COMPONENT OPERATION / Others (Upperstructure) Pilot Shut-Off Lever: LOCK Position 1. When the pilot shut-off lever is in the LOCK posi- tion, the pilot shut-off relay is turned OFF and the pilot shut-off solenoid valve is turned OFF. (Refer to Electrical System group / SYSTEM.) 2. Pressure oil from the pilot pump flows to the sig- nal control valve through the spool in pilot shut-off solenoid valve. 3. Oil from the pilot valve flows to the hydraulic oil tank. 4. Therefore, although the control lever is operated, the pilot valve is not operated. Pilot Shut-Off Lever: LOCK Position Pilot Shut-Off Solenoid Valve To Hydrau- lic Oil Tank From Pilot Pump To Pilot Valve Pilot Shut-Off Lever:
UNLOCK Position 1. When the pilot shut-off lever is in the UNLOCK position, the pilot shut-off relay is turned ON and the pilot shut-off solenoid valve is activated. (Re- fer to Electrical System group / SYSTEM.) 2. Therefore, the Circuit to signal control valve and hydraulic oil tank are blocked by the spool in pilot shut-off valve. 3. Pressure oil from the pilot pump flows to the pilot valve. 4. Consequently, when the control lever is operated, the pilot valve is operated. Spool To Signal Control Valve T1J1-03-07-011 Pilot Shut-Off Lever: UNLOCK Position Pilot Shut-Off Solenoid Valve To Hydrau- lic Oil Tank From Pilot Pump To Pilot Valve Spool T1J1-03-07-001 To Signal Control Valve T3-7-2