AIR BRAKE SYSTEM TROUBLESHOOTING

1 QUALITY heavy duty PARTSPage 10 AIR BRAKE SYSTEM , 7:59 PM10 Page 11 QUALITY heavy duty PARTSAIR BRAKE SYSTEM , 7:59 PM11 QUALITY heavy duty PARTSPage 12 AIR BRAKE SYSTEM TROUBLESHOOTING1.) Before replacing any valve with a new or remanufactured valve, be sure to blow the air lines out eitherusing the vehicle s own air supply or shop air. Dirt is the greatest cause of premature air valve ) If pipe dope is used on fittings, use it sparingly. This can also get into the unit and cause a ) When installing fittings into a remanufactured valve, do not over tighten or it will crack the ) With the introduction of spring brakes, anti-compounding and 121 air BRAKE systems, because a valve isleaking air out of its exhaust, does not mean the valve is at fault. If a spring BRAKE is leaking from the thespring BRAKE to the service BRAKE side, that air will travel back up the service line and out the exhaust of thenext valve back.

2 Before replacing a valve that has air leaking from its exhaust, disconnect the delivery linesfrom that valve to determine if air is being fed back from some other valve or , TRACTORS and BUSES1.)Insufficient Brakes-Brakes need adjusting, lubricating or air pressure in the BRAKE SYSTEM (below 60psi).- BRAKE valve delivery pressure below size actuators and/or slack of part of a dual air remote mounted BRAKE valve, check ) Brakes Apply Too Slowly-Brakes need adjusting or air pressure in the BRAKE SYSTEM (below 60psi).-Insufficient BRAKE valve delivery leakage with brakes tubing or travel remote mounted BRAKE valve, check ) Brakes Release Too Slowly-Brakes need adjusting or valve not returning to fully tubing or port of BRAKE valve, quick release valve, orrelay valve restricted or BRAKE valve, quick release valve, or remote mounted BRAKE valve, check ) Brakes Do Not Apply-No air pressure in BRAKE or broken tubing or BRAKE remote mounted BRAKE valve, check ) Brakes Do Not Release- BRAKE rigging not in fully released BRAKE valve or relay or collapsed tubing or remote mounted BRAKE valve, check ) Brakes Grab or Erratic BRAKE -Grease on BRAKE lining = reline BRAKE valve or relay rigging vehicle load = high BRAKE )

3 Uneven Brakes-Brakes need adjusting, lubricating or axle on BRAKE lining - reline shoe return spring drum out of chamber diaphragm BRAKE slack adjuster or foundation BRAKE ) Air Pressure Will Not Rise To Normal-Faulty air gauge (registering incorrectly).-Excessive valve or fitting out of compressor drive supply ) Air Pressure Rise To Normal Too Slowly-Excessive valve or fitting reservoir compressor air speed too discharge valve or inlet drive belt slipping or faulty carbon in compressor cylinder head ordischarge ) Air Pressure Rises Above Normal-Faulty air gauge ( registering incorrectly).-Governor out of governor and safety in line between governor andcompressor or restricted unloading much clearance at compressor unloadervalves or compressor unloading mechanism stuckin closed )Air Pressure Drops Quickly WithEngine Stopped and Brakes Released-Leaking BRAKE tubing or discharge valves leakage elsewhere in the air BRAKE reservoir volume - high air ) Air Pressure Drops Quickly WithEngine Stopped and Brakes Fully Applied-Leaking BRAKE chamber, actuator, rotochamber orbrake left BRAKE tubing or hose water in reservoir ) Compressor Knocks Continously or Intermittently-Loose drive lash in drive gears or drive or burnt out carbon deposits in compressor )

4 Safety Valve Blows Off -Safety valve out of pressure in the air BRAKE SYSTEM above normaldue to faulty unloader mechanism or faulty ) Excessive Oil or Water in the BRAKE SYSTEM -Reservoirs not being drained oftern passing excessive air strainer engine oil pressure from engine oil (flooding) in compressor , 8:02 PM12 Page 13 QUALITY heavy duty PARTSAIR BRAKE SYSTEM TROUBLESHOOTING1.) Before replacing any valve with a new or remanufactured valve, be sure to blow the air lines out eitherusing the vehicle s own air supply or shop air. Dirt is the greatest cause of premature air valve ) If pipe dope is used on fittings, use it sparingly. This can also get into the unit and cause a ) When installing fittings into a remanufactured valve, do not over tighten or it will crack the ) With the introduction of spring brakes, anti-compounding and 121 air BRAKE systems, because a valve isleaking air out of its exhaust, does not mean the valve is at fault.

5 If a spring BRAKE is leaking from the thespring BRAKE to the service BRAKE side, that air will travel back up the service line and out the exhaust of thenext valve back. Before replacing a valve that has air leaking from its exhaust, disconnect the delivery linesfrom that valve to determine if air is being fed back from some other valve or ** The air BRAKE SYSTEM of a trailer isentirely dependent upon the air brakesystem of the towing vehicle for its airsupply and control. Therefore, the air airbrake SYSTEM of the towing vehicle mustbe in good condition; otherwise it will beimpossible to obtain a good brakeperformance on the trailer. Beforecondemning the air BRAKE SYSTEM on atrailer, always be sure the air brakesystem on the towing vehicle is function-ing properly. The following is based onon the assumption the tractor air brakesystem is functioning )Insufficient Brakes-Brakes need adjusting, lubricating or protection valve not in normal relay emergency trailer air supply - clogged emergency air pressure in the BRAKE SYSTEM (below 80psi).

6 - BRAKE valve delivery pressure in towing vehiclebelow tubing or size ) Brakes Apply Too Slowly-Brakes need adjusting or air pressure in the BRAKE SYSTEM (below 80psi).- BRAKE valve delivery pressure in towing vehiclebelow tubing, hose, or line leakage with brakes relay emergency ) Brakes Release Too Slowly-Brakes need adjusting or rigging port of relay emergency valve restricted tubing or ) Brakes Do Not Apply-Connecting hoses to trailer relay emergency protection valve not functioning properlyor not in normal position (see operating instruc-tions).-No air pressure in air BRAKE tubing or between tractor and trailer not ) Brakes Do Not Release-Connecting hoses to trailer valve on towing vehicle in applied rigging emergency valve in emergency relay emergency tubing or protection valve not functioning properlyor not placed in normal ) Brakes Grab-Grease on BRAKE lining - reline rigging relay emergency BRAKE valve on towing trailer )Uneven Brakes-Brakes need adjusting, lubricating or on BRAKE lining - reline shoe return spring drum out of BRAKE chamber or actuator tubing or slack adjuster or foundation BRAKE ) Excessive Leakage With Brakes Released-Relay emergency valve or drain valve tubing or uncoupled or leaking hose )

7 Excessive Leakage With Brakes Fully Applied-Faulty relay emergency BRAKE chamber tubing or uncoupled or leaking hose ) Excessive Leakage with RelayEmergency Valve in Emergency Position-Faulty relay emergency ) Excessive Oil and Water Present in the Air BRAKE not drained often , 8:02 PM13 QUALITY heavy duty PARTSPage 14 AIR BRAKE SYSTEM TROUBLESHOOTINGPROBLEMCAUSEREMEDY1) Dryer is constantly cyclingor Excessive SYSTEM Defective Defective one way valve between air dryer and wet Kinked or plugged discharge Repair air Check governor for proper cut-in, cut-out pressure and excessive leakage. Repair or replace Check to see if air is passing through check Check to see if air passes through discharge line. Check for kinks, bends, excessive carbon deposits.

8 Clean or replace discharge ) Water and sludge appear in wet Plugged desiccant cartridge or Improper length or material of discharge Restricted purge No purge Compressor passing excessive Replace dessicant cartridge Use minimum of six-foot tubing for two- cylinder compressor; ten-foot for one cylinder compresssor. Flex hose can be substituted at a ratio of 1- 1/2 of flex hose for each 1 of Clean orfice with small drill bit or See cause and remedy for problem # Check for proper compressor installation. Replace compressor if ) Safety valve on air dryer opens during Plugged or saturated desiccant cartridge or Defective one way check Restricted discharge See remedy 2E, replace desiccant cartridge/ Check to see if air is passing through check valve.

9 Repair or replace check Clean or replace air discharge ) Constant leak of air from purge Purge control line connected to reservoir or exhaust port of Inlet and outlet air connections Purge valve frozen Restricted discharge Faulty Purge control line must be connected to unloader port of Compressor discharge line must be connected to dryer inlet Repair or replace Check to see if air passes through discharge line. Check for kinks, bends or excessive carbon Check governor for proper cut-in, cut-out pressure and excessive leakage. Repair or replace ) Air dryer does not purge or exhaust Line between governor and dryer kinked, plugged, broken or Faulty heater or Faulty purge Check to make sure air flows through purge control line when compressor is unloaded.

10 Clean or replace purge control Repair or replace After determining air reaches purge valve, repair purge ) Slow air pressure build Restricted Plugged desiccant or Check to see if air passes through discharge line. Check for kinks, bends or excessive carbon deposits. Clean or replace discharge Replace desiccant ) Heater Broken wire or bad Blown Defective Repair or replace wiring to Check fuse and replace if Repair or replace , 8:02 PM14