AIR BRAKES - GENERAL INFORMATION DIAGNOSIS GUIDES (Cont ’d.) CONDITION POSSIBLE CAUSE RESOLUTION Brakes Grab or Erratic Braking Grease on brake lining Reline brakes Faulty brake valve or relay valve Repair or replace as necessary Sticking shoe guide pins Repair or replace as necessary Sticking anchor pins Repair or replace as necessary Broken or weak return springs Repair or replace as necessary High brake pressure Check air supply and delivery systems No vehicle load Operate vehicle with caution when not under load Loose drum or brake mounting Re-torque fasteners Uneven Brakes Brakes need adjusting or relining Adjust or reline as necessary Improper axle mounting Check and repair as necessary Grease on brake lining Reline brakes Brake shoe return spring broken Replace as necessary Brake drum out of round Refinish drum if possible without exceeding maximum diameter, or replace as necessary Brake chamber diaphragm failure Repair or replace as necessary Wrong or mixed brake lining Replace as necessary Broken foundation brake parts Repair or replace as necessary Air Pressure Will Not Rise to Faulty air gauge (registering Repair or replace as necessary Normal incorrectly) Excessive valve or fitting leakage Check all valves and connections Repair or replace as necessary Governor out of adjustment Adjust or replace as necessary Slipping compressor drive belt Tighten or replace belt as necessary Broken supply line Replace as necessary Faulty compressor Repair or replace as necessary Air Pressure Rises to Normal Excessive valve or fitting leakage Check all valves and connections Too Slowly Repair or replace as necessary Clogged compressor air strainer Repair or replace as necessary Engine speed too slow Adjust or regulate as necessary Compressor discharge valve or Repair or replace as necessary inlet valves leaking Compressor drive belt slipping or Repair or replace as necessary faulty drive coupling Worn compressor Repair or replace as necessary Excessive carbon in compressor Repair or replace as necessary cylinder head or discharge line CTS-4154Y - Page 24