Komatsu D31EX-21, Operation & Maintenance Manual, Page: 179 / 256

OPERATION
TROUBLESHOOTING
3-127
CHASSIS 3
q
( ): Always contact your Komatsu distributor when dealing with these items.
q
In cases of abnormalities or causes which are not listed below, contact your Komatsu distributor for repairs.
Problem Main causes Remedy
When brake pedal is depressed,
machine does not stop
•Defective adjustment of brake limit
switch
•Defective brake valve solenoid (•Adjust, check, repair)
(•Check, repair)
Track comes off •Track too loose
•Adjust track tension, see WHEN
REQUIRED
Abnormal wear of sprocket •Track too loose or too tight
Blade, rise slowly, does not rise
•Lack of hydraulic oil
•Safety lock lever in LOCK position
•Wear, scuffing of charge pump
•Defective work equipment PPC
valve
•Defective main control valve
•Add oil to specified level, see
CHECK BEFORE STARTING
•Set lever in free position
(•Check, repair)
(•Check, repair)
(•Check, repair)
Does not steer even when steering
is operated
•Parking lever in LOCK position
•Wear, scuffing of charge pump
•Defective EPC valve of HST pump
•Defective travel lever •Set lever in free position
(•Check, repair)
(•Check, repair)
(•Check, repair)
Noise is genereted from idler •Lack of oil in idler
•Add oil to specified level, see
WHEN REQUIRED
Lacks drawbar pull (cannot travel
at full speed)
•Lack of drive power from engine
•Defective HST pump, motor
•Defective relief valve •See ENGINE
(•Check, repair)
(•Adjust, check, replace)
Travel speed does not rise quickly
•Low temperature of HST oil
•Lack of drive power from engine •Warm up machine
•See ENGINE
Machine does not move off when
steering, directional and gear shift
lever is placed in gear
•Parking lever in LOCK position
•Wear, scuffing of charge pump
•Brake valve lever in LOCK position
•Does not work brake release sole-
noid
•Defective EPC valve of HST pump
•Defective travel lever
•Set lever in free position
(•Check, replace)
•Set lever in free position
(•Check, repair, replace)
(•Check, replace)
(•Check, replace)
Only one track operates •Defective HST pump (•Check, replace)
Machine steers when steering is
not operated
•Defective travel lever
•Defective HST pump, motor
•Defective motor rotation sensor
•Low temperature of HST oil
•Air in HST oil system (•Adjust, check, repair)
(•Adjust, check, repair, replace)
(•Adjust, check, replace)
•Warm up machine
(•Bleeding air)
HST oil temperature overheats
(indicator enters red range)
•Excessive load when operating
•Clogged oil cooler fin or damaged
fin
•Shift down one position, or reduce
the load and increase the speed
when operating
•Clean or repair, see EVERY 500
HOURS SERVICE