BENDIX BW1650 User's Manual

BENDIX Electronic Treadles User's Manual - BW1650.
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®

8V

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2

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6

7

MACK

CAT

DETROIT

DIESEL

0V

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

OR

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

0.718772s