SECTION 10 HYDRAULICS
Page 20
TD-25M EXTRA DRESSTA
TEST AND ADJUSTMENT
10. PRESSURE DIAGNOSTIC CHART
PROBLEM PROBABLE CAUSE
Low pressure at low idle only for one
cylinder pair, blade or ripper
One of cylinders leaking. Refer to Paragraph 6,
BLADE LIFT CYLINDERS DRIFT TEST
or , Paragraph 9, PISTON PACKING TEST.
Low pressure at low idle for both blade lift
and ripper cylinders
Worn front pump. Refer to SECTION 10A,
PUMPS.
Low pressure at low and high idle for
both blade lift and ripper cylinders
Main relief valve not sealing. Dismantle relief
valve for inspection and repair.
Refer to SECTION 10B, VALVES.
Low pressure at low idle only for one
movement tilt or double tilt (if equipped)
One of cylinders leaking. Refer to Paragraph 9,
PISTON PACKING TEST.
Low pressure at low idle for both movement
tilt and double tilt
Worn middle pump. Refer to SECTION 10A,
PUMPS.
Low pressure at low and high idle for both
movement tilt and double tilt
Tilt relief valve not sealing. Dismantle relief
valve for inspection and repair.
Low pressure at low idle for pilot valves Worn rear pilot pump. Refer to SECTION 10A,
PUMPS.
Low pressure at low and high idle for
pilot valves
Pilot pressure valve problem. Dismantle valve
for inspection and repair. Refer to SECTION 10B,
VALVES.
11. FAN DRIVE SYSTEM PERFORMANCE TEST
WARNING! Be sure the area in front and behind the machine is clear of personnel
and obstructions. DO NOT allow anyone near the trucks or on the access steps
during this test.
NOTE: Performing test will require two people, one person to operate the machine, the second
person to time the machine’s performance.
1. Start the cold engine. Use a Digital Optical Tachometer (see SERVICE /SPECIAL TOOLS) to
record fan minimum speed. Do it with the engine coolant, engine charge air and drive train
system oil temperatures below minimum values given in SPECIFICATIONS in this Section.
2. Apply torque converter stall speed procedure (refer to SECTION 7, DRIVE TRAIN) to warm up
the drive train oil until the fan speed starts to rise from its minimum speed; record this oil
temperature. Further warm up the oil until fan has smoothly reached its maximum speed at
required oil temperature. Record fan maximum speed at the maximum speed oil temperature.
With oil temperature still raising the fan speed should stay at maximum speed level. Refer to
SPECIFICATIONS in this Section.
3. If any recorded fan velocities is out of specifications or the fan fails to operate steplessly
between minimum and maximum speed range, refer to “Fan drive system diagnosis” in
Paragraph 4, SERVICE DIAGNOSIS in this Section.
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