TABLE OF RECOMMENDED GRADE 5 OR HIGHER BOLT/NUT TORQUES
1-1/8”-7 UNC580-600 ft lbs.
1”-14 UNF530-550 ft lbs.
7/8”-14 UNF340-360 ft lbs.
¾”-16 UNF300-320 ft lbs.
5/8”-18 UNF120-140 ft lbs.
½”- 20 UNF60- 70 ft lbs.
3/8”- 16 UNF30- 40 ft lbs.
DISC WHEEL CAP NUTS–Single nut450-500 ft lbs.
DISC WHEEL CAP NUT INNER-Double nut450-500 ft lbs.
DISC WHEEL CAP NUT OUTER-Double nut450-500 ft lbs.
SPOKE WHEEL LUG NUTS200-250 ft lbs.
HUB CAP BOLTS12-16 ft lbs.
Anti-Lock Brake Systems (ABS) are required by current FMVSS 121 on all trailers over 10,000# GVWR The ABS controls the air pressure to the brake chambers by sensing the wheel rotation and feeding this back to the Electronic Control Unit (ECU) mounted on the service brake valve. This controlled pressure allows the brakes to apply at the level that keeps the wheels from locking up and losing control.
The primary requirement of a trailer ABS air brake system is clean dry air at the correct pressure. The air supplied by the tractor compressor is routed through the trailer ABS brake system, which activates the service and emergency braking. The system must be tight and leak free. The ABS air system should not have a pressure loss exceeding 4psi per minute, with the service brakes applied, at full pressure and the tractor engine off. This must be checked at the beginning of every trip. Always check the operation of the ABS brakes to be sure they work properly, before entering traffic.
Trailer axles (except dollies) are equipped with spring brake chambers. These operate the emergency and the parking brakes. DO NOT deactivate these chambers and DO NOT attempt to disassemble or open a spring brake chamber. An internal spring is in the chamber. It is extremely dangerous and could cause serious injury or death.
The glad-hand seals and hoses should be inspected for cracks, missing sections, damage or contamination. The hoses and tubing should not rub against any part of the tractor or trailer.
The trailer air reservoir should be drained of water and contamination daily. This is particularly important in wet, cold weather. As the reservoir is drained, the spring brakes will apply.
Check the brake system for cracked drums, bent chambers and push rods, loose chambers, out of adjusted brakes, loose or broken shoe springs, kinked or worn hoses and disconnected electrical harnesses. Do not operate the trailer if any defects are present.
If the ABS warning light goes on when first moving the trailer and stays on the ABS portion of the brake system is not working. The brakes will operate normally and should be checked by a service technician.