1
®
SD-15-4111
MOUNTING
PLATE
FIGURE 3 - OUTPUT VOLTAGE
OPEN THROTTLE
(FULL)
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0V
ET-S
™
TREADLE
OUTPUT
VOLTAGE
ENGINE
MAX
RPM
IDLE
CLOSED THROTTLE
(OPEN)
MOUNTING
PLATE
POTENTIOMETER
CONNECTOR
FIGURE 1 - ET-S
™
AND ET-S2
™
ELECTRONIC TREADLES
CATERPILLAR
5V
8V
CUMMINS
DETROIT
DIESEL
DESCRIPTION
The ET-S
™
and ET-S2
™
treadles are engine compartment
bulkhead mounted electronic treadles. On electronically
controlled diesel engines, the electronic treadle fulfills the
same function as a conventional mechanical throttle.
However, rather than transmitting a mechanical force to the
engine governor, the electronic treadle controls engine speed
by supplying a variable electrical voltage to the engine’s
electronic controller.
The main components of the ET-S
™
and ET-S2
™
treadles
are: a mounting plate, suspended treadle, potentiometer
(variable resistor), actuator body and base. The selected
potentiometer, chosen for a specific engine application,
provides the electrical link to the engine control system.
OPERATION
The electronic treadles provide smooth, graduated throttle
control through the function of its potentiometer (variable
resistor). The drive shaft of the cam follower assembly
transfers any movement of the treadle to the potentiometer.
ACTUATOR BASE
TREADLE
TREADLE
Bendix
®
ET- S
™
& ET-S2
™
Suspended Electronic Treadle
ACTUATOR BODY
DETROIT
CATERPILLAR
CUMMINS
DIESEL
CLOSED
THROTTLE
7 - 18%
10 - 20%
5 - 17%
IDLE (OPEN)
OPEN
THROTTLE
74 - 90%
75 - 90%
70 - 81%
(FULL)
FIGURE 2 - OUTPUT VOLTAGE, AS A PERCENTAGE OF
SUPPLY VOLTAGE
ET-S2
™
TREADLE
TREADLE
TREADLE PIVOT PIN
MOUNTING
PLATE
POTENTIOMETER
ET-S
™
TREADLE
