SECTION 10 HYDRAULICS
Page 14
TD-25M EXTRA DRESSTA
TEST AND ADJUSTMENT
4. Pressure obtained in Steps 1 or 2 and 3 should range over 16900 to 17600 [kPa], if not proceed
as follows:
If both low and high idle pressure readings are alike but not as specified, system is
operating correctly but relief valve must be adjusted. Proceed to Step 5. If relief
pressure is 16900 - 17600 [kPa] at high idle but cannot be reached at low idle, refer to
Paragraph 10, PRESSURE DIAGNOSTIC CHART in this SECTION.
5. Remove acorn nut (1, Fig. 10.9) and outer washer (14) and loosen jam nut (2). Turn adjusting
screw (3) clockwise to increase pressure or counterclockwise to decrease pressure. After
correct pressure is obtained, lock jam nut (2) and install outer washer (14) and acorn nut (1).
Recheck oil pressure.
6. ONE SPOOL CONTROL VALVE; Remove plug from raise supply port and reconnect supply
hose to valve port.
7. Remove test gauge from the quick disconnect fitting and close the door from right side.
Pilot Pressure Relief Valve Pressure Test
1. Open the door from right side and connect an 4 [MPa] gauge with quick coupler (see SERVICE
/SPECIAL TOOLS in this Section) to the quick disconnect fitting (5, Fig. 10.7) and proceed as
follows.
2. Once operating temperature is reached, run engine at full throttle and read and record pressure
on gauge at which relief valve unloads.
3. Repeat Step 2 with engine at low idle.
4. Pressure obtained in Steps 2 and 3 should be 2400 – 2560 [kPa], if not proceed as follows:
If both low and high idle pressure readings are similar but not as specified, system is
operating correctly but pilot pressure valve must be repaired. Proceed to SECTION
10B, VALVES. If relief valve pressure is within 2400 – 2560 [kPa] at high idle but
cannot be reached at low idle, refer to SECTION 10A, PUMPS.
5. Remove test gauge from the quick disconnect fitting and close the door from right side.
6. BLADE LIFT CYLINDERS DRIFT TEST (MACHINE WITHOUT RIPPER)
The problem of cylinders drift can be traced to two main causes, which are internal and external
leakage. External leakage is not detailed here, since it can be visually. Internal leakage is not
always readily pinpointed to its source and may require a series of tests to isolate the problem.
There are six places that might be a source of leakage; one of hydraulic cylinders might be leaking
past piston packing or piston poppet(s), control valve could leak at spool and/or quick drop valve
spool could be stuck, shuttle valve(s) could leak, pilot pressure valve could leak or blade pilot
control valve could leak.
Following is a series of tests to trace the source of internal leakage.
1. Raise and lower blade through its full travel to wash out any foreign material which might prevent
piston by pass poppets from seating. Oil temperature should be 82 - 88 [°C].
2. Lower the ripper to the ground.
3. Fully raise blade and move lever to LOWER position releasing it to HOLD before blade drops
to ground.
4. Perform blade lift cylinders drift test. Check cylinders for drift, rods should travel out of cylinders
no more than 18 [mm] per minute.
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