Lull 944E-42 Service Manual - Manual (Page 179)

6.3 Model 644E-42/944E-42 Rev. 6/04
Transmission: ZF 4WG-92/98 TSC & Transfer Case: ZF TB92-I4
6.2 TRANSMISSION DESCRIPTION
Instructions in this section pertain mainly to general
specifications, towing, maintenance information, and
transmission removal and installation procedures.
Internal transmission service instructions and detailed
specifications are provided in the ZF 4WG-92 TSC &
TB92-I4 Transmission/Transfer Box Repair Manual, JLG
P/N 8990495 (ZF P/N 5871 134 002) or ZF 4WG-98 TSC
& TB92-I4 Transmission/Transfer Box Repair Manual,
JLG P/N 8990517 (ZF P/N 5871 133 002).
The ZF 4WG-92/98 TSC Transmission used in this
vehicle is a four-speed configuration, chosen for its
compatibility with vehicle chassis and operating
requirements.
6.3 TRANSMISSION OPERATION
The transmission is mounted to the engine and the front
of the engine support structure by a mounting bracket
with rubber isolator pads. Power from the engine is
transmitted to the transmission by means of a torque
converter & flex plate, bolted directly to the engine
flywheel. Power is then transferred through the
transmission, which in turn, transmits power to the 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
rotates, forcing oil through the stator, which is held
stationary 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”)
systems, 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
transmission. 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 as part of the engine heat exchanger
assembly (radiator).
The transmission gear (“speed”) select lever, an electric
shift control, is located on the left side of the steering
column in the operator’s cab. Movement of the gear
select lever energizes the selected transmission shift
solenoid 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. The gear select lever movement
energizes 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 together and drive as a unit, providing
output power.
6.4 TRANSMISSION SERIAL NUMBER
The transmission serial number plate (1) is located on the
pump side (front) of the transmission at the bottom right,
just above the oil dipstick tube. Information specified on
the serial number plate includes the transmission model
number, the transmission serial number and other data.
Information on the serial number plate is required in
correspondence regarding the transmission.
WARNING:
DO NOT service the vehicle
without following all safety precautions as
outlined in the “Safety Practices” section of this
manual. Failure to follow the safety practices
may result in death or serious injury.
MU0930
1