Section XVII. REPAIR OF FORWARD AND REVERSE RELAY

TM 10-3930-609-35

c. Inspect contacts for wear, pitting and burning.

b. Place spring washer and coil on frame assembly

and secure with retaining ring.

d. Inspect shunt for fraying and for security of

c. Screw threaded ends of posts into frame

terminations.

assembly; then, secure flatwashers to upper ends of

e. Inspect springs for elongation or other distortion.

posts with screws.

f. Using an ohmmeter, check that resistance of

d. Mount U-shaped contact support on base with

pump relay coil is 28.2 2.8 ohms and that resistance of

screws and flatwashers.

master switch relay coil is 46.9 4.7 ohms at 70 .

e. Mount contacts on U-shaped contact support

Also inspect coil for damage due to overheating.

and on flat contact support with lockwashers and self-

locking nuts.

3-118. Repair and Replacement of Pump Relay and

Master Switch Relay Parts

f. Assemble flat contact support on armature;

insert pin through armature and contact support; and,

a. If contacts are slightly pitted or burned, smooth

assemble cup washer, spring, cup washer and retaining

up surfaces with a file. Do not use emery cloth or

ring on pin.

sandpaper. Do not remove more metal than required to

obtain smooth contact surfaces.

g. Mount guide on armature with two screws and

secure support to frame assembly with two screws.

b. Repair minor thread damage with a tap' or

thread chaser.

h. Insert screw through fulcrum, through guide and

through support; then, install spring and cup washer on

c. Replace all cracked or distorted parts.

screw and secure with self-locking nut.

i. Secure one end of shunt together with terminal

3-119. Reassembly of Pump and Master Switch

to frame assembly with screw and lockwasher; and,

Relays (fig. 3-22)

secure other end of shunt to flat contact assembly with

a. Assemble frame assembly to base with screws

screw and lockwasher.

and washers.

Section XVII. REPAIR OF FORWARD AND REVERSE RELAY

busses to magnet frame; then, remove shunts and

3-120. Description of Forward and Reverse Relay

busses.

The forward and reverse relay comprises two coils and

two armatures and two sets of form C contacts. The two

c. Remove cotterpins, cup washers and springs

armatures operate independently; however, interlock

from studs on armatures and lift off right hand and left

switches are mounted on the magnet frames and are

hand contact arms.

used in the circuit to prevent both coils from being

d. If contacts on contact arms or on contact

energized simultaneously.

supports require replacement, remove nuts from

threaded studs on contacts and withdraw contact from

3-121. Removal of Forward and Reverse Relay

arms and supports.

Removal of the forward and reverse relay from the

e. Remove screws, lockwashers and flatwashers

control panel is recommended for repair in accordance

which secure switches to brackets and remove switches.

with the following instructions. Refer to paragraph 2-29

f. Remove selflocking nuts, cup washers and

for removal procedure.

springs from studs on armature supports; and, withdraw

armatures from armature supports.

3-122. Disassembly of Forward and Reverse Relay

g. Remove screws, lockwashers and flatwashers

(fig. 3-23)

which secure brackets and armature supports to magnet

a. Remove screws, and lockwashers which secure

frames; and, withdraw brackets and armature supports.

upper contact support and two lower contact supports to

h. Remove screws and lockwashers from center of

molded contact support.

Remove screws and

coil cores; then, remove coil cores, spring washers and

lockwashers which secure bus to lower contact supports

coils from magnet frames.

if separation of lower contact supports is required.

b. Remove screws, lockwashers and flatwashers

which secure shunts to contact arms, and remove

screws and lockwashers which secure shunts and

3-41