Bad Boy 1022H - HST System Troubleshooting

B22W-202010
4
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CHAPTER 4 HST SYSTEM 1022H TRACTOR
4. TROUBLESHOOTING
In case that HST shows troubles, it is as a general rule to replace the Assy. For a more clear-cut explanation
and understanding, here is a detailed outline of troubles, causes, checking points, and actions.
TROUBLE CAUSE CHECK LIST ACTION
1. Even when
turning an
operating lever,
Output Shaft
does not rotate.
1. A set value of Low Pressure
Relief Valve drops.
Measure the pressure of
Charge Circuit and check that
it reaches its set value.
Replace with a new component
if failing to go up to a specied
pressure.
2. A set value of High Pressure
Relief Valve drops.
Measure the pressure of High
Pressure Circuit and check
that it reaches its specied
value.
Replace with a new component
if failing to go up to its specied
pressure.
3. The Seat of Check Valve
(HST) is defective.
(Low/high pressure state of
HST is out of normality)
Measure the pressure of
Charge Circuit and Low
Pressure Circuit, and check
that it reaches its specied
value.
Replace with a new component
if failing to go up to its specied
pressure.
4. Gear Pump gets damaged.
Flow rate drops.
Measure the pressure of
Charge Circuit and check
that it reaches its specied
pressure.
Replace with a new component
if failing to go up to its specied
pressure.
5. Air comes into HST.
- Let the air out of HST.
- Check the ow rate of tank.
- Check if pipe is out of order
(ex: suction of air caused
by defective seal).
- Replenish a hydraulic oil
(operating oil).
- Repair the pipe.
6. Main parts of HST
malfunction because of
being damaged.
Input/output shaft or
coupling shows problem.
- Check that output rotation
number of HST goes up to
its specied value.
- Check if Spline of Coupling
is worn out.
- Replace with a new
Coupling.
- Clean the Hydraulic Circuit
in Main Body and replace
with a new HST ASSY.
2. Even when
placing a Pedal
in its neutral
position,
rotation does
not stop.
1. Check Valve malfunctions.
(ex: Hole is clogged)
- Measure the pressure of
High Pressure Circuit.
- Check the conversion state
of high and low pressure
when moving it backward/
forward.
After going through
disassembly and washing
process, reassemble it.
2. A Moving Swash Plate is
worn out.
Adjust the Pedal slightly from
its neutral position and check
that there is any point where its
output rotation stops.
Replace with a new component
if there is no point where its
output rotation stops.
3. An operating torque of Lever
increases.
The force of Return Spring,
at the end of Main Body
Link, deteriorates, which
makes the return force of
Pedal poor.
- Measure an operating
torque at the end of
Trunnion Shaft.
- Check the force of Return
Spring.
Replace with a new Swash
Plate Bush.
Replace with a new Link Part.