COMPONENT OPERTATION / Signal Control Valve ARM FLOW RATE CONTROL VALVE CON- TROL SPOOL, FLOW COMBINER VALVE CONTROL SPOOL, SWING PARKING BRAKE RELEASE SPOOL Arm Flow Rate Control Valve Control Spool: To Hydraulic Oil Tank Boom Raise Control Pilot Pressure NOTE: The spools above are identical in opera- tional principle. 1. The arm flow rate control valve control spool is shifted by arm roll-in pilot pressure and supplies boom raise pilot pressure to the arm flow rate control valve in control valve. 2. The flow combiner valve control spool is shifted by right travel pilot pressure and supplies primary pilot pressure to the flow combiner valve in con- trol valve. 3.
The swing parking brake release spool is shifted by the boom, arm, bucket, swing or auxiliary pilot pressure and supplies primary pilot pressure to the swing motor. T178-03-06-014 Flow Combiner Valve Control Spool: Arm Roll-In Pilot Pressure To Arm Flow Rate Control Valve To Hydraulic Oil Tank Primary Pilot Pressure T178-03-06-014 Swing Parking Brake Release Spool: Right Travel Pilot Pres- sure To Flow Combiner Valve To Hydraulic Oil Tank Primary Pilot Pressure T178-03-06-014 Boom, Arm, Bucket or Aux- iliary Pilot Pressure To Swing Motor T3-6-14 ool Spring T17 ool Spring T17 ool Spring T17