Table 2-4. Semi-trailer Troubleshooting
Brakes will not hold.
Worn out brake lining.
Replace. (para 7-31.
Leaky relay emergency valve.
Brake action slow.
Defective brake air chamber.
Replace (para 7-7).
Slack adjuster travel too long.
Adjust check to see if within spec.
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
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).
Section III. GENERAL MAINTENANCE INSTRUCTIONS
the point in repair instructions where the inspection must
This section provides general cleaning,
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
covered with that component in the applicable sections of
(2) Visually and by hand inspect all working
parts such as doors, panels, lids (or tops for wear,
damage or looseness.
2-9. General Cleaning Instructions
Prior to Removal or Disassembly of Major
(1) Visually inspect all internal wiring for
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.
(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
to repair tapped holes. Discard and replace all hardware
Do not use compressed air to blow out the
that has defective threads.
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
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.
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
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.