POWER TRAIN 777 SERVICE MANUAL
7-10 Published 10-01-2012, Control # 045-08
ENGINE THROTTLE ADJUSTMENT -
CATERPILLAR 3176B AND 3176C ENGINES
The throttle assembly for the Caterpillar 3176B and 3176C
engines consists of a hand throttle controller in the left
console, a foot pedal on the cab floor, a foot throttle controller
in the right console, a converter board with potentiometers,
associated linkage, and electrical connections.
In the right console, a reach rod connects the foot pedal
assembly to the lever on the foot throttle controller. An
electric cable connects the foot throttle controller in the right
console to the hand throttle controller in the left console.
Foot Throttle Linkage Adjustment
See Figure 7-4 for following procedure.
1. Install spring clip (1) and rod end (2) on controller lever
at dimension shown in View A and securely tighten jam
nut (3).
2. Insert a 3/16 in. (5 mm) thick shim or piece of floor mat
between foot pedal and cab floor.
3. Press foot pedal down fully to HIGH IDLE position
against shim or floor mat.
4. Adjust reach rod (4) and rod end (5) so controller lever is
rotated fully to HIGH IDLE position. Securely tighten jam
nuts (6) to lock adjustment.
NOTE: Controllers have internal stops at high and low idle.
5. Release foot pedal to low idle position.
6. Adjust return springs so there is sufficient force to raise
pedal and rotate controller lever to low idle.
7. Adjust pedal stop screw (7). Screw must be tight against
cab floor and there must be 1/8 in. (31 mm) gap between
pin (9) and rear end of slot in rod end (5). Securely
tighten jam nut (8).
8. With foot pedal in LOW IDLE position, distance from top
of pedal to cab floor should be 3-15/16 in. (100 mm).
Engine Speed Calibration
See Figure 7-7 while calibrating engine speed.
Engine speeds are calibrated on the converter board
mounted in the left console near the hand throttle controller.
This board converts 0 – 8 VDC analog signal to 5.0 VDC
PVM signal at 500 Hertz.
Engine speeds at minimum and maximum throttle were
adjusted at the factory and should not need further attention.
Adjustment is required if the control is replaced. Adjustments
are to be completed in the sequence given in this topic.
NOTE: A digital VOM meter with the capability of
displaying percent modulation is needed to set duty
cycle percentages (example: FLUKE 87 True RMS
Multimeter).
1. Stop engine.
2. Remove cover plate and hand throttle controller from left
console. Move to side for access to converter board. Be
careful not to damage electric wires.
3. Connect mulitmeter to 0 and 68K terminals on converter
board.
4. Turn cab power switch ON and set engine RUN/STOP
switch to RUN to supply power to converter board. Do
not start engine.
5. Move hand throttle to minimum (low idle) position.
6. Set threshold potentiometer to duty cycle indicated in
Table 7-6.
7. Move hand throttle to maximum (full throttle) position.
8. Set span potentiometer to duty cycle indicated in Table
7-6.
9. Remove multimeter and start engine.
10. Verify calibration at minimum and maximum throttle
positions while monitoring ENGINE SPEED on digital
display in operator’s cab.
Adjust threshold and span potentiometers as needed so
that engine speed is within ranges specified in Table 7-6.
11. Reinstall cover plate and hand throttle controller on
console.
Table 7-6
Throttle Settings
Throttle Setting Engine Speed Duty Cycle Voltage
Minimum 975±25 rpm 15%
0.23 VDC nominal (0.25 max) @ 1.0 MA sink current
0.65 VDC nominal (0.75 max) @ 10.0 MA sink current
Maximum 2110±10 rpm 82%
4.0 VDC (minimum)
5.0 VDC (maximum)
To Next Page
Loading...
Need help?
General
