Air Brake Manual

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SECTION TWO - THE COMPONENTS OF AN AIR BRAKE SYSTEM 11
Section One of this manual has explained that it is possible to gain a mechanical advantage through the use of levers and that air under pressure can be used to gain a mechanical advantage. Section Two will explain how air under pressure can be used to operate the air brakes of a vehicle. Piping illustrations have been kept simple in order to be easily understood. The piping arrangements found on vehicles in actual use on the highway might differ somewhat from the illustrations in this manual. The Components of an Air Brake System A basic air brake system capable of stopping a vehicle has five main components: 1. A compressor to pump air with a governor to control it. 2. A reservoir or tank to store the compressed air. 3. A foot valve to regulate the flow of compressed air from the reservoir when it is needed for braking. 4. Brake chambers and slack adjusters to transfer the force exerted by the compressed air to mechanical linkages. 5. Brake linings and drums or rotors to create the friction required to stop the wheels. It is necessary to understand how each of these components work before studying their functions in the air brake system. Governor Compressor and Governor Compressed air is used to transmit force in an air brake system. The source of the compressed air is a compressor (1). A compressor is designed to pump air into a reservoir which results in pressurized air. The compressor is driven by the vehicle’s engine, either by belts and pulleys or shafts and gears. In vehicles where the compressor is driven by belts, they should be checked regularly for cracks and tension. Also, check the compressor for broken mounting brackets or loose bolts. The compressor is in constant drive with the engine. Whenever the engine is running, so is the compressor. When pressure in the system is adequate, anywhere from a low of 80 psi to a high of 135 psi it is not necessary for the compressor to pump air. A governor (2) controls the minimum and maximum air pressure in the system by controlling when the compressor pumps air. This is known as the “loading” or “unloading” stage. Most compressors have two cylinders similar to an engine’s cylinders. When the system pressure reaches its maximum, which is between 115 and 135 psi, the governor places the compressor in the “unloading” stage. The compressor must be able to build reservoir air pressure from 50 to 90 psi within three minutes. If unable to do so the compressor requires servicing. A compressor may not be able to build air pressure from 50 to 90 psi within three minutes if the air filter is plugged or if the belt is slipping. If these were not at fault the compressor could be faulty. Pressure setting spring Exhaust port Exhaust port Unload port Unload port Reservoir port Reservoir port 12
Page 1 and 2: Air Brake Manual PUBLIC SAFETY Ce d
Page 3 and 4: Safety Tips 1. Reminder - is your c
Page 6 and 7: SECTION ONE - BRAKES AND BRAKING 5
Page 8 and 9: Speed-weight-distance The distance
Page 10: said that brake lag is the time it
Page 15 and 16: · Compression stroke: The upward m
Page 17 and 18: Safety Valve A safety valve (4) pro
Page 19 and 20: Air inlet Previously illustrated ar
Page 21 and 22: Brake lining material is attached t
Page 23 and 24: Air-actuated Hydraulic Brake System
Page 25 and 26: Section Summary Questions 1. What a
Page 27 and 28: Basic Air Brake System Air is pumpe
Page 29 and 30: Quick Release Valve The application
Page 31 and 32: Tandem Rear Axles 34 33 13 The air
Page 33 and 34: Spring Parking Brake Systems (Singl
Page 35 and 36: Closing the control valve shuts off
Page 38 and 39: SECTION FIVE - TRAILER SYSTEM 37
Page 40 and 41: Application Line “T” 13 20 31 T
Page 42 and 43: Hand Valve Application 30 26 31 In
Page 44 and 45: Tractor Protection System (closed)
Page 46 and 47: 30 28 26 24 20 31 In this illustrat
Page 48 and 49: Charging the Trailer System 28 24 3
Page 50 and 51: If a trailer that is not equipped w
Page 52 and 53: Loss of Reservoir Air Pressure 28 2
Page 54 and 55: SECTION SIX - DUAL AIR BRAKE SYSTEM
Page 56 and 57: Dual Air Brake System 29 31 1 4 5 7
Page 58 and 59: Spring Parking Brakes with Modulato
Page 60: Section Summary Questions 1. What i
Page 63 and 64:
Axle Anti-lock Brake System (ABS) A
Page 65 and 66:
Automatic Traction Control (ATC) Au
Page 67 and 68:
Brake Adjustment On vehicles equipp
Page 69 and 70:
S-cam Brake Adjustment with Manual
Page 71 and 72:
· there are no air leaks; · the g
Page 73 and 74:
Single Unit (Not for air over hydra
Page 75 and 76:
· At 90 psi or above, release the
Page 77 and 78:
Compressor and Warning Devices Chec
Page 79 and 80:
METRIC CONVERTER mph MAXIMUM MAXIMU
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Air Brake Manual

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