Brakes NOTE: Before a vehicle with insufficient system air pressure can be moved, the spring parking brakes must be released by applying an external air source at the gladhands, or by manually caging (manually releasing) the parking brake springs. After correcting the brake system problem, uncage the spring parking brakes before resuming normal vehicle operation. f421624 Fig. 7.1, Parking Brake Valve Knob Operation CAUTION Before driving the vehicle, secure all loose items in the cab so that they will not fly forward during a full brake application. Make sure all occupants are wearing seat belts.
Do not use the spring parking brakes if the service brakes are hot, such as after descending a steep grade. Also, do not use the spring parking brakes during freezing temperatures if the service brakes are wet. To do so could damage the brakes if hot, or cause them to freeze during cold weather. During normal brake stops, depress the foot brake con- trol pedal until braking action slows down the vehicle. Increase or decrease the pressure on the pedal so that the vehicle comes to a smooth, safe stop. When the forward speed of the vehicle has decreased almost to the idling speed of the engine, push the clutch pedal in, and shift the transmission into neutral.
Apply the spring parking brakes if the vehicle is to be parked. If the brakes are wet, drive the vehicle in low gear and lightly apply the brakes to heat and dry them. Allow hot brakes to cool before using the spring parking brakes. Always chock the tires. The yellow diamond-shaped knob ( Fig. 7.1 ) on the con- trol panel actuates the parking brake valve. Pulling out the knob applies the spring parking brakes. If the brakes are wet, drive the vehicle in low gear and lightly apply the brakes to heat and dry them. Allow hot brakes to cool before using the spring parking brakes. Always chock the tires. 7.2