Introduction

Reference: For Specifications with illustrations, refer to the Specifications for the CB-534 Vibration System, Form No. KENR2424. If the Specifications in Form No. KENR2424 are not the same as listed in the Systems Operation and the Testing And Adjusting, look at the print date on the back cover of each book. Use the Specifications listed in the book with the latest date.

General Information

Vibration Circuit Schematic
(1) Hydraulic motor for rear drum. (2) Vibration mode solenoid valve. (3) Hydraulic tank. (4) Hydraulic filter. (5) Hydraulic motor for front drum. (6) Vibration pump group.

The vibration system is a hydrostatic system. The main components of the system are hydraulic tank (3), hydraulic filter (4), vibration pump group (6), front and rear hydraulic motors (1) and (5) and vibration mode solenoid valve (2).

Hydraulic Tank And Filter Location
(3) Hydraulic tank. (4) Hydraulic filter.

Hydraulic filter (4) is installed horizontally in hydraulic tank (3). Oil for the propulsion, vibration, steering and brake circuits passes through this filter. All of the return line oil enters the tank. Unless the filter cartridge is plugged or the oil is cold, all of the oil goes through the filter cartridge. Direction of flow is from the interior to the exterior of the filter and out towards the different circuits.

Pump Group Location
(7) Vibration pump section. (8) Propulsion pump section.

A dual circuit pump is used for both vibration and propulsion functions. Both sections of the pump are for closed circuit operation. They are independent of one another. They are of the axial piston swashplate design.

The vibration pump section is the variable type but used as a fixed displacement pump. The propulsion pump section is the variable displacement type. All the output (horse power) of the engine in the compactor is used to turn this pump group and the gear-type steering pump.

Vibration Pump

Dual Pump Group
(1) Vibration pump. (2) Propulsion pump. (3) Splitter box.

The vibration pump is part of the pump group installed at the rear of the engine. It is driven through splitter box (3). The rpm of the vibration pump is identical to the propulsion pump. The rpm of each pump under load is approximately 1.47 times the engine rpm. Any change in engine rpm will, at the same time, change the rpm of the pumps.

Vibration Pump
(4) Main case. (5) Cup. (6) Shim. (7) Direction control valve. (8) Hydraulic regulator. (9) Port plate. (10) Closed circuit loop line port. (11) Drive shaft. (12) Bearing housing. (13) Swashplate. (14) Spring washer. (15) Cylinder barrel. (16) Piston (one of nine). (17) O-ring. (18) Head. (19) Closed circuit loop line port. (20) Passage. (21) Charge pump.

Charge pump (21) has an independent gravity-fed oil supply line from the hydraulic tank. When the engine is running, shaft (11), cylinder barrel (15) and charge pump (21) drive gears turn. There are nine cylinders and pistons in the cylinder barrel. The remainder of the components of the pump are fastened to or are held by the pump housing.

Swashplate And Barrel Assemblies
(5) Cup. (13) Swashplate. (14) Spring washers. (15) Cylinder barrel. (16) Piston.

In the position shown, swashplate (13) is at its maximum position. Shaft (11) turns cylinder barrel (15). Each piston (16) follows the angle of the swashplate. As the pistons follow the angle of the swashplate, they move in and out of the cylinders in the cylinder barrel. As the piston moves out of the cylinder, oil is supplied behind it. This oil is delivered under pressure from charge pump (21) through passage (20).

Oil that is pushed ahead of the piston goes through outlet passages of port plate (9) and leaves the pump through loop line ports (10) and (19). Port plate (9) and cylinder barrel (15) valve surfaces are spherical in shape. Inlet oil is sealed from outlet oil by a metal-to-metal seal between the spherical faces of the port plate and cylinder barrel. On the other face of the port plate, the seal is made with the face of head (18). O-ring (17) seals head (18) from main case (4). Since outlet pressures can be as high as 35 000 kPa (5100 psi), the sealing faces must be made with precision. No damage is permissible. Protection must be given to these faces during disassembly and assembly.

Spring Assembly
(5) Cup. (6) Shims. (14) Spring washer. (15) Cylinder barrel.

Spring washers (14) and shims (6) are held in place on swashplate (13) by cup (5). The compression of the springs is the force which holds the face of the cylinder barrel against port plate (9) and head (18).

The length of stroke of the pistons is changed when swashplate (13) is turned around its axis. At the neutral position, piston stroke and oil delivery is zero. At maximum inclination of ± 15°, piston stroke is at its maximum.

Charge Pump

Charge pump (21) delivers cooled filtered oil from the tank to the fixed displacement pump. It also provides hydraulic piloting of the hydraulic regulator and the vibration mode valve group. The charge pump also compensates for internal oil leakage inside the closed circuit loop lines.

Charge And Main Line Relief Valves

Charge And Main Line Relief Valves
(22) Main line relief valve. (23) Main line relief valve. (24) Charge pump circuit relief valve.

Pilot and loop circuit return line pressure are limited to 2000 kPa (290 psi) by relief valve (24).

Boost Pump Circuit Relief Valve (Shown Open)
(25) Adjustment screw. (26) Locknut. (27) Spring. (28) Valve. (29) Inlet passage. (30) Outlet passage to tank.

Oil from charge pump (21) enters the valve through inlet (29). When circuit oil pressure is less than the relief valve setting, the force of spring (27) keeps valve (28) closed. When the oil pressure reaches the valve setting, the valve will move and allow oil to flow through outlet passage (30) into the tank return line.

Main Line Relief Valves
(31) Passage. (32) Valve surface. (33) Valve surface. (34) Pressure relief valve section. (35) Spring. (36) Nut. (37) Valve surface. (38) Dump valve section. (39) Passage. (40) Spring. (41) Passage. (A) Passage. (B) Passage.

The maximum working pressure of each loop line of the closed circuit is limited to 35 000 kPa (5100 psi) by two relief valves. There is one for each loop line. These valves are the indirect-acting type. They limit the main circuit pressure to specific values which can be changed by adjusting the valve setting. Each indirect-acting valve group is made up from two valves. They are dump valve section (38) and pressure relief valve section (34).

Oil from the vibration pump enters the valve group through passage (A). It passes through passage (31) in center of dump valve (38) and into the chamber of spring (40). The pressure of the oil acts against pressure relief valve (34). The force of spring (35) keeps valve (34) closed until oil pressure in the loop line reaches relief pressure.

Dump valve (38) also remains closed. The pressure of the oil acts on both dump valve surfaces (33) and (37). Surface (33) is larger than surface (37), therefore the force exerted on this surface is greater. The combination of this force and the force of valve spring (35) will keep the dump valve closed. When the pressure of the oil reaches the relief valve setting, relief valve (34) will open. Oil in the chamber of spring (40) passes around relief valve (34), through passage (41), and into the return line of the loop circuit.

When there is a drop in oil pressure in the chamber of spring (40), only the force of the spring is acting against dump valve (38). The force acting on the opposite face of the valve is greater, therefore the valve will open. Delivery line oil from inlet passage (A) can now go through passage (39) into the return line of the closed circuit.

This valve group also has a secondary function. It acts as a check valve for the charge pump circuit. When the vibration mode is switched off, only the charge pump is delivering oil. Charge pump oil can only enter the loop lines of the closed circuit by passing through the dump valve section of the main relief valve. Boost circuit relief valve limits the line pressure to 2000 kPa (290 psi). Pressure oil arriving at passage (B) acts on dump valve surface (32). The force acting on this surface is greater than the force exerted by spring (40). Dump valve (38) opens. Charge pump oil passes around valve (38) into passage (A) and loop lines of the closed circuit.

When the vibration mode is switched on, the relief valves on the pump delivery and return lines will be closed. The dump valve section of the relief valve on the return line of the circuit will open. This allows charge pump oil into the return line to compensate for oil loss through internal leakage.

Hydraulic Regulator And Direction Control Valve

2EG1-2EG170, 2YF1-2YF27

Hydraulic Regulator And Direction Control Valve Location
(7) Direction control valve. (8) Hydraulic regulator.

Swashplate movement is controlled by hydraulic regulator (8) and direction control valve (7). When a solenoid of the direction control valve is energized, pressure oil is allowed to pass through the valve and pilot the hydraulic regulator.

Vibration On/Off Contactors On Propulsion Control Lever
(42) Propulsion control lever. (43) Guide. (44) Electric contact breakers.

Energizing the direction control valve of the vibration pump is done by the movement of propulsion control lever (42). Two electric contactor breakers (44) are mounted on guide (43) of the control lever.

When the vibration on/off contactor is in the ON position, movement of the propulsion control lever either fully forwards or backwards will trip one of the electric contact breakers. Current will then pass through the circuit and energize one of the solenoids of the direction control valve.

Direction Control Valve
(45) Spring. (46) Valve spool. (47) Solenoid.

As soon as current is supplied to either solenoid (47), the solenoid will energize the valve. The force which is created will move spool (46). Charge pump pressure oil will pass across the spool out into the pilot line to the hydraulic regulator.

As soon as the propulsion lever is moved to the neutral position, the contact breaker will open and stop current flow to solenoid (47). The force of either spring (45) will move spool (46) back towards the neutral position. The forces of springs (45) are identical. They balance one another and maintain the spool in the neutral position.

Hydraulic Regulator
(48) Piston. (49) Piston chamber. (50) Displacement reduction stop. (51) Displacement reduction stop adjuster.

When direction control valve (7) is energized, pressure oil passes through a 0.80 mm (.031 in) orifice. This orifice is in the inlet port of hydraulic regulator (8). The orifice makes the movement of the regulator piston smooth and progressive. Pressure oil then passes into piston chamber (49) and pushes piston (48). The piston moves until it reaches the end of its stroke. The piston stroke is controlled by stop (50).

As the piston moves, it inclines the swashplate of the pump. The movement stops when the swashplate is at its maximum angle.

Moving the propulsion control lever back to the neutral position stops the electric current flow to the direction control valve. The direction control valve will then stop the flow of pilot line oil to hydraulic regulator (8). Springs in piston chamber (49) will bring piston (48) back to its neutral position. The swashplate will also return to its neutral position. Pilot oil which is in chamber (49) is forced back through the orifice on the return line. This makes the return action of the regulator piston smooth and progressive. It also avoids any sudden jerking motion when the compactor is stopped.

2EG171-UP, 2YF28-UP

Hydraulic Regulator And Direction Control Valve Location
(1) Direction control valve. (2) Hydraulic regulator.

Swashplate movement is controlled by hydraulic regulator (2) and direction control valve (1). When a solenoid of the direction control valve is energized, pressure oil is allowed to pass through the valve and move the hydraulic regulator.

Engine Compartment
(3) Pressure switch, forward vibration control. (4) Pressure switch, reverse vibration control.

The vibration direction control valve on the vibration pump is actuated by pressure switches (3) and (4).

When the vibration on/off switch is in the ON position, voltage is available at pressure switches (3) and (4). When the propel lever is moved forward, the pilot oil pressure to the hydraulic regulator and pressure switch (3) increases. When the pressure reaches 1025 kPa (150 psi), pressure switch (3) closes. Electric current now flows to the forward vibration solenoid.

Direction Control Valve
(5) Spring. (6) Valve spool. (7) Solenoid.

As soon as current is supplied to either solenoid (7), the solenoid will energize the valve. The force which is created will move spool (6). Charge pump pressure oil will pass across the spool out into the pilot line to the hydraulic regulator.

When the propel lever is moved back to the neutral position, the pilot pressure to the hydraulic regulator and pressure switch (3) drops below 1025 kPa (150 psi) and opens pressure switch (3). Electric current flow to solenoid (7) stops. The force of either spring (5) will move spool (6) back towards the neutral position. The forces of springs (5) are identical. They balance one another and maintain the spool in the neutral position.

Hydraulic Regulator
(8) Piston. (9) Piston chamber. (10) Displacement reduction stop. (11) Displacement reduction stop adjuster.

When the direction control vale is energized, pressure oil passes through a 0.80 mm (.031 in) orifice. This orifice is in the inlet port of the hydraulic regulator. The orifice makes the movement of the regulator piston smooth and progressive. Pressure oil then passes into piston chamber (9) and pushes piston (8). The piston moves until it reaches the end of its stroke. The piston stroke is controlled by stop (10).

As the piston moves, it inclines the swashplate of the pump. The movement stops when the swashplate is at its maximum angle.

Moving the propulsion control lever back to the neutral position stops the electric current flow to the direction control valve. The direction control valve will then stop the flow of pilot line oil to the hydraulic regulator. Springs in piston chamber (9) will bring piston (8) back to its neutral position. The swashplate will also return to its neutral position. Pilot oil which is in chamber (9) is forced back through the orifice on the return line. This makes the return action of the regulator piston smooth and progressive. It also avoids any sudden jerking motion when the compactor is stopped.

Vibration Mode Valve Group

Control Panel
(1) Cover. (2) Vibration mode selector switch. (3) Vibration on/off contactor.

Vibration mode selection is made by moving switch (2) to front, rear or dual drum vibration. When cover (1) is pushed down, contactor (3) allows electric current to flow to solenoid valve (4). The solenoid valve and mode selector valve (5) control the different vibration functions.

Vibration Mode Valve Group Location
(4) Solenoid valve. (5) Vibration mode selector valve.

The electric signal from mode switch (2) energizes one of solenoids (6), depending on the vibration mode choice. As soon as the current flows to the solenoid, it energizes the valve. The force which is created moves spool (7), compressing spring (8). Charge pump pressure oil passes through the valve to pilot valve spool (9) of selector valve (5). The oil pressure moves spool (9), compressing spring (10) at the same time.

Piloting either one side or the other of spool (9) determines whether high pressure or return line oil of the closed circuit will pass through the valve group.

Vibration Mode Valve Group
(6) Solenoids. (7) Spool. (8) Spring. (9) Spool. (10) Spring.

Vibration Motor

Vibration Motor
(1) Front cover. (2) Bearing. (3) Motor housing. (4) Retainer. (5) Spring washers. (6) Piston (one of nine). (7) Cylinder barrel. (8) Head. (9) Portplate. (10) Oil passage. (11) Bearing. (12) Shaft. (13) Shim. (14) Swashplate. (15) Cup. (16) Retraction plate. (17) Piston (one of nine). (18) Oil passage.

The front and rear drum vibration motors are identical. They are both fixed displacement type. Each motor is mounted on a side frame drum support. Th vibratory mechanism is directly driven by motor shaft (12). Each motor receives oil from the fixed displacement pump. The motors are supplied with high pressure oil in series when both drums are vibrating. When in the single drum mode, one of the motors will be held in a static position by either high or low pressure oil at its inlet and outlet ports. The other motor is driven by high pressure oil.

A change in the direction of oil flow through a motor will not change the amount of output torque from the motor shaft. Oil flow through the motor can be in either direction. A change to the direction of oil flow changes the direction of rotation of retraction plate (16) and cylinder barrel (7). The parts of the motor that turn are shaft (12), cylinder barrel (7), cup (15), spring washers (5), and piston (6). The rest of the components are fastened to head (8) or housing (3).

Oil flow from the pump goes into passage (18) in the head, through portplate (9), and into the cylinders in the barrel. When each piston reaches the position of piston (17), pressurized oil from passage (18) pushes the piston out of the barrel until the piston reaches the position of piston (6). Because of the angle between the cylinder barrel and swashplate (14), the barrel, pistons, shaft and attached parts will turn as the pistons are forced out of the cylinders.

When rotation of the cylinder barrel turns the pistons to the position of piston (6), the piston will be fully retracted. As the barrel continues to turn, the piston will be forced back into the cylinder. The oil in front of the piston will be forced out through passage (10) into the return line of the loop circuit.

Circuit Functions

Dual Drum Vibration Mode

Dual Drum Vibration Mode Circuit Diagram
(1) Hydraulic tank. (2) Suction line filter. (3) Hydraulic oil cooler. (4) Suction line. (5) Rear drum vibration motor. (6) Front drum vibration motor. (7) Closed circuit loop line for vibration in forward. (8) Charge pump circuit relief valve. (9) Main loop line relief valve. (10) Hydraulic regulator. (11) Fixed displacement pump. (12) Charge pump. (13) Vibration mode solenoid valve. (14) Vibration mode selector valve. (15) Closed circuit loop line for vibration in reverse. (16) Charge pump circuit line. (17) Main loop line relief valve. (18) Direction control valve. (19) Pilot line to direction control valve. (A), (B), (C) Vibration mode solenoid and selector valve positions.

When the vibration mode selector switch is placed in the dual drum vibration mode, solenoid valve (13) is not energized.

Oil is gravity fed from hydraulic tank (1) through filter group (2) to charge pump (12). From the charge pump, oil is supplied through line (16). The pressure in this line is limited by relief valve (8) to 2000 kPa (290 psi). Oil enters lines (7) and (15) through the check valve function of main relief valves (9) and (17). Oil also flows to vibration mode solenoid valve (13). Here the oil passage across the spool valve is blocked because the solenoid is not energized. Charge line oil also flows through pilot line (19) to direction control valve (18). Depending on the selected travel direction of the compactor, the direction control valve will become energized. This allows oil to pass through the valve spool to one of the chambers of hydraulic regulator (10).

The hydraulic regulator inclines the swashplate of pump (11). Pressure oil delivered from the pump is sent out into closed circuit loop lines (7) or (15), depending on travel direction.

If oil is sent into line (7), it flows to vibration motor (6). The pressurized oil drives the motor. Oil from the motor flows to vibration mode selector valve (14). The passage of oil across the spool of the selector valve is blocked because the valve is in the neutral position. At the same time, oil flows to vibration motor (5). Pressurized oil also drives this motor. Outlet oil from the motor flows back towards fixed displacement pump (11) through loop line (15). This line acts as the return line of the loop circuit.

Return line oil pressure is maintained by the charge circuit relief valve which is set at 2000 kPa (290 psi). The check valve section of relief valve (17) is open. This will allow oil from the charge pump circuit to enter into the motor pump return line (15), compensating for oil loss through internal leakage. The check valve function of other relief valve (9) will remain closed because pressure oil in delivery line (7) of the loop circuit is higher than charge pump circuit pressure. The main relief valve, set at 35 000 kPa (5100 psi), will only open when the circuit pressure is greater than its setting. When open, it allows oil to pass from the closed circuit loop line into the charge pump circuit. The oil then returns to the tank.

Oil which passes from the closed circuit into the pump and motor cases is returned to tank. Charge pump oil which passes through relief valve (8) also returns to tank. Before entering the tank, the oil passes through hydraulic oil cooler (3).

Reversing the direction of travel of the compactor will automatically reverse the flow of oil from pump (11). Oil will now flow through line (15) to motor (5). The oil then goes to motor (6) and returns to pump (11) through loop line (7). All other functions remain identical to those for forward direction of travel.

Single Drum Vibration Mode

Front Drum Only

Single Drum Vibration Mode Circuit Diagram (Front Drum)
(1) Hydraulic tank. (5) Rear drum vibration motor. (6) Front drum vibration motor. (7) Closed circuit loop line for vibration in forward. (8) Charge pump circuit relief valve. (11) Fixed displacement pump. (13) Vibration mode solenoid valve. (14) Vibration mode selector valve. (15) Closed circuit loop line for vibration in reverse. (16) Charge pump circuit line. (20) Pilot line passage. (21) Circuit line. (22) Circuit line. (A), (B), (C) Vibration mode solenoid and selector valve positions.

When the vibration selector switch is placed in front drum only mode, vibration mode solenoid valve (13) is energized. The spool in the solenoid valve will move. Block (A) of the solenoid valve moves to the position shown. Oil in line (16) can now pass across the spool valve to pilot line passage (20). Selector valve (14) is now piloted. The spool in the selector valve moves, placing block (A) of the selector valve in the position shown.

Oil flow from pump (11) passes through loop line (7) towards motor (6). After driving the motor, oil passes into line (21). This line sends the oil to motor (5) and selector valve (14). Because the spool of the selector valve has been moved, there is free passage of oil across the spool. This allows oil to pass from line (21) into loop line (15). Line (15) acts as the return line for pump (11). Motor (5) now has the same oil pressure at both inlet and outlet ports. The motor will therefore remain static. Only front drum motor (6) will turn. Relief valve (8) maintains 2000 kPa (290 psi) oil pressure in return line (15).

Reversing the direction of travel of the compactor automatically reverses the flow of oil from pump (11). Oil now flows through loop line (15) towards motor (5). It also passes through line (22) towards selector valve (14). The oil passes across the spool of the selector valve into line (21). It then flows to motors (5) and (6). There is now equal oil pressure at both the inlet and outlet ports of motor (5). The motor will therefore remain static. Motor (6) will turn. Oil passing through the motor will return to pump (11) through line (7). Relief valve (8) maintains 2000 kPa (290 psi) return line pressure.

Rear Drum Only

Single Drum Vibration Mode Circuit Diagram (Rear Drum)
(1) Hydraulic tank. (5) Rear drum vibration motor. (6) Front drum vibration motor. (7) Closed circuit loop line for vibration in forward. (8) Charge pump circuit relief valve. (11) Fixed displacement pump. (13) Vibration mode solenoid valve. (14) Vibration mode selector valve. (15) Closed circuit loop line for vibration in reverse. (16) Charge pump circuit line. (21) Circuit line. (22) Circuit line. (23) Circuit line. (24) Pilot line passage. (A), (B), (C) Vibration mode solenoid and selector valve positions.

When the vibration selector switch is placed in rear drum only mode, vibration mode solenoid valve (13) is energized. The spool in the solenoid moves. Block (C) of the solenoid valve moves to the position shown. Oil in line (16) can now pass across the spool valve to pilot line passage (24). Selector valve (14) is now piloted. The spool in the selector valve moves, placing block (C) of the selector valve in the position shown.

Oil flow from pump (11) passes through loop line (7) towards motor (6). Oil also passes through circuit line (23) towards selector valve (14). It passes across the spool of the selector valve into line (21). Oil then flows to motors (5) and (6). There is now equal oil pressure at both the inlet and outlet ports of motor (6). The motor therefore remains static. Motor (5) will turn. Oil passing through the motor will return to pump (11) through loop line (15). Relief valve (8) maintains 2000 kPa (290 psi) return line pressure.

Reversing the direction of travel of the compactor will automatically reverse the flow of oil from pump (11). Oil will now flow through loop line (15) towards motor (5). Oil also passes through line (22) where its passage is blocked at the spool of selector valve (14). After the oil passes through motor (5), it flows towards motor (6) and the selector valve through circuit line (21). Oil passes across the valve spool towards loop line (7). There is now equal oil pressure at both the inlet and outlet ports of motor (6). The motor will remain static. Relief valve (8) maintains 2000 kPa (290 psi) return line pressure.