PRIMARY POWERTRAIN SYSTEM CONTINUED
Torque Converter Output Speed Sensor provides the transmission ECM with the torque converter output
speed and the transmission input shaft speed of the transmission.
Auto/Manual/VSC Switch allows either manual operation or autoshift operation. The switch also has a vari-
able shift control (VSC) position which allows the transmission to shift at lower speeds.
Downshift Switch The downshift switch is located on the lift control lever. The downshift switch is used to
downshift the transmission manually. The downshift switch can be used when the machine is in any mode of
FINAL DRIVE AND UNDERCARRIAGE
Differential and Final Drives
Engine power is transmitted to the front and rear differentials by the front and rear driveshafts. The differential
divides and balances power that is sent to the wheels. Power is transmitted from the differential to the axles (final
drive). The wheels bolt to the axles.
When the machine is moving in a straight direction with the same amount of traction provided to each drive wheel,
and the same amount of torque is delivered to each wheel. When the machine is in a turn, the outside wheel turns
more easily and has to travel further than the inside wheel. The inside wheel is more resistant than the outside
wheel. This resistance causes different torque on the opposite sides of the differential. The outside wheel starts to
turn faster than the inside wheel yet the same amount of torque is still sent to the inside and outside wheels.
When one wheel has more traction than the other wheel, the operation of the differential is identical to the opera-
tion of the differential during a turn. The same amount of torque is sent to both wheels. This torque is only equal to
the amount of torque that is necessary to turn the wheel with the least resistance. The action of the differential can
cause the drive to be lost in adverse ground conditions if the resistance under one wheel is low. In these circum-
stances, all the drive torque will be transferred to the wheel with the least resistance.
Do not engage the differential lock while the machine is moving. Engaging the differential
lock can limit steering control. Use extreme caution when driving with the differential lock
engaged. Failure to follow this warning may result in serious injury or death to personnel
and/or damage to equipment.
The differential for the front axle is equipped with a differential lock, which allows the axle shafts to be locked
together. Both wheels can then rotate at the same speed and torque regardless of different ground resistance (trac-
tion) between the wheels. The differential lock is controlled by a two-position foot switch that is located on the floor
of the operator station. The foot switch for the differential lock control operates a solenoid valve. Hydraulic oil is
supplied to the solenoid valve from the hydraulic Implement pump. The differential lock is engaged by oil pressure
when the foot switch is held down. Hydraulic oil pressure from the solenoid valve engages a piston at the differen-
tial, locking the differential lock. The differential lock is disengaged by spring force when the foot switch is released
allowing torque to equalize between the wheels.