SHAFT-PIVOT 0868552 - Caterpillar

Illustration 1 g03406944
Left Side of Drum
(1) Drum motor
(2) Case drain line
(3) Brake supply line
(4) Reverse port "B"
(5) Maximum displacement limiter
(6) Forward port "A"
(7) Shift port
(8) Flushing spool
(9) Flushing relief valve Drum motor (1) is located on the left side of the drum. This motor is a piston motor with two speeds. The drum motor drives the drum through a planetary gear reducer. The planetary gear reducer contains an integral parking brake.The parking brake is spring applied and hydraulically released. Brake supply line (3) on the gear reducer provides charge oil to release the parking brake.Depending on direction, the drum motor receives supply oil from the drum rotating group in the propel pump through forward port "A" (6) or reverse port "B" (4). The motor also returns low-pressure oil to the drum rotating group through these ports.Drum motor (1) contains a flushing valve. Flushing valve spool (8) directs oil from the low-pressure side of the drum propel loop to flushing relief valve (9). When the pressure in the low-pressure side of the propel loop is greater than the setting of the valve, the flushing relief valve opens. When the flushing relief valve is open, an orifice diverts oil from the low-pressure side of the drum propel loop into the drum motor case drain.Case drain line (2) for drum motor (1) directs oil from the drum motor case to the return manifold.Drum motor (1) is equipped with maximum displacement limiter (5) and a minimum displacement limiter (not visible). When the shift solenoid is not energized, the drum motor operates at maximum displacement for low speed operation. When the shift solenoid is energized, charge oil is directed into shift port (7). In this case, the motor operates at minimum displacement for high speed operation. Both displacement limiters can be adjusted to control the minimum and maximum motor speeds.
Illustration 2 g03406947
Motor Cross Section
(5) Maximum displacement limiter
(8) Flushing spool
(9) Flushing relief valve
(10) Output shaft
(11) Swashplate
(12) Piston
(13) Barrel assembly
(14) Servo piston
(15) Shuttle valve
(16) Slipper pad
(17) Slipper retainer
(18) Minimum displacement limiter
(19) Valve plate A pressure differential between the forward port and the reverse port of the motor causes the motor to rotate. When the supply pump is not generating flow, pressure in the forward circuit and pressure in the reverse circuit is equal to charge pressure. In this case, a pressure differential does not exist, and the motor will not turn.When the propel pump is generating flow, supply oil enters the motor. Supply oil is directed to the inlet port of valve plate (19). The valve plate directs oil into the piston chamber in barrel assembly (13). This pressure forces pistons (12) which are aligned with the inlet port to move out of the barrel assembly.As pistons (12) are forced out of barrel assembly (13), the barrel assembly and pistons rotate. Since the barrel assembly is connected to output shaft (10), the output shaft also rotates. As barrel assembly (13) rotates, pistons (12) align with the outlet port in valve plate (19). The rotation of the barrel