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| Illustration 1 | g00796352 |
Location of Components on Bank Valve (1) Valve for quick coupler (pins) (2) Gallery (return) (3) Passage (4) Adjusting screw (boom lower) (5) Passage (load sensing) (6) Adjusting screw (boom retract) (7) Line to dual relief valve (8) Relief valve for quick coupler (tilt) (9) Dual relief valve (10) Relief valve for auxiliary services (11) Signal relief valve (12) Port (return from stabilizer control valve) (13) Passage (return) (14) Regulator valve (15) Port (load sensing from stabilizer control valve) (16) Port (supply to stabilizer control valve) (17) Gallery (supply) (18) Orifice (19) Load check valve (20) Resolver valve (21) Flow control valve (22) Port (steering supply) (23) Port (inlet) (24) Pressure reducing valve (25) Port (load sensing to pump) (26) Port (return to hydraulic tank) (27) Port (load sensing from steering) (28) Port for quick coupler (pins) (29) Inlet section (30) Implement section for boom raise/lower (31) Implement section for boom extend/retract (32) Implement section for quick coupler (tilt) (33) Implement section for auxiliary services (34) Implement section for frame leveling (35) End section | |
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| Illustration 2 | g00760218 |
Location of Bank Valve | |
The bank valve is located on the right side of the machine in the engine enclosure.
The pump delivery line is connected to port (23) of inlet section (29). The inlet section is equipped with pressure reducing valve (24), flow control valve (21) and valve (1) for the quick coupler.
Pressure reducing valve (24) supplies the pilot control system by way of the joystick control. The pressure reducing valve also supplies the service brake boost pressure. The pressure reducing valve is preset at 2650 ± 150 kPa (385 ± 20 psi). This is not adjustable.
Flow control valve (21) provides priority flow to the steering from port (22). When the flow requirements of the steering system have been met, supply oil flows through gallery (17) which passes through implement sections (30), (31), (32), (33), and (34) to end section (35). Port (27) is connected to a load sensing line from the steering system in order to provide a pilot signal to the flow control valve.
The main return of oil to the hydraulic tank is through gallery (2) that is connected from the end section of the bank valve through the implement sections to port (26) .
Valve (1) increases the auxiliary system pressure in order to disengage the pins for the quick coupler. Port (28) for the valve is externally connected to dual relief valve (9) through line (7). The valve is operated by a solenoid which is controlled by a switch on the instrument panel. The dual relief valve, which operates at a lower pressure for the auxiliary services, operates at a higher pressure when the solenoid is energized. The stem of the valve is held by spring force in order to close the port when the solenoid is de-energized.
All the implement sections are equipped with a directional spool that is spring centered. When the controls are in the HOLD position, the directional spool is in the NEUTRAL position and the directional spool is closed at the work ports. Oil can not return to the hydraulic tank and the work ports are not connected together.
The following implement sections are equipped with a directional spool that is proportionally controlled by pilot oil pressure.
- Implement section (30) for boom raise/lower
- Implement section (31) for boom extend/retract
- Implement section (32) for the quick coupler (tilt)
Implement section (33) for the auxiliary services and implement section (34) for the frame leveling are equipped with a directional spool that is not proportionally controlled. The directional spool has three positions and the directional spool is operated by solenoids. When the controls for the implement sections are operated, the solenoid is energized and the directional spool is fully offset.
All the implement sections contain a pressure compensating check valve. The pressure compensating check valve consists of load check valve (19) and resolver valve (20). Load pressure is transmitted to the pressure compensating check valve through orifice (18). Only the components for implement section (30) are called out in Illustration 1. When the load check valve opens during operation, the load check valve connects with the resolver valve. The load check valve and the resolver valve act together.
The pressure compensating check valves allow oil flow to be proportionally divided between each of the operating circuits when the flow demands of the system exceed the total flow that is available from the pump. The check valves also maintain constant cylinder speed which is proportional to the position of the joystick control. The cylinder speed is independent of engine speed.
The resolver valves are connected to each other through passages (3) and (5). The joining of resolver valves is designed to allow the highest working pressure to be felt at the pressure and flow compensator valve on the pump which is connected through a line from port (25). For example, if more than one implement is being operated, the implement with the highest pressure will counteract the implements that are operating at lower pressures. The pressure and flow compensator valve matches the pump output to the highest working pressure.
Signal relief valve (11) is located in end section (35). Pressure in the load sensing system acts against a poppet which is normally held against a seat by spring force. If the pressure reaches the relief setting, the poppet lifts off the seat and oil flows through passage (13) to gallery (2) in order to return to the hydraulic tank. For information on the adjustment procedure for the signal relief valve, refer to Systems Operation, Testing and Adjusting, RENR3475, "Steering Signal Pressures - Test and Adjust".
Regulator valve (14) is located in the signal relief valve. Oil continually flows through the regulator valve from the load sensing system into passage (13) and gallery (2) in order to return to the hydraulic tank. When a load is taken off a service, the regulator valve will bleed down any trapped pressure in the load sensing system.
The end section is connected to the stabilizer control valve through the following ports:
- Port (16) connects the pump supply from the bank valve to the stabilizer control valve.
- Port (15) connects the load sensing system of the bank valve to the stabilizer control valve.
- Port (12) is the tank return port from the stabilizer control valve to the bank valve.
Relief valves (8) are installed in implement section (32) for the quick coupler (tilt). Refer to Systems Operation, "Compensating System" for further information on the operation of the relief valves.
Relief valves (9) and (10) are operated by load pressure at the auxiliary work ports on implement section (33). The relief valves are set at a lower pressure than the implement relief valve in the end section. Refer to Systems Operation, "Auxiliary System" for further information on the operation of the relief valves.
Adjustment screw (4) and adjustment screw (6) are used during part of a procedure for boom lowering and retracting without hydraulic power. Refer to Operation and Maintenance Manual, SEBU7371, "Boom Retracting and Boom Lowering without Hydraulic Power" for a further description of the procedure.