FORWARD AND REVERSE RELAYS.

reversing the disassembly procedure.

(1)

Disconnect all external leads to contactor.

6-227.

MASTER SWITCH AND PUMP MOTOR

RELAYS.

(2) Remove snap switch (1, figure 7-7) from

a. General. All trucks have one pump contactor

hinge bracket (I 11).

fitted with a circuit interlock which energizes the

hourmeter. If a truck has a second (optional) pump, the

(3) Disconnect

connector

(7),

remove

number two pump contactor will not have an interlock.

retaining snap ring and take off rocker arm lever (25)

Otherwise both contactors will be the same.

with movable contact (20). Take contact from rocker

arm lever. Take washer, timing actuator (28) from base

6-228. DISASSEMBLY. Disassemble only as far as

assembly (29).

necessary to repair, as follows:

(1) Disconnect all external leads to contactor.

(4) Remove screws

and

take

stationary

Remove contactor only if necessary.

contacts (15) from base (29).

(2) To replace finger contact (figure 74),

(5) Remove screw which holds coil (42) to

remove special nuts and lock washers and remove

magnet frame (45). Remove coil.

contact tops.

6-220.

ASSEMBLY.

Assemble the contactor by

(3) To replace coil (18), remove spring guide

reversing the disassembly steps.

(14), spring (12) and armature (11). Take out screw

above coil and remove two spring washers, pole face

6-221. FORWARD AND REVERSE RELAYS.

and assembly, and coil.

6-222. DISASSEMBLY. Disassemble contactor only

6-229. ASSEMBLY. Assemble contactor by reversing

as far as necessary to make repairs as follows:

steps above, observing the following recommendations.

(1) Disconnect all external leads.

6-230. STEERING RELAY.

6-231. DISASSEMBLY. Proceed as follows:

(2) Disconnect connector (I, figure 7-8),

(1) Disconnect leads to contactor. Remove

remove snap ring and take off rocker arm lever (16).

screw and washer (2, figure 7-6), and stationary contact

Remove both movable contacts (14).

(1).

(2) Remove nut (5) and insulator (10).

(3)

Take washer, timing actuator (19) from

Remove contact bar (4).

base (20).

(3) Remove leads to coil (19). Remove nut

(5) and screws (17), carefully lift interfering parts out of

(4) Remove screws, and take stationary

way and remove coil.

contacts (9) from base.

6-232. ASSEMBLY. Reverse procedure above.

6-233. ACCELERATOR CONTROL.

(5) Remove screw which holds coil (33) to

6-234. POTENTIOMETER REPLACEMENT. Proceed

magnet frame (36) and remove coil.

as follows: (figure 7-11).

(1) Remove

potentiometer

wires

from

6-223.

ASSEMBLY.

Assemble the contactor by

terminal strip (19).

reversing the disassembly procedure.

6-224. FIELD WEAKENING RELAY.

(2) Loosen allen set screw (22) which secures

6-225. DISASSEMBLY. Disassemble only as far as

potentiometer (21) to potentiometer drive and remove

required to perform needed repairs as follows:

potentiometer.

(1) Disconnect all external leads to contactor.

(3) Before installing new potentiometer

(2) Remove connector (1, figure 7-9), and

connect an ohmmeter or continuity tester between single

movable contact (14). Take off snap ring and take

terminal on top of potentiometer and center terminal of

rocker arm lever (19) from base (23).

bottom three terminals.

Adjust potentiometer for

minimum resistance (ohmmeter) or maximum

(3) Remove

screw

and

take

stationary

brightness (continuity tester).

contact (9) from base.

(4) Install potentiometer and tighten allen set

(4) Remove screw, and take coil (36) from

screw. (Make sure tab on side of potentiometer is in

magnet frame (39).

notch in bracket). Recheck potentiometer adjustment.

The potentiometer should exhibit minimum resistance

6-226.

ASSEMBLY.

Assemble the contactor by

6-48