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| Illustration 1 | g00657348 |
(1) Frame leveling cylinder (2) Load control valve (3) Control valve (4) Differential lock cylinder (5) Control valve (auxiliary) (6) Control valve (tilt) (7) Control valve (boom extend/retract) (8) Control valve (boom raise/lower) (9) Manifold valve (inlet) (10) Solenoid valve (11) Solenoid valve (12) Solenoid valve (13) Solenoid valve (differential lock) (14) Line (brake system) (15) Solenoid valve group (16) Steering hand metering unit (17) Filter (18) Tank (19) Load sensing line (20) Pump (21) Compensating cylinder (22) Bank valve (23) Load control valve (24) Boom extend cylinder (25) Load control valve (26) Boom raise cylinder (27) Compensating valve (28) Load control valve (29) Tilt cylinder (30) Rotation cylinder (31) Manifold and relief valve (32) Pilot valve (joystick) | |
Pump (20) is a variable displacement axial piston type. The output of pump (20) is controlled by maximum implement pressure, or steering pressure.
Bank valve (22) consists of manifold valve (inlet) (9), four implement control valves, and manifold with relief valve (31). The first three control valves control the boom functions and the work tool functions. Control valves (6), (7), and (8) are operated by the pilot oil pressure. Control valve (5) controls the auxiliary functions of work tools. The control valve is operated by a solenoid. All the control valves and the auxiliary valve are operated by joystick (32). A load sensing system of resolver valves ensures that the highest load pressure controls the hydraulic pump output via the pump load sense line (19) .
Manifold valve (9) contains a priority valve which provides oil flow to the steering system.
Note: For additional information on the steering system and the hydraulic pump, refer to Service Manual, SENR5842.
Auxiliary control valve (5) controls oil flow to the hydraulic quick couplers on the boom head. The quick couplers can be connected to a work tool such as a rotation cylinder (30) .
Control valve (6) for the coupler tilt is connected to compensating valve (27). The control valve for the coupler tilt controls the oil flow. The oil flow tilts the quick coupler via the tilt cylinder for the quick coupler (29) .
The control valve (6) is connected to compensating cylinders (21). The compensating cylinder extends when the boom is raised. The compensating cylinder retracts when the boom is lowered. The compensating cylinder transfers oil to the tilt cylinder and from the tilt cylinder. The transfer of the oil automatically maintains the selected angle of the quick coupler.
Control valve (7) controls the oil flow to boom extend cylinder (24). Load control valve (23) blocks oil in the head end of the telescoping cylinder on machines that have a boom with two sections. Load control valve (23) blocks oil in the head end and the rod end of the cylinder on machines that have a boom with three sections. This holds the cylinder in position. The load control valve also regulates the cylinder speed when the boom is being retracted.
Control valve (8) controls oil flow to the boom raise cylinder (26). Load control valve (25) blocks oil in the head end of the cylinder. The load control valve also regulates the cylinder speed when the boom is being lowered.
Manifold (31) and relief valve (31) contain a pressure reducing valve which supplies the joystick and solenoid valve group (15) with pilot oil. Manifold (31) and relief valve (31) also contain the signal relief valve which limits the maximum load signal to the pump.
Each control valve is equipped with a highest pressure compensating check valve. To control the oil flow to the cylinders, the check valve works with the resolved signal pressure. If the cylinders were not equipped with the lock valves, the check valves would also act as load check valves.
Solenoid valve group (15) contains the differential lock control valve (13) and solenoid valves (10), (11), and (12). Line (14) from the solenoid valve group supplies oil to the service brake cylinder.
The brake system is described in Service Manual, SENR5844.
Differential lock solenoid valve (13) is controlled by a cab mounted switch. When the solenoid is energized, oil pressure engages the differential lock in the front axle. The lock is disengaged by spring force when the valve is de-energized. Solenoid valves (10), (11), and (12) are controlled by switches on the joystick. When the switches are released the solenoids are de-energized.
Side movement of the joystick operates either the boom extend or the boom retract on machines with the following configurations: type 2, type 4 and type B. The joystick also operates the following configurations: type 1, type 3 and type A. Refer to Systems Operation/Testing and Adjusting, "Boom Hydraulic System" for additional information on the two types of arrangements.
The frame leveling cylinder is a standard item on the TH63 and TH83 machines. The frame leveling cylinder is an optional item on the TH82 machine. The frame leveling cylinder is not available on the TH62 machines. In order to level the machine on uneven ground, the machine frame can be angled to the left or right in relation to the axle by using frame leveling cylinder (1). Control valve (3) is directly operated by solenoids which are controlled by a three-position switch. When the switch is released, load control valve (2) blocks the oil in the head end and the rod ends of the cylinder.