JLG Triple-L Operator Manual - Manual (Page 50)

SECTION 4 - SERVICE AND MAINTENANCE
4-10 – Triple-L-Trailer – 3121224
Hydraulic (Surge) Brakes (Option)
(See Figure 4-6.)
If your trailer has hydraulically-operated brakes, they func-
tion the same way the hydraulic brakes do on your tow
vehicle.
The hydraulic fluid from a master cylinder is used
to actuate the hydraulic wheel cylinder, which, in turn,
applies force against the brake shoes and drum. The main
differences between automotive hydraulic brakes and
hydraulic trailer brakes are the actuation systems that
transfer the braking signal from the tow vehicle to the
brake. A surge tongue actuator is required for a trailer with
hydraulic brakes. The hydraulic braking system must be
inspected by a dealer, at least as often as the brakes on
the tow vehicle, but no less than once per year. This
inspection includes an assessment of the condition and
proper operation of the wheel cylinders, brake shoes,
brake drums and hubs.
You must check the fluid level in the master cylinder reser-
voir at least every three months. If you tow your trailer an
average of 1,000 miles per month in a hot and dry environ-
ment, you must check the brake fluid level once a month.
The brake fluid reservoir is located on the tongue of the
trailer. Fill with DOT 3 or 4 brake fluid.
Brake Adjustment
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 used and
performance requires.
1. Jack up trailer and secure on adequate capacity
jack stands. check that the wheel and drum rotate
freely.
2. Because of the special stub axle arrangement,
adjustment cannot be made through the backing
plate. Remove the wheel and brake drum, and with
the starwheel on the adjuster assembly move the
brakes shoes outward. remount the brake drum and
wheel and rotate the wheel. Adjust until only a very
slight brake shoe drag is felt.
• Wheel Cylinders - Inspect for leaks and smooth opera-
tion. Clean with brake cleaner and flush with fresh
brake fluid. Hone or replace as necessary.
• Brake Lines - Check for cracks, kinks, or blockage.
Flush with fresh brake fluid. Bleed system to remove all
air. Replace as necessary.
• Shoes and linings - Inspect visually. Replace if the lin-
ing is worn (to within 1/16" or less), contaminated with
grease or brake fluid, or abnormally scored or gouged.
Replacement brake shoes part number 70131 (two
wheels).
• Hardware - Check all hardware. Check shoe retractor
spring, hold down springs, and adjuster springs for
stretch or wear. Replace as required.
• Drums - Check drums for scoring, cracking, or uneven
wear. Turn drum smooth only if under maximum diame-
ter. Replace as necessary.
Brake Actuator (Surge Tongue Actuator)
Bleeding Surge Brakes
Fill the Master Cylinder with DOT 3 or 4 brake fluid.
Bleed the brake system using a pressure-type brake
bleeder or manually, as follows:
1. Remove the two 5/16" x 1/2" Bolts and Lock Washers
that hold the Lever Guide, and the Flat Emergency
Lever Spring.
2. Remove the Lever Guide, and the Emergency Lever
Spring.
3. Using short strokes, pull forward on the Emergency
Lever, pumping the Master Cylinder until the brake
fluid within the Master Cylinder stops bubbling.
NOTE: Check the fluid level in the master cylinder frequently
while bleeding the brakes (every 4 or 5 strokes).
Refill as necessary to keep the level above half full.
4. When the bubbles stop close the valve.
5. Move to the next wheel and repeat steps 1 - 4.
6. Once bleeding is completed, refill the master cylin-
der and attach the cap securely.
7. Replace the emergency lever spring, the lever
guide, the lock washers and the hex head bolts.
8. Test the brakes by pulling the emergency lever for-
ward until it locks into the second notch position.
The lever should be approximately straight up.
BREAK-AWAY
CABLE
LEVER GUIDE
EMERGENCY LEVER
FILL
MASTER
CYLINDER
TONGUE MOUNTING
ADJUSTABLE COUPLER
MOUNTING CHANNEL