Doosan D20G, Service Manual

Page: 828 / 1209

Power Train Testing And Adjusting 22
Testing and Adjusting
Troubleshooting
Troubleshooting can be difficult. A list of possible
problems and corrections is on the pages that follow.
This list of problems and corrections will only give an
indication of where a problem can be and what
repairs are needed. Normally, more or other repair
work is needed beyond the recommendations on the
list. Remember that a problem is not necessarily
caused only by one part, but by the relation of one
part with other parts. This list can not give all
possible problems and corrections. The serviceman
must find the problem and its source, then make the
necessary repairs.
Always make visual checks first. Check the
operation of the machine and then check with
instruments.
WARNING
When testing and adjusting the power train,
move the machine to an area clear of
obstructions, and with safe ventilation for the
exhaust. When drive wheels are off the ground
for testing, keep away from wheels that are in
rotation.
Visual Checks
1. Check the oil level in the transmission with the
engine running and with the transmission in
NEUTRAL.
2. Check all oil lines, hoses and connections for
leaks and damage. Look for oil on the ground
under the machine.
3. Move the lever for the direction control to
REVERSE and FORWARD positions. The detents
must be felt in each position.
4. Check the oil in the transmission for loose
particles.
a. Bronze-colored particles give an indication of a
clutch failure.
b. Shiny steel particles in the filter give an
indication of a pump failure.
c. Rubber particles give an indication of a seal
failure or hose failure.
If you find metal or rubber particles, all components
of the hydraulic and lubrication systems must be
washed clean. Do not use parts with damage. Use
new parts.
Checks During Operation
NOTICE
Before these checks are started, fill the transmission
with oil to the correct level.
Power Shift Transmission
With the engine running and brakes on, move the
selector lever to all positions. The detents must be
felt in each position.
Operate the machine in each direction. Make note of
all noises that are not normal and find their sources.
If the operation is not correct, make reference to the
CHECK LIST DURING OPERATION for “problems”
and “probable causes”.
Check List During Operation
Problem: Transmission does not operate in
either direction or does not engage (slips) in all
directions.
Probable Cause :
1. Low oil pressure caused by :
a. Low oil level.
b. Inching control valve linkage loose, broken or
adjustment not correct.
c. Failure of the oil pump.
d. Leakage inside the transmission.
e. Pressure regulator valve stuck.
2. Mechanical failure in transmission.
3. Failure of the bevel pinion or the ring gear.
Problem: Transmission does not shift.
Probable Cause:
1. Low oil pressure.
2. Pressure regulator valve will not move (stuck).
3. Control linkage worn, broken or adjustment is not
correct.