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| Illustration 1 | g00829707 |
Hydraulic System for Auxiliary Services (1) Diverter valve (2) Quick coupler cylinder (7) Work tool cylinder (17) Joystick (45) Implement section of bank valve (auxiliary section) (35) Line (load sensing) (31) Piston pump (5) Bank valve (PP) Pump delivery (CP1) Work tool cylinder (pressure oil) (R) Return oil (S) Suction oil (LS) Load sensing oil (P) Pilot oil | |
The main components of the auxiliary system are implement section (45) of bank valve (5) and diverter valve (1). The diverter valve is equipped with two pairs of quick couplers in order to provide a connection to either work tool cylinder (2) or to work tool cylinder (7).
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| Illustration 2 | g00686184 |
Early Joystick | |
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| Illustration 3 | g00849471 |
Current Joystick | |
Implement section (45) is directly operated by solenoids. The solenoids are controlled by switches on joystick (17) .
Control of implement section (45) is not proportional. When the selector switch on joystick (17) is operated, the spool is fully offset. This connects the service that is selected to piston pump (31) and to hydraulic tank (30). The output of the piston pump is controlled by the load pressure from work tool cylinder (7). Load pressure from the auxiliary cylinder is transmitted to the pump via the resolver network of bank valve (5) and the load sensing line (35).
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| Illustration 4 | g00849539 |
Location of Diverter Valve (1) for the Auxiliary Service | |
A manually operated diverter valve (1) is located at the boom head. The diverter valve permits the operation of one attachment at a time. The diverter valve is equipped with quick couplers for the hydraulic lines of the attachment.
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| Illustration 5 | g00849540 |
Location of rolling hoses | |
The diverter valve is connected to bank valve (5) by rolling hoses which are located inside the boom.
Relief Valve
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| Illustration 6 | g00831904 |
Location of the Relief Valves in the Bank Valve (4) Signal relief valve (43) Single stage relief valve (45) Implement section (auxiliary services) | |
Relief valves (43) control the load pressure in the work ports of auxiliary section (45) on the implement section of the bank valve. The relief valves are set at a lower pressure than signal relief valve (4) in the end section of the bank valve.
Single Stage Relief Valve
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| Illustration 7 | g00746773 |
Single Stage Relief Valve (43) (54) Spring (55) Spring (56) Valve seat (57) Spring (58) Hole (59) Anticavitation piston (60) Service port (61) Piston (pressure relief) (62) Tank return port (63) Orifice (pilot stage) (64) Anticavitation chamber (65) Pilot valve | |
Pressure Relief
Pressure in service port (60) acts on the face of anticavitation piston (59). The same pressure acts on pilot valve (65) and at the rear of piston (61) by way of orifice (63) .
At the set pressure, pilot valve (65) is unseated. The pilot valve moves away from valve seat (56) against the force of spring (54). Pressure in anticavitation chamber (64) is relieved around the outside of anticavitation piston (59) to tank return port (62) .
Pressure that acts on the face of piston (61) unseats the piston and the piston moves away from the seat in anticavitation piston (59) against the force of spring (57). This allows pressure in service port (60) to be relieved through holes (58) in the anticavitation piston.
Makeup Flow
If pressure in service port (60) falls below the pressure in tank return port (62), anticavitation piston (59) is offset by pressure in the tank return port and spring (55) is compressed. Oil enters the service port from the tank return port. When the pressure in the service port is equal to the pressure in the tank return port, anticavitation piston (59) is reseated by spring (55) .