Operating the Brakes
To ensure safe operation and minimum brake wear, follow the steps below when operating the brakes.
- When the ignition switch is turned on, the low air pressure
warning light (pressure circle icon) illuminates and the emergency
buzzer sounds.
- Monitor the air pressure system by observing the low air pressure warning light, the emergency buzzer, and both the primary and secondary air pressure gauges.
- The warning light and buzzer shut off when air pressure in both systems reaches 65 to 75 psi (448 to 517 kPa).
- Before driving the vehicle, continue to monitor the air pressure system until the air compressor has built up a minimum pressure of 95 psi (655 kPa) in both the primary and secondary air systems.
- While driving, the low air pressure warning light and buzzer
come on if air pressure drops below 65 to 75 psi (448 to 517 kPa)
in either system.
- If this happens, check the air system pressure gauges to determine which system has low air pressure.
- Although vehicle speed can be reduced using the service brake, either the front or rear service brakes will not be operating, causing a longer stopping distance.
- Bring the vehicle to a safe stop and have the air system repaired before continuing.
- During normal brake stops, depress the service brake 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, shift the transmission to neutral. Apply the parking brakes, if the vehicle is to be parked.
Important: In the event of a total loss of service brakes, use the parking brake control valve to bring the vehicle to a complete stop in the safest location possible.
Notice: 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.
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.