Page 12 - Driving Commercial Vehicles Manual

Basic air brake components ....................................................................... 142
Force multipliers ........................................................................................... 143
Air brake chamber components ................................................................. 143
Leverage and air pressure ......................................................................... 144
Long stroke and regular stroke brake chambers ....................................... 144
Air brake chamber — air pressure applied ............................................... 144
Foundation brakes: s-cam type ................................................................. 145
Compressor .................................................................................................. 146
Intake stroke .............................................................................................. 147
Compression stroke .................................................................................... 148
Governor ....................................................................................................... 148
Reservoirs ...................................................................................................... 149
Foot valve ..................................................................................................... 149
How air brakes work ................................................................................... 150
Brakes applied ............................................................................................ 150
Brakes released .......................................................................................... 151
Dual air brake systems ................................................................................. 151
Components of a dual air brake system ................................................... 152
Supply, primary and secondary reservoirs ................................................. 152
One-way check valve ................................................................................. 152
Reservoir pressure gauges ........................................................................ 153
Low-air warning device ............................................................................. 153
Quick release valve .................................................................................... 154
Relay valve ................................................................................................. 155
Dual system with primary system failure .................................................. 156
Parking brakes ............................................................................................. 156
Spring parking brakes ................................................................................. 157
Applying and releasing spring parking brakes ......................................... 158
Spring parking brake — released ........................................................ 158
Spring parking brake — service brake applied ................................... 159
Spring parking brake — spring brake applied .................................... 160
Driver alert — compounding of brakes .................................................... 160
Spring parking brake — manual release .............................................. 160
Spring parking brakes in dual air brake systems ....................................... 161
Blended air ........................................................................................... 162
Dual air brake system — partial system failure ..................................... 162
Safety actuator parking brakes .................................................................. 163
Tractor-trailer air brake systems ................................................................. 164
Trailer with relay emergency valve — charging ................................... 165
Trailer with relay emergency valve — applying ................................... 165
Trailer with relay emergency valve — dynamited ................................ 166
Trailer with spring parking brakes — charging .................................... 166

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