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Power Train - front loader

SMCS - 3000,4000,4800
SIS 2.0
General Information (RENR8865)
Illustration 1
Location of Power Train Components
(1) Diesel engine
(2) Torque converter
(3) Transmission
(4) Output transfer gears
(5) Rear final drives
(6) Rear drive shaft
(7) Front drive shaft
(8) Front final drives
Power from the diesel engine (1) is sent from the flywheel to torque converter (2). The
torque converter is splined to the engine flywheel. The torque converter is fastened to
transmission (3) by bolts. Power flows directly from the torque converter to the
transmission input shaft. The torque converter output gear is meshed to the transmission
input gear.
The transmission output shaft is connected to the input gear in output transfer gear case
(4) by splines. Power is sent through the input gear to the output gear. The output gear
sends power through rear drive shaft (6) to the rear differential. The output gear also
sends power to the front differential through front drive shaft (7). The bevel gear and
pinion of each differential sends the power to the final drives through the differentials and
through the sun gear shafts. Axle shafts transfer the power from final drives (5) and (8) to
the wheels.
SIS 2.0
Illustration 2
Block Diagram of the Power Train Electronic Control System
(9) Position sensor (left pedal)
(10) Transmission direction and speed control
(11) ET service connector
(12) CAT Data Link
(13) Caterpillar Monitoring System
(14) Caterpillar Monitoring System service connector
(15) Power train electronic control module (ECM)
(16) Auto/manual switch for the Autoshift control
(17) Transmission neutralizer override switch
(18) Variable shift control switch
(19) Minimum engine speed setting
(20) Engine
(21) Engine speed sensor
(22) Torque Converter
(23) Torque Converter output speed sensor
(24) Modulating valves (transmission clutch) (six)
(25) Transmission oil temperature sensor
(26) Transmission output speed sensors (two)
(27) Differential
(28) Transmission
Six hydraulically activated clutches in transmission (28) provide four forward speeds and
four reverse speeds. Speed selections and direction selections are made manually with
transmission direction and speed control (10). The autoshift control will make speed
selections if the machine is in automatic mode. The variable shift control uses the
position of the variable shift control switch and the engine speed in order to provide
alternate auto shift points.
The power train electronic control system electronically controls transmission shifts. The
power train electronic control system shifts the transmission. In order for the transmission
to be shifted to the desired speed and the desired direction, power train ECM (15)
receives the operator input from transmission direction and speed control (10) and the left
brake pedal position sensor. The power train ECM signals the modulating valve
(transmission clutch) of the speed clutch that is selected. The power train ECM signals
the modulating valve (transmission clutch) of the direction clutch that is selected. The
output signal energizes the solenoids of modulating valves (transmission clutch) (24) that
are selected. The energized modulating valves (transmission clutch) electronically
SIS 2.0
modulate the oil pressure of the clutches that are selected. The power train ECM can
request automatic shifts. The power train ECM uses the following input signals to ensure
steady engagement of the clutches: engine speed sensor (21), torque converter output
speed sensor (23), transmission speed sensors (26) and transmission oil temperature
sensor (25) .
The power train ECM also controls the following functions: neutral start, ride control,
backup alarm, auto shift control, variable shift control, secondary steering, speed limiter,
parking brake interlock and transmission neutralizer.
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