CB-534D, CB-534D XW and CB-564D Vibratory Asphalt Compactors Vibratory System Piston Pump (Vibratory) Caterpillar


Piston Pump (Vibratory)
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1.1. Pressure Override Relief Valve
2.2. CB-534D
3.2. CB-564D
4.1. Combination Valves
5.2. CB-534D
6.2. CB-564D
7.2. High Pressure Relief Valve
8.2. Makeup Check Valve
9.1. Charge Relief Valve
10.1. Servo Piston Assembly
11.1. Pump Control



Illustration 1g00688716

(1) Splined shaft

(2) Servo housing

(3) Servo piston

(4) Cylinder barrel

(5) Housing

(6) Control valve

(7) Port plate

(8) Swashplate

(9) Spring assembly

(10) Piston (one of nine)

(11) Main circuit passage

(12) Main circuit passage

(13) Passage (charge oil circuit)

(14) Head

(15) Relief valve

When the engine is operating, the shaft (1) and the barrel (4) are rotating. There are nine pistons (10) in the barrel assembly (4). The port plate (7) and the swashplate (8) are fastened to the housing (5) or held by the housing (5). This housing (5) does not rotate. The spring assembly (9) keeps force on barrel (4) in order to provide a high pressure seal between the barrel assembly (4) and the port plate (7). When the barrel assembly (4) is rotating, each piston (10) follows the angle of the swashplate. If the swashplate angle is at zero, the pistons do not move in and out of the barrel assembly. There is no oil flow. The charge oil from the steering pump will maintain the oil pressure in the pump.

The charge oil will perform the following functions:

  • keep the barrel assembly full of oil.

  • lubricate the pump components.

  • replace the normal internal loss of oil due to leakage.

  • cool the pump.

The position of swashplate (8) is controlled by the control valve (6) and the servo piston (3). The control valve (6) receives electrical current from the vibratory switch. The vibratory switch is located on the handle of the propel control. The vibratory switch routes the control oil in order to activate the servo piston (3). The servo piston (3) controls the angle of the swashplate (8). The position of the swashplate (8) determines the direction of the flow of the two main circuit passages (11) and (12) .

The angle of the swashplate (8) is in the maximum position. This angle is shown in the above illustration. As the pistons (10) follow the swashplate, the pistons move in and out of the cylinder barrel (4). As the pistons (10) move out of the cylinder, the oil is supplied to the back of the pistons. This oil is supplied under pressure from the charge circuit through passage (13) .

Oil which is pushed ahead of the pistons (10) goes through the outlet passages of port plate (7). The oil will then leave the pump through the circuit line passage (11) or (12). The valve surfaces of the port plate (7) and the cylinder barrel (4) are spherical in shape. The inlet oil is sealed from the outlet oil by a metal-to-metal seal between the spherical faces of the port plate (7) and the cylinder barrel (4). The seal which is created between the port plate (7) and the cylinder barrel (4) is called a precision seal.




Illustration 2g00592130

Spring Assembly

(4) Cylinder barrel

(9) Spring

(16) Shim

(17) Cup

The spring assembly (9) and the shims (16) are held in place on the swashplate (8) by the cup (17). Compression of the springs will hold the face of the cylinder barrel (4) against the port plate (7) and the head (14) .

The length of the stroke of the pistons (10) is changed when the swashplate (8) is turned about the axis. At the neutral position, the piston stroke and the oil delivery is zero.

Pressure Override Relief Valve




Illustration 3g00592689

Pressure Override Relief Valve

(1) Adjustment screw

(2) Locknut

(3) Spring

(4) Passage

(5) Valve

(6) Passage

(7) Piston

(8) Chamber

(9) Passage

(10) Slug

(11) Passage

Oil from the high pressure side of the closed circuit enter the POR valve at either passage (9) or (11). Passage (9) or (11) is dependent on the side of the closed circuit which is pressurized. Slug (10) will move upward if the high pressure is in passage (11). Slug (10) will move downward if the high pressure is in passage (9) .

When the system pressure equals the setting for the pressure override valve, this pressure will cause the piston (7) and the valve (5) to move against the spring (3). Passage (4) opens for the pressure oil from the charge pump into passage (6). The oil leaves passage (6) and leaves for the drain. After the charge pump pressure drains, the centering springs will reduce the angle of the swashplate.

While the vibratory system is operating and the system is under peak load, the valve (5) modulates the holding charge pressure on the swashplate. The stroke of the swashplate angle is held in a position in order to supply makeup oil for system leakage. The swashplate angle also maintains the circuit pressure at the POR setting until the load is reduced.

During the start-up of the vibratory system, the POR valve limits the rate for the stroke of the pump swashplate. The POR valve reduces the power requirements of the oil in the closed circuit. The POR valve eliminates the unnecessary heating of the oil in the closed circuit. The POR valve does not protect the pump or the motor during moments of spikes.

The pressure from the POR is checked at the test port of the main loop on the vibratory pump. The pressure can be adjusted by loosening the locknut (2) and adjusting the screw (1) .

CB-534D

In the dual amplitude mode and the five amplitude mode, the maximum working pressure of each line in the closed circuit is limited to 33000 ± 700 kPa (4786 ± 102 psi). In the versa vibe mode, the maximum working pressure of each line in the closed circuit is limited to 38000 ± 2000 kPa (5512 ± 290 psi). The orifice for the POR meters the charge oil from the control circuit. The shuttle valve receives the pilot oil from the high pressure side of the closed circuit. The pilot oil will shift the shuttle valve. The pilot oil allows the high pressure pilot oil to act on the POR valve (1). The POR valve (1) varies the pump swashplate angle in order to limit the maximum pressure in the ports of the main loop in the vibratory circuit.

CB-564D

In the dual amplitude mode and the five amplitude mode, the maximum working pressure of each line in the closed circuit is limited to 38000 ± 2000 kPa (5512 ± 290 psi). The orifice for the POR meters the charge oil from the control circuit. The shuttle valve receives the pilot oil from the high pressure side of the closed circuit. The pilot oil will shift the shuttle valve. The pilot oil allows the high pressure pilot oil to act on the POR valve (1). The POR valve (1) varies the pump swashplate angle in order to limit the maximum pressure in the ports of the main loop in the vibratory circuit.

Combination Valves

CB-534D

This valve is a direct acting valve that limits the main circuit pressure to a specified value. The maximum working pressure of each loop line of the closed circuit is limited to 33500 ± 1700 kPa (4859 ± 247 psi) by these valves. This value can be changed by adjusting the valve setting.

The combination valves are designed to provide the following three functions:

  • High pressure relief valve

  • Makeup check valve

CB-564D

This valve is a direct acting valve that limits the main circuit pressure to a specified value. The maximum working pressure of each loop line of the closed circuit is limited to 40000 ± 2000 kPa (5802 ± 290 psi) by these valves. This value can be changed by adjusting the valve setting.

The combination valves are designed to provide the following three functions:

  • High pressure relief valve

  • Makeup check valve

High Pressure Relief Valve




Illustration 4g01239676

CB-564D Combination Valve

(18) Locking cap

(19) Conical spring

(20) Collar

(21) Spindle

(22) Spring

(23) Collar

The high pressure relief valve functions in order to protect the circuit from high pressure spikes. The valve also protects against damage to the circuit components if the POR valve malfunctions. Oil from the vibratory pump flows through the relief valve (15) at passages (A). The high pressure oil enters passage (A). The high pressure oil acts on the collars (20) and (23). The force of the spring (22) keeps the valve closed until the oil pressure in the high pressure side of the main loop circuit reaches relief pressure. When the relief pressure is reached, the pressure causes the spindle (21) to movedownward. The spindle compresses the spring (22). The relief oil flows from the high pressure side to the low pressure side of the main circuit. The oil flows through the gap between the spindle (21) and the collar (23). The arrows show this flow in illustration 4. The high pressure oil enters the low pressure side of the main circuit until the force of the spring (22) seats the spindle (21) against the collar (23) .

Makeup Check Valve




Illustration 5g01239715

CB-534D Combination Valve

(18) Locking cap

(19) Conical spring

(20) Collar

(21) Spindle

(22) Spring

(23) Collar

(A) Passage

The combination valve has a second function. The valve acts as a makeup valve for the closed circuit. If the pressure in passage (A) drops below the charge pressure, charge oil fills the closed circuit. Oil from the vibratory pump flows through the relief valve (15) at the passages (A). The force of the spring (19) and the oil pressure in passage (A) keep the collar (23) closed. Charge pressure acts on the bottom of collar (23) and the spindle (21). When the oil pressure in passage (A) drops below the charge pressure, collar (23) and the spindle (21) move upward compressing the spring (19) .

Charge Relief Valve

The charge oil is supplied by the steering pump. The charge oil performs the following functions:

  • cool the main circuit.

  • flush the main circuit.

  • cool the pump case.

  • flush the pump case.

  • cool the motor case.

  • flush the motor case.

The charge oil replenishes the lost oil in the main circuit, and the charge oil supplies control oil for the vibratory pump. The charge pressure is limited by the charge relief valve. The pressure of the charge relief valve is checked at the test port.

Servo Piston Assembly




Illustration 6g00940431

Section View Of The Vibratory Pump

(1) Splined shaft

(2) Bearing

(3) Pump housing

(4) Swashplate

(5) Joint pin

(6) Servo housing

(7) Servo piston

(8) Cylinder barrel

(9) Solenoid valve




Illustration 7g00940432

Section View Of The Servo Piston

(6) Servo housing

(7) Servo piston

(10) Locknut

(11) Stroke limiter screw

(12) Piston rod

(13) Springs (centering)

The servo control assembly controls the angle of the swashplate (4). Swashplate (4) is part of the vibratory pump. The servo housing (6) is an integral part of the vibratory pump. The servo housing (6) contains the servo piston (7) .

The charge circuit supplies control oil to the solenoid control valve (9). The solenoid control valve is located on the pump housing (3). The solenoid control valve (9) controls the servo piston (7) by directing the control oil that enters the servo housing (6). The linear movement of the servo piston (7) mechanically controls the angular movement of the swashplate (4) with the joint pin (5) .

The flow of the pump is zero when the swashplate angle is zero. The swashplate angle is zero when the servo piston (7) is in the neutral position. The servo piston (7) returns to the neutral position when the solenoid control valve is not energized. The servo piston (7) is mechanically centered by the centering springs (13). The center position of the servo piston (7) can be adjusted by loosening the locknut (10) and turning the piston rod (12) .

The maximum flow of the pump is controlled by the servo piston (7). The flow of the pump is at the maximum when the swashplate (4) is at the maximum angle. The maximum swashplate angle is controlled by limiting the travel of the servo piston (7). The travel of the servo piston is adjusted by turning the stroke limiter screws (11). There are two stroke limiter screws. One screw for each direction of travel of the servo piston (7). The stroke limiter screws (11) are located in each end of the servo housing (6) .

Pump Control




Illustration 8g00940486

Control Valve

(1) Spring

(2) Solenoid

(3) Spool

The control valve is attached to the vibratory pump. The valve is a three-position solenoid. The valve is a four-way directional control valve. The control valve directs control oil to the servo circuit of the vibratory pump.

When current is supplied to either solenoid (2), the solenoid moves the valve spool (3). The controlled oil passes across the valve spool (3). The oil then goes out through the passage to the hydraulic servo.

When the vibratory circuit is not activated, there is no current flow to either of the solenoids (2). The force of the springs (1) moves valve spool (3) to the neutral position. The force of each spring (1) is identical. The springs balance each other. The springs maintain the center position of the valve spool (3) .

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