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This chapter includes inspection checklists, charts and circuit diagrams that will help you complete the inspections you need to make, as well as help you prepare for the Ministry of Transportation air brake endorsement practical examination.
The Seven-Step Air Brake check is designed to test the governor cut-in and cut-out pressures, air pressure leakage, warning buzzer, brake valves and air pressure rebuild rates. Brakes off means the yellow and/or red valve is pushed in (on = valve out).
Usually driven by the vehicle engine, the air compr essor builds the air pressure for the air brake system. The air compressor is typically cooled by the engine coolant system and lubricated by the engine oil sup ply. (Certain models have self-lubricated and/or air-coo led versions available.)
Most large commercial vehicles are equipped with an air brake system. You must have an air brake endorsement on your driver’s licence to drive these vehicles. The purpose of this handbook is to introduce you to the knowledge and skills you need to drive a vehicle with air brakes in a safe and lawful manner.
Air brake system means a system that uses air as a medium for transmitting pressure or force from the driver control to the service brake, including an air-over-hydraulic brake
-Low air pressure in the brake system (below 60 psi).-Brake valve delivery pressure below normal.-Wrong size actuators and/or slack adjusters.-Failure of part of a dual air system.-If remote mounted brake valve, check linkage. 2.) Brakes Apply Too Slowly-Brakes need adjusting or lubricating.-Low air pressure in the brake system (below 60 psi).
Air pressure is usually measured in kiloPascals (kPa) or pounds per square inch (psi). The normal pressure range of an air brake system is determined by the points where the air compressor is turned on (cut-in pressure) and turned off (cut-out pressure).
