Table 2-4. Semi-trailer Troubleshooting

Table 2-4. Semi-trailer Troubleshooting

Malfunction

Probable Cause

Corrective Action

Brakes will not hold.

Worn out brake lining.

Replace. (para 7-31.

Leaky relay emergency valve.

Replace, repair.

Brake action slow.

Defective brake air chamber.

Replace (para 7-7).

Slack adjuster travel too long.

Adjust check to see if within spec.

(para 7-3).

Brakes grab.

Loose brake lining.

Inspect if still useable realign and

adjust. (para 7-31.

Trailer pulls hard.

a. Undercarriage assy. loose.

a. Check mounting bolts of assy. to

frame. Tighten, if loose to the

torque spec.

b. Brakes dragging.

b. See brakes drag malfunction.

c. Wheels not aligned to trailer.

c. Check wheel alignment. (para 7-8).

d. Bent or broken spring (for leaves).

d. Replace. (para 7-9).

U bolt.

Section III. GENERAL MAINTENANCE INSTRUCTIONS

the point in repair instructions where the inspection must

2-8.

General

be performed.

This section provides general cleaning,

Visual Inspection.

inspection and repair instructions that are common to

(1) Visually inspect all external surfaces of

components used on the mobile substation.

all enclosures, trailer bed and frame, trailer running gear

Special cleaning, inspection and repair

and accessories for badly dented, bent or weathered

instructions applicable to any individual component is

spots.

covered with that component in the applicable sections of

(2) Visually and by hand inspect all working

this manual.

parts such as doors, panels, lids (or tops for wear,

damage or looseness.

2-9. General Cleaning Instructions

Electrical Parts.

Prior to Removal or Disassembly of Major

(1) Visually inspect all internal wiring for

Components.

frayed or damaged insulation and poor connections to

(1) Clean the exterior of the trailer, metal

terminal lugs and terminals.

enclosures and external mounted accessories of road

(2) Visually inspect all buses for cracks and

grime, dirt, oil and grease, and other foreign matter.

discoloration.

(2) Clean the interior of high and low

voltage section and their compartments thoroughly using

2-11. General Repair Instructions

a vacuum cleaner and clean rags.

Thread Repair. Use proper size tapping tool

CAUTION

to repair tapped holes. Discard and replace all hardware

Do not use compressed air to blow out the

that has defective threads.

compartments.

Bearing Replacement. Do not press on outer

Prior to Removal or Disassembly of Electrical

race of bearing when installing on shafts. Do not press on

Components. Clean off excess oil and dirt. Wipe clean

inner race of bearings when installing in a housing.

with lint free cloth dampened with cleaning solvent (Fed.

Electrical Parts. Replace wire with frayed or

Spec P-D-680).

damaged insulation. Replace cracked or broken terminal

Gaskets and Seals.

boards, lugs, terminals and clamp connectors. Record

(1) Clean all old gasket particles and

bus deficiency for replacement.

weather seals from mating surfaces.

Trailer.

Straighten, clean and repaint

(2) Discard and replace all non-reusable

accessories and weathered spots of trailer bed and frame.

type and damaged weather seals and gaskets.

Record running gear deficiency to be repaired. Schedule

them for replacement or repair.

2-10. General Inspection Instructions

General. Perform an inspection of all parts

as soon as possible after cleaning. Instructions for

specific inspection procedures are included in the text at

Section IV. REMOVAL AND INSTALLATION OF MAJOR COMPONENTS

2-12. General

This section contains instructions for removal and

to facilitate repair and overhaul instructions which are

installation of major components of the mobile substation

covered in subsequent sections of this manual.

2-3