Type "A" Travel Motor
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| Illustration 1 | g00861520 |
Travel Motor (1) Drive shaft (2) Stopper (3) Piston (4) Swashplate (5) Ball guide (6) Spacer (7) Spring (8) Barrel (9) Piston guide (10) Check valve (11) Check valve (12) Passage (13) Brake pilot valve (14) Port (15) Valve plate (16) Head (17) Stopper (18) Piston (19) Slipper (20) Retainer (21) Piston (22) Friction plate (23) Separator plate (24) Passage (25) Passage (26) Spring (27) Brake piston (28) Port (29) Drain port (30) Port (31) Port (32) Spool (33) Spring (34) Displacement change valve | |
The travel motor can be divided into the following three groups:
- The rotary group consists of drive shaft (1), ball guide (5), spacer (6), spring (7), barrel (8), slipper (19), retainer (20), and pistons (21) .
- The parking brake group consists of friction plates (22), separator plates (23), piston guide (9), spring (26), brake piston (27), and brake pilot valve (13) .
- The displacement change valve consists of displacement change valve (34), check valves (10) and (11), and pistons (3) and (18) .
Operation
The path of the oil depends on the travel direction. Pump oil flows into the travel motor through port (30) or through port (31). Then, the oil is forced outward through port (31) or through port (30). The case drain oil that has leaked from the sliding surfaces and from the clearances returns to the hydraulic tank through drain port (29) in head (16) .
Supply oil from the lower pump flows in the left travel motor through port (31) during forward travel. The oil from port (31) flows through passage (12) in head (16) to passage (25) of valve plate (15). The oil now flows through passage (24) of barrel (8). This forces piston (21) to the left.
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| Illustration 2 | g00861534 |
Motor Passages (side view from head (16) ) (24) Passage (barrel) (25) Passage (valve plate) (35) Passage (valve plate) | |
Slipper (19), which is coupled to the piston, slides on the surface of swashplate (4) from the top center to the bottom center. Slipper (19) also rotates with barrel (8). The oil that is forced outward by the pistons on the outlet side flows through passages (24) and (35) of valve plate (15) and out through port (30). The barrel turns counterclockwise.
Drive shaft (1) is splined to the barrel. The drive shaft and barrel rotate counterclockwise for forward travel.
During reverse travel, port (31) functions as an oil return port and port (30) functions as a supply port. The left travel motor rotates clockwise.
As the right travel motor is supplied upper pump oil through port (30), the right travel motor turns clockwise for forward travel. Pump oil through port (31) turns the motor counterclockwise for reverse travel.
Parking Brake
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| Illustration 3 | g00861542 |
Parking Brake (partial view) (1) Brake pilot valve (2) Port (3) Drive shaft (4) Head (5) Passage (6) Spring (7) Body (8) Barrel (9) Friction plate (10) Separator plate (11) Piston guide (12) Piston chamber (13) Brake piston (14) Passage | |
As pump oil is supplied to the travel motor, the parking brake is released and the motor starts rotation. When pump oil is not being supplied to the motor, the motor stops rotation and the parking brake mechanically engages.
In the parking brake section of the travel motor, friction plates (9) are splined to barrel (8). Separator plates (10) are splined to body (7).
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| Illustration 4 | g00861559 |
Brake Pilot Valve (2) Port (5) Passage (15) Spring (16) Valve (17) Retainer (18) Orifice | |
When no pump oil is supplied to the travel motor, brake piston (13) is pushed to the left by the force of spring (6). The oil in piston chamber (12) now flows to passage (14). The oil now flows through passage (5), and through orifice (18) of valve (16) in brake pilot valve (1) to the motor case drain. Friction plates (9) and separator plates (10) are held together against body (7) by the force of spring (6). Spring (6) is working against brake piston (13). The rotation of barrel (8) stops and drive shaft (3) engages the parking brake.
Orifice (18) restricts return oil flow from piston chamber (12). The restriction of the return oil flow delays the application of the parking brake. The parking is delayed in order to provide time for the machine to stop. This helps prevent earlier wear and/or damage.
Prior to the operation of the travel motor, a portion of pressure oil will flow to port (2) and open valve (16). The oil then flows through passages (5) and (14) to piston chamber (12). Brake piston (13) moves to the right against the force of spring (6). The pressure oil that is holding friction plates (9) and (10) together is released. This allows barrel (8) and drive shaft (3) to turn.
Displacement Change Valve
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| Illustration 5 | g00861567 |
Speed Change Valve (1) Swashplate (2) Piston (3) Piston chamber (4) Passage (5) Piston (6) Piston chamber (7) Passage (8) Displacement change valve (9) Port (10) Passage (11) Port (12) Check valve (13) Check valve (14) Port (15) Drive shaft | |
Large Displacement Change Operation
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| Illustration 6 | g00861589 |
Displacement Change Operation (large displacement) (1) Swashplate (2) Piston (3) Piston chamber (4) Passage (5) Piston (6) Piston chamber (7) Passage (8) Displacement change valve (9) Port (10) Passage (11) Port (12) Check valve (13) Check valve (14) Port (16) Passage (17) Passage (18) Passage (19) Adapter (20) Spring (21) Spool (22) Passage | |
When the travel speed control switch is placed in the LOW SPEED MODE position, the travel speed solenoid valve is not energized. Pilot oil is not supplied to port (9) of displacement change valve (8). The force of spring (20) moves spool (21) to the left until the spool comes in contact with adapter (19) .
The pump oil from port (14) flows through check valve (13), passage (10), passage (22), and passage (7). The oil then flows to piston chamber (6). Swashplate (1) is turned clockwise at a increased angle.
The oil in piston chamber (3) drains into the hydraulic tank through passages (4), (16), (17), and (18) .
The motor holds swashplate (1) in the maximum angle position.
Small Displacement Change Operation
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| Illustration 7 | g00861597 |
Displacement Change Operation (small displacement) (1) Swashplate (2) Piston (3) Piston chamber (4) Passage (5) Piston (6) Piston chamber (7) Passage (8) Displacement change valve (9) Port (10) Passage (11) Port (12) Check valve (13) Check valve (14) Port (18) Passage (20) Spring (21) Spool (22) Passage (23) Passage (24) Passage | |
When the travel speed control switch is placed in the HIGH SPEED MODE position, the travel speed solenoid valve is energized. If the pump delivery pressure is below a certain level, due to a smaller machine load, pilot oil flows to port (9) of displacement change valve (8). Pilot oil moves spool (21) to the right against the force of spring (20). Passage (22) closes and passage (24) opens.
The pump oil flows through passages (10), (24), and (4) into piston chamber (3). Piston (2) moves up. Swashplate (1) rotates decreasing the angle.
The oil in piston chamber (6) drains into the hydraulic tank through passages (7), (23), and (18) .
The motor holds swashplate (1) at the minimum angle position.
Type "B" Travel Motor
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| Illustration 8 | g00479800 |
Travel Motor (1) Drive shaft (2) Stopper (3) Piston (4) Swashplate (5) Slipper (6) Retainer (7) Barrel (8) Piston guide (9) Check valve (10) Check valve (11) Passage (12) Pilot valve (brake) (13) Port (14) Valve plate (15) Head (16) Stopper (17) Piston (18) Guide (19) Spacer (20) Spring (21) Piston (22) Friction plate (23) Separator plate (24) Passage (25) Passage (26) Spring (27) Brake piston (28) Port (29) Drain port (30) Port (31) Port (32) Spool (33) Spring (34) Displacement change valve | |
The travel motor can be divided into the following three groups:
- The rotary group consists of the following components: drive shaft (1), spring (20), spacer (19), piston (21), barrel (7), guide (18), slippers (5) and retainer (6) .
- The parking brake consists of the following components: friction plates (22), separator plates (23), spring (26), brake piston (27), piston guide (8) and brake pilot valve (12) .
- The displacement change valve consists of the following components: displacement change valve (34), check valve (9), check valve (10), piston (3) and piston (17) .
Operation
The flow of the pump oil depends on the direction of travel. Pump oil flows into the travel motor through port (30) or port (31). Pump oil is forced out of the travel motor through port (31) or (30). The case drain oil that has leaked returns to the tank through the drain port of head (15) .
Supply oil from the lower pump flows into the left travel motor through port (31) during forward travel. The oil from port (31) flows through passage (11) in head (15). The oil then flows through passage (25) of valve plate (14). The oil then flows through passage (24) of barrel (7). The oil forces piston (21) to move to the left.
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| Illustration 9 | g00479893 |
Motor Passage (side view from head) (A) Top center (B) Outlet side (low pressure) (C) Bottom center (D) Inlet side (high pressure) (24) Passage (barrel) (25) Passage (valve plate) (35) Passage (valve plate) | |
Slipper (5) is coupled to the piston. Slipper (5) and the piston slide on the surface of swashplate (4) from the top center to the bottom center. Slipper (5) and the piston rotate with barrel (7). The pistons force oil out of the outlet side of the motor passage. The oil flows through passage (24) and passage (35) of valve plate (14). The oil then flows through port (30). The barrel turns counterclockwise.
Drive shaft (1) is splined to the barrel. The shaft and barrel rotate counterclockwise for forward travel.
In reverse travel, port (30) functions as an oil return port. Port (31) functions as a supply port. The left travel motor rotates clockwise.
Pump oil through port (30) turns the right travel motor clockwise for forward travel. Pump oil through port (31) turns the right travel motor counterclockwise for reverse travel.
Parking Brake
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| Illustration 10 | g00479801 |
Parking Brake (partial view) (1) Drive shaft (7) Barrel (8) Piston guide (12) Pilot valve (brake) (13) Port (15) Head (22) Friction plate (23) Separator plate (26) Spring (27) Brake piston (36) Passage (37) Housing (38) Piston chamber (39) Passage | |
Pump oil is supplied to the travel motor. The parking brake is released and the motor starts rotating. When no pump oil is supplied to the motor, the motor stops and the parking brake engages.
In the parking brake section of the travel motor, separator plate (23) is splined to housing (37). Friction plates (22) are splined to barrel (7).
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| Illustration 11 | g00479820 |
Brake Pilot Valve (13) Port (36) Passage (40) Spring (41) Valve (42) Retainer (43) Orifice | |
When no pump oil is supplied to the travel motor, piston (27) is pushed to the left by the force of spring (26). The oil in piston chamber (38) now flows through passage (39) and passage (36). The oil flows through orifice (43) and into the valve of the motor case drain line. Piston (27) moves to the left. Friction plates (22) and separator plates (23) are held together against housing (37). The rotation of the travel motor stops. Drive shaft (1) engages the parking brake.
Orifice (43) restricts return oil flow from piston chamber (38). The restriction of the oil flow delays the application of the parking brake. The parking brake is delayed in order to give the machine time to stop. Earlier wear and/or damage to the machine could result if the machine stayed in motion.
Prior to the operation of the travel motor, oil flows through port (13). The oil pressure opens valve (41). The oil then flows through passages (36) and (39) to piston chamber (38). Brake piston (27) moves to the right against the force of spring (26). The oil that is holding friction plates (22) and separator plates (23) together is released. The release of the oil pressure allows barrel (7) and drive shaft (1) to turn.
Displacement Change Valve
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| Illustration 12 | g00479840 |
Travel Motor (partial view) (1) Drive shaft (3) Piston (4) Swashplate (9) Check valve (10) Check valve (17) Piston (34) Displacement change valve (44) Piston chamber (45) Piston chamber (46) Passage (47) Passage (48) Port (49) Passage (50) Port (51) Port | |
Large Displacement Change Operation
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| Illustration 13 | g00479883 |
Travel Motor (partial view) (3) Piston (4) Swashplate (9) Check valve (10) Check valve (17) Piston (34) Displacement change valve (44) Piston chamber (45) Piston chamber (46) Passage (47) Passage (48) Port (49) Passage (50) Port (51) Port (52) Passage (53) Passage (54) Passage (55) Adapter (56) Spring (57) Spool (58) Passage | |
When the travel speed control switch is placed in the LOW position, the travel speed solenoid valve is not energized. Pilot oil does not flow to port (48) of displacement change valve (34). The force of spring (56) moves spool (57) to the left. Spool (57) moves to the left until the spool comes in contact with adapter (55) .
Pump oil from port (51) flows through the following components: check valve (10), passage (49), passage (58) and passage (47). The oil then flows to piston chamber (45). The oil moves piston (3) upward. Swashplate (4) turns in order to increase the angle.
The oil in piston chamber (44) drains to the tank through the following passages: passage (46), passage (52), passage (53) and passage (54) .
The motor holds the swashplate in the maximum angle position.
Small Displacement Change Operation
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| Illustration 14 | g00479885 |
Travel Motor (partial view) (3) Piston (4) Swashplate (9) Check valve (10) Check valve (17) Piston (34) Displacement change valve (44) Piston chamber (45) Piston chamber (46) Passage (47) Passage (48) Port (49) Passage (50) Port (51) Port (54) Passage (56) Spring (57) Spool (58) Passage (59) Passage (60) Passage | |
When the travel speed control switch is placed in the HIGH position, the travel speed solenoid valve is energized. If the pump delivery pressure is below a certain level, pilot oil flows to port (48) of displacement change valve (34). Pilot oil moves spool (57) to the right against the force of spring (56). Passage (58) closes and this opens passage (60) .
Pump oil flows through passages (49), (60) and (46). The oil then flows to piston chamber (44). The oil moves piston (17) upward. Swashplate (4) turns in order to decrease the angle.
The oil in piston chamber (45) drains to the tank through passages (47), (59) and (54) .
The motor holds the swashplate in the minimum angle position.