CONTACTS

6-240. ELECTRICAL CONTROL ADJUSTMENTS.

(ohmmeter) or maximum brightness (continuity tester)

6-241. GENERAL. The SCR control pack which

when in the neutral position.

controls creep speed, acceleration time, the shorting

6-235. CONTACTS. The contacts are silver and need

contactor time delay, current limit, and plugging severity

only be replaced when worn thin. Do not file contacts;

is adjusted for each truck during manufacture.

discoloration and slight pitting of the contacts is not

Replacement of control components or motors may

harmful. When contacts need replacing, the contact

require readjusting of the control pack (7, figure 7-10)

module is replaced as a unit, along with its cam.

for proper truck operation. Adjustment may also be

Proceed as follows:

required when the nature of operation or type of

(1) Remove the module retaining screw (24),

materials handled change. The change from a lead-acid

and remove the individual modules and cams, keeping

to a nickel-iron alkaline battery will require adjustment

the parts in order to facilitate reassembly.

(para 6-250).

6-242. ADJUSTMENTS. The SCR control pack cover

(2) When reassembling, make sure the cams

is removed and exposes five trimmers. Clockwise

and contact modules are replaced in order. Also make

rotation will provide an increase in the function being

sure the orientation of the index line on the cams and

adjusted and counterclockwise a decrease. The SCR

contact modules is the same as in the above diagram.

trimmers provide fifteen turn to go from one end of the

6-236. RETURN SPRING. Proceed as follows:

trimmer range to the other. At each end the adjusting

(1) To replace a broken return spring,

screw will "slip" to prevent damage to the threads. The

proceed with the disassembly as in the contacts section.

field weakening pack (20, figure 7-3) is provided with

drop-out and pick-up single turn trimmers, each having

(2) Gently pry off detent cam housing (35)

a locknut.

and cover (33), and the spring return housing (26).

NOTE

(3) Slide off the shaft bearing (36), spring

Make all adjustments except where noted in the

drive (37) and defective spring (39).

following sequence. Adjustments must be made

with a fully charged battery.

(4) With the shaft oriented so the spring

drive

6-243. PREPARATION OF TRUCK. Make adjustments

is directly opposite the detent cam housing

(35)

to the electrical control circuits as follows:

protrusion, slide the new return spring (39) on the

shaft

(1) Raise drive wheels of truck off floor.

so that both spring ends are above the detent

cam

Support securely.

housing (35) protrusion.

(2)

Remove rear control panel cover (para 6-

(5) Using a screwdriver, load the spring by

28).

placing the top end of the return spring below the detent

cam housing protrusion. Replace the spring drive (37)

(3) Remove the SCR control pack cover (7,

so its hub is adjacent to the detent cam protrusion.

figure 7-10).

(6) Replace the shaft bearing (36), spring

(4) Disconnect the heavy cable connecting

return housing (26), detent module and cover.

the hydraulic pump relay IMP (2, figure 7-3) and the

6-237. DIRECTIONAL CONTROL SWITCH.

shorting contactor SC relay (17).

Connect a DC

6-238. DISASSEMBLY. Proceed as follows:

ammeter and a shunt between the end of the removed

(1) Remove cover (11, figure 7-12) attached

cable and the terminal from which it was removed.

with two screws ( 12), washers (13), and liner (14).

(5)

Remove truck floor plate (para 627).

(2) Remove screws attaching sensitive

switches (18) to bracket (19) and remove switches.

(6) Disconnect wiring harness at the master

cylinder brake light switch (9, figure 7-29) connector

(3) Remove screws holding housing bracket.

plug. The plug contacts are arranged in two rows of

Remove housing bracket (10).

three contacts. Connect, with a jumper wire, the outer

contacts of one row in the harness end plug. With all

(4) Remove springs (20). Remove two clips

switches in operating position, check for stoplight. If

(22) attached with screws, and remove pins (21) and

stoplight lights, remove jumper and connect to outer

arm assemblies (23).

contacts of other row. The jumper in correct location will

lock out the brake switch in the travel motor circuit.

NOTE

(5) Remove screw and washers securing

carrier assembly to shaft (24). Remove shaft and

If wire harness leads are numbered, jump wire

spacer (26) from housing (28).

70 to wire 94. See wiring schematic (figure 41).

6-239. ASSEMBLY. Reverse disassembly procedures.

6-49