Bendix-commercial-vehicle-systems ET-2 ELECTRONIC THROTTLE 6/04 User Manual download pdf

MACK

CAT

DETROIT

DIESEL

DESCRIPTION

The ET-2

™

is an electronic throttle. On electronically

controlled diesel engines, the ET-2

™

treadle fulfills the same

function as a conventional mechanical throttle. The ET-2

™

treadle controls engine speed by interacting with an

electronic fuel management controller on the engine, rather

than transmitting a mechanical force from the throttle pedal

to the engine governor.

The main components of the ET-2

™

throttle are a cast

aluminum mounting base and treadle, a rubber treadle cover,

a potentiometer (variable resistor), and a roller assembly.

The potentiometer is specific to each engine application.

OPERATION

The ET-2

™

treadle provides smooth, graduated throttle control

through the function of its variable resistor, or potentiometer.

The ET-2

™

treadle receives its supply voltage from the engine

control unit. The lever shaft connects the roller assembly

to the potentiometer, so that any movement of the treadle

rotates the potentiometer. As the potentiometer rotates,

its resistance changes. This way, the potentiometer

communicates the throttle position to the fuel control

system by changing resistance, returning more or less of

the supplied voltage back to the electronic engine controller.

If the driver does not request engine power, the throttle is in

the idle (or “closed throttle”) position. In this state, the

potentiometer significantly reduces the amount of supply

voltage returned to the engine control unit (See Figure 2).

As the driver depresses the ET-2

™

treadle, output voltage

increases (see Figure 3). The potentiometer allows an

increased amount of its supply voltage to return to the engine

control unit, which in turn increases the engine’s speed.

In the full (or “open throttle”) position, the driver has fully

depressed the ET-2

™

treadle. This is the state of least

potentiometer resistance. The ET-2

™

treadle returns the

maximum percentage of supply voltage to the engine control

unit (see Figure 2).

SD-15-4106

Engine Idle Throttle Full Throttle

Manufacturer (Closed) (Open)

CAT 13 - 21% 79 - 89%

Cummins 8 - 18% 70 - 80%

Detroit Diesel 6 - 14% 86 - 94%

Mack 10 - 20% 70 - 85%

FIGURE 2 - ET-2

™

TREADLE OUTPUT VOLTAGE, AS A

PERCENTAGE OF SUPPLY VOLTAGE

FIGURE 3 - ET-2

™

TREADLE OUTPUT VOLTAGE

CLOSED THROTTLE OPEN THROTTLE

ET-2

™

TREADLE

OUTPUT

VOLTAGE

CUMMINS

Bendix

ET-2

™

Electronic Treadle

CONNECTOR

FIGURE 1 - ET-2

™

ELECTRONIC TREADLE

TREADLE

COVER

CABLE ASSEMBLY

ROLLER

MOUNTING BASE

DOUBLE RETURN

SPRING

PIVOT SPRING

POTENTIOMETER

1 2 3 4 5 6 7 8

Summary of Contents

Page 1 - Electronic Treadle

1®8V1234567MACKCATDETROITDIESEL0VDESCRIPTIONThe ET-2™ is an electronic throttle. On electronicallycontrolled diesel engines, the ET-2™ treadle fulfill

Page 2 - PREVENTIVE MAINTENANCE

2FIGURE 4 - EXPLODED VIEWFigure 3 illustrates the relationship between throttle positionand engine RPM. Potentiometer performance will vary foreach e

Page 3 - FIGURE 6 - ET-2

3wear, or physical damage. Check end-to-end electricalcontinuity at terminals. NOTE: Potentiometer pinlocations will remain constant (see Figure 5).

Page 4 - TREADLE ELECTRICAL TEST

46. Record the output voltage when the pedal is in the idleposition (V1). Then slowly depress the pedal. Whenthe ohm meter shows that the resistance h

Page 5

5FIGURE 8 - ET-S™ TREADLE ELECTRICAL TEST SCHEMATIC FOR THE CATERPILLAR CONNECTORPEDALPOSITIONSENSOR(PWM).001µF(CABLE)POTENTIOMETER47,000 OHM ±5%RESI

Page 6 - CLEANING & INSPECTION

6INSTALLATION1. Install the assembled ET-2™ treadle on the vehicle.2. Reconnect the cable connector by plugging it into thepotentiometer’s integral co

Page 7

75. The installation of the remaining components is mucheasier if the inner and outer springs (12 & 13) arecompressed and caged. This can be done

Page 8

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Bendix-commercial-vehicle-systems ET-2 ELECTRONIC THROTTLE 6/04 User Manual

Browse online or download User Manual for Equipment Bendix-commercial-vehicle-systems ET-2 ELECTRONIC THROTTLE 6/04. Bendix Commercial Vehicle Systems ET-2 ELECTRONIC THROTTLE 6/04 User Manual

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