Komatsu PC88MR-10 Shop Manual page 275

Function
This function automatically sets the lock lever in the same state as when it is locked to prevent the work
equipment or the machine continues its operation when the lock lever is unlocked while the work equipment
control lever or the travel lever is operated.
Operation
When an oil pressure switch or a sensor detects pressure higher than specified pressure (D) or an attachment
drive signal is input within certain time (C) after the lock lever is unlocked (A), this function judges that the
operation is abnormal and the pump controller outputs the lock lever automatic lock relay drive signal to shut
off the current to PPC lock solenoid to lock the machine (B).
a When the hydraulic oil temperature is low or high-viscosity hydraulic oil used, the pressure may not
increase within time (C) and the lock lever automatic lock control may not operate.
A: PPC lock lever is canceled
B: Lock lever automatic lock operates
C: Within 0.4 sec
D: 5 kPa
Control when lock lever automatic lock cancel switch is "ON"
If PPC solenoid valve does not operate and the operator cannot work because of abnormality in the controller,
the operator can operate the machine by operating lock lever automatic lock cancel switch (1).
At this time, the lock lever automatic lock control function does not work.
a: Emergency (when abnormal)
b: Normal (when normal)
a Lock lever automatic lock cancel switch (1) is an alternate type switch. If it is set to "EMERGENCY" (a)
position while PPC lock lever is in the free state, the lock lever automatic lock cancel pilot lamp lights up
on the display.
PC88MR-10
10 Structure and function
Electrical control system
10-197