TM-9-2330-238-14

CHASSIS, SEMITRAILER: 6-TON, 4-WHEEL M295A1; SEMITRAILER, VAN: EXPANSIBLE, 6-TON, 4-WHEEL M313; SEMITRAILER, VAN: SHOP, FOLDING SIDES, 6-TON, 4-WHEEL M447 AND M447C; SEMITRAILER, VAN: REPAIR PARTS, SHOP EQUIPMENT, 6-TON, 4-WHEEL M749; SEMITRAILER, VAN: REPAIR PARTS STORAGE, 6-TON, 4-WHEEL M750

TECHNICAL MANUAL; OPERATOR’S, ORGANIZATIONAL, DIRECT SUPPORT, AND GENERAL SUPPORT MAINTENANCE MANUAL

JULY 1992

TM-9-2330-238-14 - Page 188 of 462

TM 9-2330-238-14

4-44. RELAY VALVE MAINTENANCE.

This Task Covers:

a.

Operating Test

c.

Removal

b.

Leakage Test

d.

Installation

Initial Setup:

Equipment Conditions:

MateriaIs/Parts:

●

Semitrailer coupled to towing vehicle with airbrake

●

Dishwashing compound (Item 6, Appendix E)

system fully charged (para 2-10).

●

Marker tags (Item 15, Appendix E)

Tools/Test Equipment:

●

Antiselzing tape (Item 16, Appendix E)

• General mechanic’s tool kit

●

Two Iockwasher

Personnel Required:

Two

1.

Depress and hold brake pedal in towing vehicle

and check to see if brakes apply properly,

2.

Release brake pedal and check to see if air

pressure is released properly.

3.

With semitrailer airbrake system fully charged,

close shut-off valve in emergency line on towing

vehicle.

4.

Disconnect EMERGENCY air coupling (1) and

check to see if semitrailer brakes apply automati-

cally.

5.

Connect EMERGENCY air coupling (1) to semi-

trailer and open shut-off valve in emergency line

on towing vehicle. Check to see if semitrailer

brakes release automatically.

b. LEAKAGE TEST

1.

Apply soap and water solution to relay valve cover flanges (3) and fittings (5).

2.

If leakage is detected, tighten nuts (7) on cover flanges (3).

3.

Apply soap and water solution to exhaust port (8). Depress towing vehicle brake pedal and check for leakage.

4.

Apply soap and water solution to exhaust port (8). Release towing vehicle brake pedal and check for leakage.

TA701990

4-90