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| Illustration 1 | g00886584 |
Solenoid valve for the swing signal | |
When the left hand pilot valve is activated for a swing function, pilot oil is sent to one end of the swing control valve in order to actuate the swing function. Pilot oil flows through the resolver valve that is located in the swing control valve. The swing pilot pressure opens the pressure switch for the swing parking brake and the pilot oil flow upstrokes the swing piston pump. The pressure switch for the swing parking brake signals the Machine Control Module (MCM) that swing has been requested.
As the swing motor begins to accelerate, the sensor for the swing speed senses the acceleration of the swing motor. The sensor sends a signal to the MCM. After the swing motor accelerates for 1/4 of a second, the MCM energizes the solenoid valve for the swing signal. Opening the solenoid valve allows the pilot oil flow to increase the pressure setting of the swing dual pressure relief valve.
When the swing motor stops accelerating or the swing motor exceeds 627 rpm the MCM de-energises and closes the swing signal solenoid valve and the flow of pilot oil is cut-off. When the pilot oil to the dual pressure relief valve is stopped, the dual pressure relief valve returns to the low pressure setting. The MCM will not reset the dual pressure relief valve to the high pressure setting until the swing speed sensor signals the MCM that the swing motor is below 627 rpm and again accelerating or the swing motor has stopped turning and again accelerating.
When the left hand pilot valve is returned to NEUTRAL the swing pilot pressure to the swing pressure switch is blocked. The loss of the swing pilot pressure closes the swing pressure switch. Without a pressure signal from the swing pressure switch the MCM de-energises and closes the solenoid valve for the swing signal and the flow of pilot oil is cut-off. When the pilot oil to the dual pressure relief valve is stopped, the dual pressure relief valve returns to the low pressure setting. The MCM will not reset the dual pressure relief valve to the high pressure setting until the swing speed sensor signals the MCM that the speed of the swing motor is below 627 rpm and again accelerating or the swing motor has stopped turning and again accelerating.