Lesson 3/Learning Event 1
The amount of braking action applied to the truck wheels depends on
how far down the brake pedal is depressed. When the pedal is pressed
way down, a greater amount of air pressure is applied to the brake
chambers. This causes the brake shoes and linings to press harder
against the brake drums, providing greater braking action.
FIGURE 19. BRAKE CHAMBER.
The brake chambers at each wheel convert air pressure to mechanical
motion. When air enters the air inlet, it moves the diaphragm which
moves the pushrod.