CB10 Vibratory Asphalt Compactor Propel System (Solid Drum) Hydraulic Schematic (Propel System) Caterpillar


Hydraulic Schematic (Propel System)
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CB10 Vibratory Asphalt Compactor Propel System (Solid Drum) [M0114506]
HYDRAULIC SYSTEM
CB10 Vibratory Asphalt Compactor Propel System (Solid Drum) General Information (Propel System)
CB10 Vibratory Asphalt Compactor Propel System (Solid Drum) Hydraulic Schematic (Propel System)


Illustration 1g06619064
Propel Hydraulic Schematic in Neutral and Low Speed With Parking Brake on
(1) Solenoid "A"
(2) Solenoid "B"
(3) Combination valve (for port "B")
(4) Charge orifice
(5) Interlock valve
(6) To vibratory pump case drain port"L1"
(7) Propel pump
(8) Servo piston
(9) Pump rotating group
(10) Combination valve (for port "A")
(11) Parking brake
(12) Control valve
(13) Rear propel motor
(14) Flushing spool
(15) Flushing relief valve
(16) Parking brake
(17) Front propulsion motor
(18) Control valve
(19) Flushing spool
(20) Flushing relief valve
(21) Oil cooler
(22) Return manifold
(23) Shift valve
(24) To charge relief valve
(25) From fan motor
(26) Charge filter

The above illustration shows the propulsion hydraulic system under the following conditions:

  • The propel lever is in the NEUTRAL position.

  • The parking brake status is set to on.

  • The propel mode is set to low.

The propel circuit consists of a hydrostatic-drive circuit for the front drum and the rear drum. The closed-loop circuit has single pump (7) and two motors (13) and (17), one for each drum.

Displacement of rotating group (9) in the pump is electronically controlled. The machine ECM calculates the desired speed and energizes the appropriate pump control solenoid to move the machine at the desired speed. When the propel lever is in the NEUTRAL POSITION, the swashplate in the rotating group is at zero angle. The swashplate is also at zero angle if the machine ECM has disabled the propel system. In either of these cases, the rotating group does not produce flow.

The charge pump provides hydraulic oil to drive the fan system. Oil from fan motor (25) flows through charge filter (26) to provide charge oil to the propel system when the engine is running. Charge oil from the charge filter flows to port "Fe" of propel pump (7). Charge oil also flows to shift valve (23), and to charge relief valve (24), which is installed in the vibratory pump. Inside the propel pump, charge oil flows to interlock valve (5), charge orifice (4), and the combination valves.

Charge pressure is maintained by the charge relief valve in the vibratory pump. When charge pressure reaches 3000 ± 300 kPa (435 ± 43 psi), the oil pressure overcomes the spring force and the charge relief valve opens. This action directs charge pump flow into the case drain of the vibratory pump, and forces oil through charge orifice (4) in propel pump (7).

When the parking brake switch is in the ON position or the machine ECM has disabled the propel system, solenoid in interlock valve (5) is not energized. This solenoid prevents charge oil from reaching pump control solenoids (1) and (2) and from reaching the parking brake piston cavities. Under these conditions, the brake piston cavities and both sides of servo piston (8) are open to the pump case. The servo piston holds the swashplate in the rotating group at zero angle. The springs that are acting against the brake pistons engage parking brakes (11) and (16).

As long as the solenoid in interlock valve (5) is not energized, the swashplate in rotating group (9) remains in the zero angle position. In this case, charge pressure is blocked at the interlock valve and the servo chambers of the pumps are vented to the pump case. These conditions are maintained, regardless of the position of the propel lever.

Charge pressure acts against the makeup valves in each combination valve (3) and (10). If the pressure in either the forward loop or the reverse loop falls below charge pressure, the makeup valves open. In this case, charge oil flows into the loop.

Since the pressure in the forward circuit is equal to the pressure in the reverse circuit when the machine is not moving, flushing spool (14) and (19) in each propel motor is in the center position. In this case, the spool prevents flushing oil from flowing into the case drains of the motors.



Illustration 2g06619085
Hydraulic Schematic With Solenoid "A" Energized, in Low Speed, and With Parking Brake Off
(1) Solenoid "A"
(2) Solenoid "B"
(3) Combination valve (for port "B")
(4) Charge orifice
(5) Interlock valve
(6) To vibratory pump case drain port "L1"
(7) Propel pump
(8) Servo piston
(9) Pump rotating group
(10) Combination valve (for port "A")
(11) Parking brake
(12) Control valve
(13) Rear propel motor
(14) Flushing spool
(15) Flushing relief valve
(16) Parking brake
(17) Front propulsion motor
(18) Control valve
(19) Flushing spool
(20) Flushing relief valve
(21) Oil cooler
(22) Return manifold
(23) Shift valve
(24) To charge relief valve
(25) From fan motor
(26) Charge filter

The above illustration shows the propulsion hydraulic system under the following conditions:

  • The parking brake status is set to off.

  • The propel mode is set to low.

  • The seat is facing the front of the machine and the propel lever is in the forward range. Alternatively, the propel lever is in the reverse range while the operator station is facing the rear of the machine.

Charge oil flows to combination valves (3) and (10) and to interlock valve (4). With the parking brake switch in the OFF position, the interlock valve directs charge oil into the piston cavities of parking brakes (11) and (16). The charge pressure in the parking brake piston cavities overcomes the spring force, and the parking brakes release. At the same time, charge oil is also routed to the pump control spool.

When the propel mode is set to low, shift valve (23) is not energized. In this case, each piston in the rotating groups of propel motors (13) and (17) receive supply oil. Under these conditions, the motors operate at low speed and full torque.

When the machine ECM determines that the machine should be moving, the ECM energizes solenoid "B" (1). In this case, the solenoid directs charge oil into the "X1" side of servo piston (8). The pressure in this side of the servo piston causes the pump servo to move. This movement changes the angle of the swashplate in rotating group (9). The stronger the signal to the solenoid, the greater the swashplate angle, and therefore, the greater the oil flow from the propel pump.

As the swashplate moves, the feedback linkage tends to move the pump solenoid spool back to neutral through an internal feedback spring. This action prevents the servo piston from tilting the swashplate too far.

Supply oil from rotating group (9) flows to the following locations:

  • Combination valve (3) for port "B"

  • Port "MB" on propel pump (7)

  • Port "B" of front propel motor (17)

  • Port "A" of rear propel motor (13)

The pressure differential between the two sides of propel motors (13) and (17) causes the motors to turn. After turning the motors, oil at a reduced pressure flows to the following locations:

  • Flushing spool (14) and (19) in each motor

  • Port "A" of front propel pump (7)

  • Port "MA" on propel pump (7)

Inside propel pump (7), supply oil from the rotating group acts against the relief valve in combination valve (3) for port "B". As long as the pressure in this circuit is greater than charge pressure, the makeup valve in the combination valve remains seated. As long as the supply pressure is less than relief pressure, the relief valve in the combination valve remains closed.

If pressure in the return loop falls below charge pressure, the makeup valve in combination valve (10) for port "A" opens. In this case, charge oil flows into the low-pressure side of the loop. When pressure in the low-pressure side of the loop rises above charge pressure, the makeup valve closes.

Loop flushing occurs in rear propel motor (13) and front propel motor (17). In each motor, supply circuit oil acts against one side of the flushing spool. Return circuit oil acts against the opposite side of each flushing spool. In both motors, the higher-pressure oil moves the flushing spool. This movement allows return circuit oil to flow across the spool to the flushing relief valve.

Anytime the pressure in the return circuit is greater than the setting of a flushing relief valve, the corresponding flushing relief valve opens. In this case, oil from the return circuit flows through an orifice and into the motor case drain line.

The pressure setting of the flushing relief valve is less than the pressure setting of the charge relief valve. This fact ensures that oil is sent through the motor case drain under normal operating conditions. The flushing relief valve will stop flushing flow if the charge pressure is less than the setting of the flushing relief valve. This fact ensures that flow through the flushing orifice does not cause charge pressure to decrease to the point at which charge pressure becomes less than the brake release requirement.



Illustration 3g06619095
Hydraulic Schematic With Solenoid B Energized, in High Speed, and With Parking Brake Off
(1) Solenoid "A"
(2) Solenoid "B"
(3) Combination valve (for port "B")
(4) Charge orifice
(5) Interlock valve
(6) To vibratory pump case drain port "L1"
(7) Propel pump
(8) Servo piston
(9) Pump rotating group
(10) Combination valve (for port "A")
(11) Parking brake
(12) Control valve
(13) Rear propel motor
(14) Flushing spool
(15) Flushing relief valve
(16) Parking brake
(17) Front propulsion motor
(18) Control valve
(19) Flushing spool
(20) Flushing relief valve
(21) Oil cooler
(22) Return manifold
(23) Shift valve
(24) To charge relief valve
(25) From fan motor
(26) Charge filter

The above illustration shows the propulsion hydraulic system in the following conditions:

  • The parking brake status set to off

  • The propel mode set to high

  • The seat is facing the front of the machine and the propel lever is in the reverse range. Alternatively, the propel lever is in the forward range while the operator station is facing the rear of the machine.

Rotating group (9) directs oil out port "A" on propel pump (7). This oil flows to the port "A" of rear propel motors (13) and port "B" of the front propel motor. The motors rotate, and reduced-pressure oil returns to rotating group (9) through port "B" of the propel pump. On each motor, the flushing spools and the flushing relief valves direct return oil into the case drain of the motor. The relief valve in combination valve (10) for port "A" limits the maximum pressure in the supply circuit. The makeup valve in combination valve (3) for port "B" allows charge oil to enter the return circuit to replenish oil lost to loop flushing.

When the propel mode is set to high or roading, shift valve (23) is energized and the valve shifts. The position of the shift valve allows charge oil to act on control valve (18) in front propel motor (17). Under these conditions, the control valve in the front motor shifts. In this case, only half of the pistons in the rotating group receive supply oil. The remaining pistons are connected to the outlet side of the motor. As a result, the motor operates with higher speed but lower torque.

When the propel mode is set to high or roading, the rear propel motor continues to operate in the low speed mode. The combination of modes between the front and rear motors provides better gradability and braking performance.

Information System:

CB10 Vibratory Asphalt Compactor Propel System (Solid Drum) Electrical Schematic (Propel System)
CB10 Vibratory Asphalt Compactor Propel System (Solid Drum) Piston Motor (Drum Propel)
CB10 Vibratory Asphalt Compactor Propel System (Solid Drum) Piston Pump (Propel)
CB10 Vibratory Asphalt Compactor Propel System (Solid Drum) Propel System Components
CB10 Vibratory Asphalt Compactor Propel System (Solid Drum) Operator Controls (Propel System)
CB10 Vibratory Asphalt Compactor Propel System (Solid Drum) General Information (Propel System)
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