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WARNING:
vehicle without following all safety precautions
as outlined in the "Safety Practices" section of
this manual. Failure to follow the safety prac-
tices may result in death or serious injury.
7.2
TRANSMISSION DESCRIPTION
Instructions in this section pertain mainly to general spec-
ifications, towing, maintenance information, and trans-
mission removal and installation procedures. Internal
transmission service instructions and detailed specifica-
tions are provided in the ZF 4 WG-98 TS Transmission
Repair Manual (ZF part number 5871 139 002,
JLG part number 8990418).
The ZF 4 WG-98 TS Transmission used in this vehicle is
a four-speed configuration. The "intermediate drop" des-
ignation refers to the relative top-to-bottom length of the
transmission case, chosen for its compatibility with vehi-
cle chassis and operating requirements. Intermediate
drop does not refer to an operational rpm shift or drop.
7.3
TRANSMISSION OPERATION
The transmission is mounted to the engine by a bellhous-
ing. Power from the engine is transmitted the to the trans-
mission by means of a torque converter, bolted to the
engine flywheel and diaphragms. The transmission in
turn transmits power to the transfer case and drive shafts,
driving the front and rear axles.
The torque converter consists of three main components,
the impeller (driver), stator and turbine (driven) in an oil-
filled, enclosed housing. As the torque converter is driven
by the engine flywheel, the impeller (pump) wheel ro-
tates, forcing oil through the stator, which is held station-
ary by the stator shaft bolted to the transmission housing.
This directs the moving oil onto the vanes of the turbine
(driven) wheel, causing the turbine wheel to rotate. The
turbine wheel is connected to the transmission input
shaft, and transfers power to the transmission. Oil from
the turbine wheel is then returned to the impeller wheel to
repeat the process. This process results in an increase in
the torque available at the transmission input shaft.
The transmission and torque converter are powered by
their own internal hydraulic ("transmission fluid") system,
separate from the vehicle hydraulic system. Pressurized
oil for the valve control circuits and torque converter is
supplied by a pump located at the rear of the transmis-
sion. The pump is driven by the central shaft, which in
turn is connected to the impeller of the torque converter.
The transmission is equipped with an external oil cooler,
mounted in the engine heat exchanger (radiator).
Model MMV Rev. 12/04
DO NOT service the
Transmission: ZF 4 WG-98 TS
The transmission gear (or "speed") select lever, an elec-
tric shift control, is located on the left side of the steering
column in the operator's cab. Movement of the gear se-
lect lever energizes the selected transmission shift sole-
noid valves, which, in turn, direct the transmission fluid
under pressure to the selected forward or reverse valve,
and to the designated range (gear or "speed") clutch.
Several factors, including terrain, loading, engine rpm,
axle/wheel-end gearing and the selected transmission
gear determine actual vehicle speed.
To engage the clutch, the gear select lever is placed in
the desired direction (forward or reverse) and range (gear
or "speed") position. Gear select lever movement ener-
gizes the selected direction and range (gear) solenoids,
allowing transmission fluid under pressure to flow through
tubes and passages to the selected clutch shafts. Oil
sealing rings are located on the clutch shaft; these rings
direct oil under pressure through a drilled passageway in
the shaft to a desired clutch. Hydraulic pressure forces
the piston and discs against the back-up plate. Discs,
with edge tangs, clamp against toothed discs on the inner
diameter, enabling the hub and the clutch shaft to lock to-
gether and drive as a unit, providing output power.
7.4
TRANSMISSION SERIAL NUMBER
The transmission serial number plate (1) is located on the
pump side (rear) of the transmission at the bottom right,
toward the vehicle frame. Information specified on the se-
rial number plate includes the transmission model num-
ber, the transmission serial number and other data.
Information on the serial number plate is required in cor-
respondence regarding the transmission.
1
MT0560
7.3
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