JLG Triple-L Operator Manual - Manual (Page 47)

SECTION 4 - SERVICE AND MAINTENANCE
3121224 – Triple-L-Trailer – 4-7
Brake Shoes and Drums
Properly functioning brake shoes and drums are essential
to ensure safety. You must have your dealer inspect these
components at least once per year, or each 12,000 miles.
The brakes should be adjusted (1) after the first 200 miles
of operation when the brake shoes and drums have
"seated," (2) at 3000 miles intervals, (3) or as use and per-
formance requires.
Manually Adjusting Brake Shoes
The manually adjusted brakes should be adjusted in the
following manner:
1. Jack up the trailer and secure it on adequate capac-
ity jack stands.
2. Be sure the wheel and brake drum rotate freely.
3. Remove the wheel and brake drum. Because of the
special stub axle arrangement, adjustment cannot
be made through the backing plate.
4. With a screwdriver or standard adjusting tool, rotate
the starwheel of the adjuster assembly to expand
the brake shoes. Adjust the brake shoes out until the
pressure of the linings against the drum produces a
slight drag.
5. Remount the wheel and brake drum.
6. Repeat the above procedure on all brakes.
Lower the trailer to the ground.
E LECTRIC B RAKES (O PTIONAL )
(See Figure 4-5.)
The electric brakes on a trailer are similar to the drum
brakes on an automobile. The basic difference is that the
automotive brakes are actuated by hydraulic pressure
while electric trailer brakes are actuated by an electro-
magnet. With all of the brake components connected into
the system, the brake will operate as follows:
When the electrical current is fed into the system by the
controller, it flows through the electromagnets in the
brakes. The high capacity electromagnets are energized
and are attracted to the rotating armature surface of the
drums, which moves the actuating levers in the direction
that the drums are turning.
The resulting force causes the actuating block at the shoe
end of the lever to push the primary shoe out against the
inside surface of the brake drum. The force generated by
the primary shoe acting through the adjuster assembly
then moves the secondary shoe out into contact with the
brake drum.
Increasing the current flow to the electromagnet causes
the magnet to grip the armature surface of the brake drum
more firmly. This results in increasing the pressure against
the shoes and brake drums until the desired stop is
accomplished.
Brake Controller - A tow vehicle brake controller is
required. These controllers have gain control to vary the
amount of current to the brakes, and a level control which
sets the controller's inertia sensor to sense deceleration.
The level adjustment also can be used to vary when the
trailer braking is felt. The gain or output control adjust-
ment usually controls the maximum amount of amperage
available to the brakes. This can be adjusted for varying
trailer loads.
The electric brakes that operate in conjunction with the
tow vehicle brakes must be “synchronized” so that brak-
ing is properly distributed to the tow vehicle brakes and
the trailer brakes. For proper operation and synchroniza-
tion, read and follow the axle/brake and the brake control-
ler manufacturers’ instructions.
Brake Cleaning and Inspection - Your trailer brakes must
be inspected and serviced at yearly or 12,000 miles inter-
vals or more often as use and performance requires. Mag-
nets and shoes must be changed when they become
worn or scored thereby preventing adequate vehicle brak-
ing. Clean the backing plate, electromagnet, and brake
shoes. Make certain that all the parts removed are
replaced in the same brake and drum assembly. Inspect
the magnet arm for any loose or worn parts. Check shoe
retractor springs, hold down springs, and adjuster springs
for stretch or deformation and replace if required.
Shoes and Linings - A simple visual inspection of your
brake linings will tell if they are usable. Replacement is
necessary if the lining is worn (to within 1/16” or less),
contaminated with grease or oil, or abnormally scored or
gouged. It is important to replace both shoes on each
brake and both brakes of the same axle. This is necessary
to retain the “balance” of your brakes.