DRESSTA TD-25M EXTRA, Service Manual

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SECTION 10
HYDRAULICS
Page 18
TD-25M EXTRA DRESSTA
TEST AND ADJUSTMENT
8. CYLINDER TIME CYCLE
Blade Tilt
NOTE: Before performing cylinder time cycle, perform PISTON PACKING TEST to insure that
cylinder is satisfactory. If cylinder is satisfactory, but tilt circuit is weak or slow, problem could
be either hydraulic pump or tilt relief valve. Loss of flow can be caused by tilt relief valve not
sealing, allowing oil to flow into reservoir passage.
To check pump, following time cycles should be observed when tilting blade to left and to right.
1. Lift blade off ground and run engine at full throttle. Position the blade 300 [mm] over the ground
with tilt/pitch cylinders piston rods pulled out in their midposition; and next place the blade in its
extreme double tilt left position.
2. Starting with blade in its extreme double tilt left position, put control lever in RIGHT DOUBLE
TILT and read and record time it takes blade to reach its extreme position. Tilt cycle should take
not more then 2.2 seconds. Starting with blade in its extreme double tilt right position, put
control lever in LEFT DOUBLE TILT and read and record time it takes blade to reach its
extreme left position. Double tilt cycle should take not more than 2.4 seconds too. Repeat left to
right and right to left several times and take an average of readings.
3. If average cycle times are more than above mentioned, middle pump should be repaired or
replaced as necessary.
NOTE: In case of fully retracted blade tilt cylinders maximum cylinder time cycle can reach
16.0 seconds.
Blade Lift
NOTE: Before performing cylinder time cycle test, perform cylinder blade tilt test to insure that
middle pump is correct.
NOTE: Before performing cylinder time cycle test, perform blade lift cylinder drift test to insure that
control valve, cylinders and valves are performing satisfactorily.
If there is no excessive drift when blade lift control is in HOLD position, but slow load speed,
slow response or low power is present in RAISE position, problem could be either hydraulic
pump or pressure relief valve. Loss of flow can be caused by pressure relief valve not
sealing, allowing oil to flow into return to reservoir passage. Refer to Paragraph 5, RELIEF
VALVE PRESSURE TEST.
To check pump, following time cycles should be observed when raising blade.
1. Position machine so that blade will not touch ground in its fully lowered position. Run engine
at full throttle.
2. Starting with blade in its fully lowered position, put control lever in RAISE and record time
it takes blade to reach full raised position. Repeat this procedure several times and average
time readings.
3. Lift cycle should take not more than 3.5 seconds. If average cycle time is more than
3.5 seconds, front pump should be repaired or replaced as necessary.
NOTE: This check should be made only in blade raising cycle.