Section XVIII. REPAIR OF ACCELERATOR RELAY

TM 10-3930-609-35

b. If additional cleaning is required, wipe parts with

d. Replace coils if damaged due to overheating or

cloth moistened with SD.

if resistance measured is not within specified limits.

3-124.

Inspecting Parts of Forward and Reverse

3-126. Reassembly of Forward and Reverse Relay

Relay

(fig. 3-23)

a. Inspect all threaded parts and tapped holes for

a. Mount molded contact supports on magnet

stripping or other thread damage.

frames with flat head screws and lockwashers.

b. Inspect busses, contact arms, contact supports,

b. Insert coil cores through spring washers and

armature supports, switch brackets, magnet frames and

through coils and secure to magnet frames with screws

armatures for distortion or other damage.

and lockwashers.

c. Inspect contacts on contact arms and on contact

c. Mount brackets and armature supports to

supports for wear, pitting or burning.

magnet frames with screws, flatwashers and

lockwashers.

d. Inspect shunts for fraying and for security of

d. Install armatures on armature supports; then,

terminations.

apply springs, cup washers and self-locking nuts to

e. Inspect molded contact supports for cracks or

studs of armature supports.

other damage.

e. Mount switches on switch brackets with screws,

f. Inspect all springs for distortion.

flatwashers and lockwashers.

g. Using an ohmmeter or test light, check switches

f. Install contacts on contact supports and on

for operation as switch plungers are depressed.

contact arms and secure with nuts.

h. Using an ohmmeter, check that each coil has a

g. Place contact arms on studs in armatures; then,

resistance of 28 2.8 ohms at 70 . Also inspect coils

place spring and cup washer on each stud, and insert

for damage due to overheating.

cotterpin through holes in studs. Spread prongs of

cotterpins just sufficiently to retain cotterpins.

3-125.

Repair and Replacement of Forward and

h. Secure one end of each shunt to each contact

Reverse Relay Parts

arm with a screw, flatwasher and lockwasher. Use a

a. If contacts are slightly pitted or burned, smooth

screw and lockwasher to secure other end of each shunt

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

and bus to magnet frame.

sandpaper. Discoloration on contacts does not affect

i. Mount upper contact support on molded contact

proper operation and need not be removed if contacts

supports with screws and lockwasher.

are not pitted or burned. Do not remove more metal

than necessary to obtain smooth contact surfaces.

j. Mount lower contact supports on molded contact

supports with screws and lockwashers; then, attach both

b. Repair minor thread damage with a tap or

ends of bus to lower contact supports with screws and

thread chaser.

lockwashers.

c. Replace all cracked or distorted parts.

Section XVIII. REPAIR OF ACCELERATOR RELAY

3-127. Description of Accelerator Relay

3-129. Disassembly of Accelerator Relay (fig. 3-24)

a. Remove screws and lockwashers which secure

The accelerator relay comprises a coil and an armature

stop and lower contact bracket to molded contact

and a form A contact. An interlock switch is mounted on

support.

the magnet frame.

b. Remove screw, lockwasher and flatwasher

which secure shunt to contact arm and remove screw

3-128. Removal of Accelerator Relay

and lockwasher which secure shunt and bus to magnet

frame; then, remove shunt and bus.

Removal of the accelerator relay from the control panel

c. Remove cotterpin, cup washer and spring from

is recommended for repair in accordance with the

stud on armature and lift off contact arm.

following instructions. Refer to paragraph 2-28 for

removal procedure.

3-43