Stall Test - Case 580SR Service Manual

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2.6

STALL TEST

The purpose of this test is to determine if the torque
converter and hydraulic clutch assemblies are oper-
ating satisfactorily.
For the test to be conclusive, the transmission hy-
draulic pump and pressure regulating valve must be
operating correctly.
They can be checked by performing the "Line Pres-
sure Test".
The engine and brakes must also be in good work-
ing order.
Z Check the coolant level in the radiator and the oil
level in the transmission. If low, add fluid as re-
quired to bring to the proper level.
Z With the gearshift lever and the shuttle lever in neu-
tral, start the engine and run at 800-1000 rpm until
the transmission temperature reaches 29 °C - 35 °C.
Z Lock the brakes and shift into fourth gear, increase
engine speed to approximately 900 rpm, then shift
the power reversing lever to the forward position.
This will position the control valve so as to direct
high pressure oil to the front clutch.
Z Ensure the brakes are firmly locked so the unit will
not move, gradually depress the foot accelerator
and note the maximum engine speed obtained.
Move the power reversing lever to the neutral po-
sition. The stall speed should be:
Engine 97 HP............................... 1750 ÷ 1850 rpm
Engine 110 HP............................. 1990 ÷ 2140 rpm
IMPORTANT: to prevent the transmission from
overheating, do not allow the engine to operate at
wide open throttle for more than fifteen seconds.
Z Allow the transmission oil to cool to 29 °C - 35 °C.
Check the rear hydraulic clutch by repeating previ-
ous steps, but with the power reversing lever in the
rearward position. Again, cool the transmission oil
by allowing the engine to run at approximately 1000
rpm for one minute.
Z The engine speed noted previously (stall speed)
for both the front and rear clutch assemblies
should be within 150 rpm of each other. If the stall
speed is not within these limits, refer to the diagno-
sis guide for possible causes.
Z With the gearshift lever and power reversing lever
in neutral, set the engine speed at 600-800 rpm,
then shift into any gear ratio. If the gears clash, ei-
ther the front or rear hydraulic clutch assembly is
transmitting power, even though the power revers-
ing lever is in neutral.
SECTION 17 - TORQUE CONVERTERS
NOTE: if the unit creeps forward and the gears
clash, the front clutch is at fault. The rear clutch is at
fault if the unit creeps backward. If the unit does not
creep and the gears still clash, use the stabilizers to
raise the rear wheels off the ground, move the pow-
er reversing lever to neutral and shift into first gear.
Check the rear wheels for rotational direction; if the
wheel rotate rearward, then the rear clutch is at
fault.
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