11. EXPLANATION OF COMPONENTS 13. TWO STAGE PRESSURE RELIEF This switch is used to switch the safety valve set pressure at the head end of the boom cylinder to two levels. a Low pressure setting: The boom thrust force is weak, so the swaying of the chassis is small during digging operations, and digging opera- tions can be carried out smoothly. This is used for general digging operations on normal ground, soft rock, or blasted rock. b High pressure setting: The thrusting force of the boom be- comes more powerful, so it is easy to twist and swing or escape from soft ground. It is effective in carrying out dig- ging operations using the bucket and the weight of the machine in confined areas.
14. CAB LAMP SWITCH This lights up the cab lamp. ON position: Lights up The cab lamp can be turned on even when the starting switch is at the OFF position, so be careful not to leave it on by mistake. 15. PUMP CONTROL OVERRIDE SWITCH When normal: Switch is down When abnormal: When the monitor display shows E02 (TVC valve system error), it is possible to carry out operation when this switch is moved up. The pump control override switch is designed to allow opera- tions to be carried out for a short period when there is an abnormality in the pump control system (TVC valve system error). The abnormality must be repaired immediately. 16. SWING LOCK OVERRIDE SWITCH When normal:
Switch is down When abnormal: When the monitor display shows E03 (swing brake system error), the brake is cancelled and it becomes possible to swing the upper structure when this switch is moved up, so normal operations can be carried out. However, the swing brake remains cancelled. The swing lock override switch is designed to allow operations to be carried out for a short period when there is an abnormality in the swing brake electrical system (swing brake system error). The abnormality must be repaired immediately. PC450-ENG 2-18