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| Illustration 1 | g01066995 |
The front drum motor is located on the left side of the front drum. The rear drum motor (1) is located on the right side of the rear drum on the double drum vibratory compactors. The drum motors contain integral parking brakes. The front drum motor and the rear drum motor are identical.
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| Illustration 2 | g01066997 |
On the CB-225E, the right rear propulsion motor (2) drives the right pair of wheels. The left rear propulsion motor (3) drives the left pair of wheels. The right propulsion motor and the left propulsion motor are identical to each other, and the propel motors are similar to the drum propel motors. These motors contain integral parking brakes.
Drum Propel Motor
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| Illustration 3 | g01067216 |
(1) Valve (2) Brake Piston (3) Brake Spring (4) Cylinder Block (5) Output Shaft (6) Piston (7) Cam Follower (8) Cam Ring | |
The drum propel motors are radial piston motors with integral parking brakes. The parking brakes in the wheel propel motors are spring applied and hydraulically released. When the parking brake switch is off, charge oil is directed into the piston chamber of each brake. Charge pressure acts against the brake piston. The charge pressure overcomes the spring force, moving the brake piston, and disengaging the brake.
When the parking brake switch is OFF and the propulsion lever is in FORWARD, pump supply oil is sent into the forward port of the motor, and the reverse port of the motor sends the return oil back to the pump. Internal passages of the motor direct the supply oil to the valve which distributes supply oil to some of the piston chambers. The valve blocks chambers and the remainder of the chambers to the reverse port are open.
The pressure oil in the piston chambers causes the pistons to move out of the cylinder block. As the pressurized pistons move out of the block, the cam followers cause all of the pistons to follow the contour of the cam ring, and the cylinder barrel rotates with the pistons. This rotation is transferred to the output shaft, which is connected to the drum.
Wheel Propel Motor
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| Illustration 4 | g01067019 |
The wheel motors on the CB-225E are radial piston motors with integral parking brakes. The left wheel motor and the right wheel motors are identical. The operation of the wheel motors is similar to the operation of the drum motors with the exception of the parking brakes.
The parking brakes in the wheel propel motors are spring applied and hydraulically released. When the parking brake switch is OFF, charge oil is directed into the piston chamber of each brake. Charge pressure acts against the brake piston. The charge pressure overcomes the spring force. The brake piston moves. This releases the force on the disks and the plates.
Cylinder Block of The Propel Motor
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| Illustration 5 | g01067027 |
The cam ring and the valve in a radial piston motor are stationary, while the cylinder block and the piston rotates. Each piston in the motor goes through four cycles during the motor operation. The phases in the cycle correspond to the position of the cam follower in relation to the lobes of the cam ring.
When the cam follower is at the highest point on the cam lobe relative to the center of the motor, the piston is in the top neutral phase. At this point, the piston chamber is not connected to an inlet or an outlet port. When the cam follower is on the downhill face of the cam lobe, the piston is in the full power phase. During this phase, the piston chamber is connected to an inlet port, and the pump supply oil fills the chamber. The supply oil forces the piston out of the barrel and the cam follower to move down the cam lobe.
The piston chamber remains connected to the inlet port until the cam follower reaches the lowest point in the valley of the cam ring. At this point, the piston is in the bottom neutral phase, and the piston chamber is not connected to an inlet or an outlet port. When the cam follower is on the uphill face of the cam, the piston chamber is open to the return line, and the piston is in the discharge phase. During the discharge phase, the piston moves in toward the center of the motor, and the oil in the piston chamber flows into the outlet port.