Disassembly. - TM-10-3930-620-340049

(5) Check for evidence of wear, binding,

assembly (5, fig. 3-11) in the box touches the down stop

damage, and bending of parts that might impair

screw (191 when the accelerator bearing is within 1/ inch

operation.

of the toe plate (or fixture).

d. Disassembly.

(4) With the pedal depressed fully, adjust the

potentiometer for an ohmmeter reading of 30 to 50

(1) Disassemble accelerator pedal and linkage

ohms. Tighten the set screw (13) in the actuator to

according to figure 3-10.

securely engage the potentiometer shaft.

(2) Disassemble speed control box assembly

(5) With the pedal in the up position, a reading

according to figure 3-11.

e. Reassembly.

of 15, 000 to 16, 000 ohms should be obtained on the

ohm meter.

(1) Reassemble speed control box assembly

(6) Adjust position of microswitch (11) so its

according to the reverse of figure 3-11 and as follows:

(a) Install the microswitch (11) with the

plunger operates when the pedal is l/4 inch from the full

up position.

common terminal toward the rear of the box.

(7) Recheck the readings of steps 4 and 5 and

(b) Install the potentiometer (14) with the

the microswitch operation of step 6.

terminals toward the bottom of the box.

Note.

P1erform the inching control

adjustment this time.

Refer to

(37) to the center terminal of the potentiometer. Connect

paragraph 3-7d.

the yellow wire to the terminal nearest you.

(8) Disconnect ohmmeter and reconnect wires

(2) Reassemble the accelerator pedal and

to potentiometer.

linkage according to the reverse of figure 3-10.

(9) Remove the toe plate fixture and install the toe

f. Adjustment.

To aid in adjustment it is

plate (TM 10-3930-620-12).

recommended that a toe plate fixture be substituted in

(10) Install the box cover (3) and gasket (4) using

place of the toe plate. The fixture should be the same

the two screws (1) and lock washers (2 .

thickness as the toe plate and large enough so the

3-7. Control Unit

accelerator rod bearing (13, fig. 3-10) will make contact

a. Voltage Test. This test should be made a with a

with it. Secure the fixture to the right hand mountings on

fully charged battery.

Set the voltmeter to the

the truck frame.

appropriate scale for each test. Connect the voltmeter

(1) Disconnect wires from speed potentiometer

negative and positive leads according to the - and +

(14. fig. 3-11 ). Connect ohmmeter between center

indicators given for each measurement. (fig. 3-12.)

terminal and terminal nearest you.

Note. 'The seat must be depressed and

(2) Loosen the set screw (13) in the actuator

emergency stop switch released when

arm 116) so the potentiometer shaft is free. .

performing these tests.

(3) Depress the accelerator pedal. Adjust the

yoke positions on the yoke rod (5, fig. 3-10) so the arm

3-21