Page 13 - Driving Commercial Vehicles Manual

Trailer with spring parking brakes — service brake application ........... 167
Trailer with spring parking brakes — dynamited ................................. 168
Tractor protection ...................................................................................... 168
Trailer air supply valve .......................................................................... 169
Hand valve ............................................................................................ 169
Two-way check valve ............................................................................ 170
Bobtail tractors .......................................................................................... 170
Dual air tractor-trailer system — foot valve applied ................................. 171
Dual tractor-trailer system — primary air system failure ...................... 172
Dual tractor-trailer system — trailer breakaway ................................... 173
Other types of foundation brakes .............................................................. 173
Wedge brakes ....................................................................................... 174
Air disc brakes ....................................................................................... 174
Air-over-hydraulic brakes ...................................................................... 175
Other air brake system components ......................................................... 176
Air dryers ................................................................................................... 176
Alcohol evaporators and alcohol injectors ................................................ 177
Automatic drain valves .............................................................................. 178
Front wheel limiting systems ..................................................................... 178
Automatic front wheel limiting systems ............................................... 178
Manual front wheel limiting systems .................................................... 179
Spring parking brake emergency release system ..................................... 179
Pressure-protection valves ......................................................................... 180
Application pressure gauges ...................................................................... 180
Anti-lock braking systems ........................................................................... 180
Trailer ABS air brake systems ..................................................................... 182
Review questions .......................................................................................... 183

Chapter 9: air brake adjustment ................................................................. 185
What you’ll learn........................................................................................... 185
Brake adjustment — it’s critical ................................................................... 185
Brake adjustment — it’s the law ................................................................ 185
S-cam brake — released ............................................................................ 185
S-cam brake — applied .............................................................................. 186
S-cam brake — incorrectly adjusted and cold brake drum ....................... 186
S-cam brake — incorrectly adjusted and hot brake drum ......................... 187
Checking and adjusting s-cam brakes — manual slack adjuster ............. 187
Applied stroke method (service brake application) ................................... 188
Pry method of free stroke measurement ................................................... 188
Brake adjustment indicators ...................................................................... 189
Brake adjustment — manual slack adjuster ............................................... 189
Adjustment ................................................................................................. 190

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