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| Illustration 1 | g03266378 |
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Front Propel Motor (1) Propel motor (2) Drain line (3) Speed sensor (4) Brake line (5) Shift line | |
The machine is equipped with two propel motors, one for each drum. Front propel motor (1) is located on the right side of the front drum. The rear propel motor (not shown) is located on the left side of the rear drum. Each motor is an axial piston motor with two speeds. Each propel motor drives a drum through an integral planetary final drive.
A brake assembly is contained within each propel motor. When the interlock valve in the main hydraulic pump is energized, charge oil is directed from the pump into brake line (4). When this action happens, the parking brakes are released.
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 number one converts the frequency of the impulses to a machine speed.
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| Illustration 2 | g03266380 |
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Propel Motor Cylinder Block Cross Section (4) Brake line (5) Shift line (6) Valve plate (7) Swashplate (8) Power to drive wheel (9) Second stage planet gear (10) First and second stage ring gear (11) Brake piston (12) Brake spring (13) Disc package (14) Cylinder block (15) Piston (16) Slipper feet (17) Shift cylinder (18) Second stage planet carrier (19) Second stage planet gear (20) Second stage sun gear (21) First stage sun gear (22) First stage planet gear (23) First stage planet carrier | |
When the machine is moving, supply oil from the main hydraulic pump enters the motor. Supply oil is directed to the inlet port of valve plate (6). Supply oil is also directed to the flushing spool. The valve plate directs oil into the piston chamber in cylinder block (14). This pressure forces pistons (15) which are aligned with the inlet port to move out of the cylinder block.
As pistons (15) are forced out of cylinder block (14), slipper feet (16) follow the angle of swashplate (7). This action causes the cylinder block and pistons to rotate. Since the cylinder block is splined to the output shaft, the output shaft also rotates. The output shaft is splined to first stage sun gear (21) in the final drive.
As cylinder block (14) rotates, pistons (15) align with the outlet port in valve plate (6). The rotation of the cylinder block forces oil out of the piston chambers and into the low-pressure side of the hydrostatic loop. Low-pressure oil acts against the flushing relief valve. The low-pressure oil then returns to the inlet side of the hydraulic pump, which completes the hydrostatic circuit.
High-pressure oil acts against one side of the flushing spool (not shown), and low-pressure oil acts against the other. The force from the high-pressure oil causes the flushing spool to shift. The shift opens a passage for oil in the low-pressure circuit to act against the flushing relief valve (not shown). The flushing relief valve opens, which allows oil in the low-pressure circuit to flow into the motor case drain.
The angle of swashplate (7) determines the displacement of cylinder block (14). When the swashplate is at minimum angle, the motor operates at high speed and minimum torque. When the swashplate is at maximum angle, the motor operates at low speed and maximum torque. Shift cylinder (17) controls the angle of the swashplate.
When the propel system is operating in low mode, shift line (5) is connected to the tank. The shift spool (not shown) is shifted by springs into the low speed position. In this case, the shift spool blocks oil from the high-pressure circuit to shift cylinder (17). When this situation happens, the motor operates at maximum swashplate angle.
When the propel system is operating in high mode or roading mode, charge oil is directed through shift line (5). This charge oil acts against the shift spool and shifts the spool into the high speed position. In this case, the shift spool directs oil from the high-pressure circuit to shift cylinder (17). When this action happens, the shift cylinder pushes the swashplate to the minimum swashplate angle.
Disc package (13) is made of alternating discs splined to the shaft of the propel motor and to the brake housing. When the brake is applied, the disc package is compressed by the force of brake spring (12) acting through brake piston (11). In this case, the friction between the discs generates a holding torque that prevents rotation of the motor shaft.
When hydraulic oil is directed into brake line (4), hydraulic pressure acts against brake piston (11) to oppose brake spring (12). If sufficient pressure is applied, the brake piston moves and compresses the spring. This action removes the compression on disc package (13) and allows the motor shaft to rotate freely.
The final drive assembly contains two planetary gear assemblies. When the machine is moving, the output shaft of the propel motor turns first stage sun gear (21).
In the first stage planetary, sun gear (21) is driven and ring gear (10) is held. The interaction between the first stage sun gear and the ring gear causes first stage planet gears (22) to revolve around the sun gear. The movement of the first stage planet gears causes fist stage planet carrier (23) to rotate. The first stage planetary carrier is connected to second stage sun gear (20).
In the second stage planetary, the sun gear is driven and planet carrier (18) is held. Under these conditions, the planet gears cause ring gear (10) to rotate. The ring gear transfers power to drive wheel (8) through the hub of the motor.