Document zz1Xpg5aO015rRrpY4Qd4NBQ7

J)ex CORPORATION AMERICAN BRAKEBLOK DIVISION HEAVY DUTY SERVICE BULLETIN BULLETIN NO. 20 TROUBLE SHOOTING CHECK LIST FOR TRAILERS When problems arise with the trailer brakes, first be certain that the tractor brakes are functioning properly and accepting their share of the braking of the entire train. Since the actuation of the trailer brakes is entirely dependent on the air brake system of the tractor, it is important that their association be compatible -in that the systems be synchronized. We refer you to our handout on the "Procedure for Check-Out of Air Brake Systems" as a follow through. Tractor and trailer brakes have much in common and complaints similar in nature frequently have corrections applicable to both. However, both have some com ponents that are individual to either the tractor or trailer. Our Bulletin No. 19 can provide supplemental information that may be of help in some instances where the corrections are common to both and are not covered in this bulletin. Driver Complaints Causes Insufficient Brakes Brakes need adjusting, lubricating, or relining. Tractor protection valve not in "normal" position. Faulty relay emergency valve. No trailer air supply-clogged emergency line. Low air pressure in air brake system (below 80 psi) Brake valve delivery pressure in towing vehicle below normal. Restricted tubing or hose. Wrong size actuators. Brakes Apply Too Slowly . Brakes need adjusting or lubricating. Low air pressure in the air brake system (below 80 psi). Brake valve delivery pressure in towing vehicle below normal. Restricted tubing, hose or line filter. Excessive leakage with brakes applied. - Faulty relay emergency valve. SPNY 005997 SCF-ABEX-0022 -Lt- . _.I----C_^,. ------ ., .tv,, BULLETIN NO. 20 Driver Complaints Brakes Release Too Slowly Page 2 Causes Brakes need adjusting or lubricating. Brake rigging binding. Exhaust port of relay emergency valve restricted or plugged. Restricted tubing or hose. Brakes Do Not Apply Connecting hoses,to trailer crossed. Faulty relay emergency valve. Tractor protection valve not functioning properly or not in normal position (see operating instructions). No air pressure in air brake system. Restricted tubing or hose. Hoses between tractor and trailer not connected.' Brakes Do Not Release Connecting hoses to trailer crossed. * Brake valve on towing vehicle in applied position. - Brake rigging binding. Relay emergency valve in emergency position. Faulty relay emergency valve. Restricted tubing or hose. Tractor protection valve not functioning properly or not placed in "normal" position. Brakes "Grab" Grease on brake lining -- reline brakes. Brake rigging binding. Faulty relay emergency valve. Faulty brake valve on towing vehicle. No trailer load..-'I;. Uneven Brakes 4rSvi - ' ~v-. ***- - . * *) Excessive Leakage with Brakes Released Excessive Leakage with. Brakes Fully Applied' _ Brakes need adjusting, lubricating or relining.1 Grease on brake: lining. . Brake shoe return spring- broken. Brake drum out of; round. .' Leaking brake chamber or actuator diaphragm. - - Restricted-tubing; or-, hose. " Broken slack adjuster or foundation brake parts. v- c ^ * . Relay emergency valve or drain valve leaking. .. Leaking tubing or Hose. Hose uncoupled or' leaking hose coupling. . - ** Faulty relay emergency valve. Leaking brake chamber diaphragm. Leaking tubing or hose. Hose uncoupled orgleaking hose coupling. * <. SPNY 005998 bulletin no. 20 Driver Complaints Excessive Leakage with Relay Emergency Valve in Emergency Position Inspection Disclosures Excessive Oil and Water Present in the Air Brake System Mechanic's Complaints Drums Won't Go On Page 3 Causes Faulty relay emergency valve. Causes Reservoirs not drained often enough. Compressor passing excessive oil. Compressor air strainer restricted. * Excessive engine oil pressure. . Back pressure from engine crankcase. - , Excessive oil (flooding) in compressor crankcasev Causes Tapered blocks incorrectly positioned. Undersize brake drum. Oversize rollers or cam plates. Shoes not retracted fully. Incorrect thickness lining. Distorted brake shoe. Rusty or dirty shoe table. Wrong brake shoe. PJM/pn Patrick J. Meade Technical Service Engineer' ~ SPNY 005999