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| Illustration 1 | g00509483 |
(1) "+" quick coupler port for extended cylinder (2) "-" quick coupler port for retracted cylinder (3) Load check valves | |
Each implement control valve has a pair of quick couplers. The quick couplers will accept SAE standard connectors or ISO standard connectors.
Note: Male couplers are available from any Caterpillar dealer. A 9X-2017 Coupler is available for 3/4 inch hose. A 9X-2018 Coupler is available for 1/2 inch hose.
The quick couplers can be connected under pressure and disconnected under pressure. The quick couplers are self-sealing. The quick couplers are mounted at the rear of the machine and attached to the implement valve bank.
Couplers (1) that are located on the left side of the implement control valve are pressurized when the implement control lever is in the EXTEND position. Couplers (2) that are located on the right side of the implement control valve are pressurized when the implement control lever is in the RETRACT position. Dust caps limit the amount of dirt that enters the couplers.
Oil flow to each quick coupler is governed by the corresponding implement control lever. The implement control levers are located in the right hand console of the cab. Each implement control lever is coded with a colored stripe in order to match the color coded decal by the implement control valve bank at the rear of the machine. The oil flow direction is molded into each dust cap on the coupler for easy identification.
The quick couplers are prepared for an implement breakaway. When an implement becomes disconnected from the machine, the implement hoses are pulled from the implement control valve. The quick couplers are designed to prevent the loss of oil. If the male hose coupling is pulled out of the quick coupler, oil cannot flow even while the implement control valve is actuated. The quick couplers are threaded into cast aluminum blocks that are bolted to the implement control valves.
The #1 implement control valve and the #2 implement control valve contain load check valves (3) in the EXTEND position. The load check valves are operated by pilot pressure. The load check valves are installed in order to limit drift of the implement while the implement control lever is in the HOLD position. Hydraulic pressure is used in order to open the load check valves. Therefore, the engine must be running in order to release pressure from components that are attached to the #1 implement control valve or to the #2 implement control valve.