Return to Master Table of Contents BOOM/FRONT PRIORITY VALVE CONTROL VALVE PRESSURE AND CURRENT ADJUSTMENTS WARNING! This procedure should be done with two people. To reduce the chance of accident or unintended start-up, one person should remain at the operator’s control stand while checks and adjustments are made. The front priority control valves are located inside the compartment behind the cabin. The same jumper harness used for testing the power mode (EPOS) control valve is used to test these two valves. Turn off the engine, disconnect either of the electrical leads and connect the test equipment to that side of the valve.
An in-line "t-style" gauge adapter can be used to connect a 60 bar/870 psi (1,000 psi) test gauge to the outlet (pressure) side of the valve. Set the engine control speed dial to maximum and warm up the engine to at least 45°C (113°F) before making any tests. NOTE: Vent air from the hydraulic system before installing test equipment. Use the lever on the reservoir, while the engine is running. Pour clean replacement fluid back into the system if excessive fluid was lost. Operate the swing and boom simultaneously. Measure signal current and hydraulic pressure through the valve and record the highest and lowest values.
Reset the work mode control to "digging" mode, and then to "trenching" mode and repeat the same tests. NOTE: If recorded values do not conform to the specified current or pressure in the table, readjust as required. Page 14 Hydraulic System Troubleshooting, Testing and Adjustment VALVE FUNCTION DIGGING MODE HAOB730L TRENCHING MODE HAOB740L VOLTAGE PRESSURE VOLTAGE PRESSURE Front Priority 0 V 40 bar (580 psi) 20 - 30 V 0 bar (0 psi)