is generating flow, supply oil enters the motor. Supply oil is directed to the inlet port of valve plate (18). The valve plate directs oil into the piston chamber in barrel assembly (12). This pressure forces pistons (11) which are aligned with the inlet port to move out of the barrel assembly.As pistons (11) are forced out of barrel assembly (12), the barrel assembly and pistons