22 - 1
Torque Converter Stall Test
Note: Before completing the torque converter stall test,
make sure that the mainline and clutch pressures are
correct. If the pressures are incorrect, the clutches could
slip, causing premature wear of the clutch friction plates.
Also, make sure that the machine neutral circuit pressure
(including steer circuit) is correct (14 bar; 200 lbf/in
2
maximum).
1 Ensure that the engine and transmission are at normal
working temperature. Run engine at maximum speed
and check the No Load Speed (High Idle Speed -
U.S.A). See Engine Technical Data for correct figure;
adjust if necessary.
2 Apply parking brake A and footbrake firmly B, select
4th Speed Forward and open throttle C fully. Engine
speed should be as specified at Torque Converter
Stall in Transmission Technical Data. Select Reverse
and repeat test.
Note: When fully engaged, the parking brake electrically
disconnects the transmission drive; this prevents the
machine from being driven with the parkbrake on. Therefore,
so that we can complete the test, move the parkbrake lever
fractionally forward until the warning light is just
extinguished; hold the lever in this position for the duration
of the test. DO NOT move the lever too far forward,
otherwise the parkbrake will not be fully operational.
Alternatively, disconnect the switch at the park brake.
DO NOT stall the converter for longer than 30 seconds or
the transmission fluid will overheat.
3 If engine speeds are higher than the stated figures
check the transmission for clutch slippage or internal
leakage.
If engine speeds are below the stated figures either the
engine is losing power and should be
serviced/overhauled or the torque converter reaction
member clutch is slipping.
To check the engine, make sure the main relief valve is
set correctly, select Neutral, open throttle fully and
operate an excavator service to 'blow off' the main
relief valve. Engine speed should fall to slightly above
the Maximum Governed Speed (see Engine
Technical Data). If engine speed is correct the torque
converter is faulty.
Note 1: The engine can also be checked by doing a stall test
and 'blowing off' the main relief valve simultaneously. The
speed should be as stated in Technical Data, Torque
Converters (Converter + MRV)
Note 2: Maximum Governed Speed is a datum figure only.
It cannot be adjusted or checked with the engine installed in
the machine.
Section F Transmission
9803/7130
Section F
22 - 1
Issue 1
Service Procedures
391811
AA
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CC
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