Dash Mounted Brake Controls
Note: See Chapter 11 Brake Systems, for additional information about brake systems.
Parking Brake Control Valve
The yellow diamond-shaped knob operates the parking brake valve. Pull the knob out to apply both the tractor and the trailer spring parking brakes. Push both the parking brake and the trailer air supply knobs in to release the tractor and trailer spring parking brakes. Before the spring parking brakes can be released, the air pressure in either air brake system must be at least 65 psi (447 kPa).
If the trailer is not equipped with spring parking brakes, pull the parking brake valve out to apply the tractor parking brakes and the trailer service brakes.
Trailer Air Supply Valve
The red octagonal-shaped knob operates the trailer air supply valve, which charges the trailer air supply system and releases the trailer spring parking brakes.
After the vehicle and its air hoses are connected to a trailer and the pressure in the air system is at least 65 psi (447 kPa), push the trailer air supply valve knob in (and leave it in) to charge the trailer air supply system and release the trailer spring parking brakes. Pull the trailer air supply valve out before disconnecting a trailer or when operating a vehicle without a trailer.
Trailer Brake Lever
The trailer brake lever is used to apply the trailer service brakes without applying the truck or tractor service brakes. It is usually mounted on the right-hand control panel. Move the lever down to apply the trailer brakes; move the lever up to release the trailer brakes. The lever automatically returns to the up position when it is released. The lever can be partially or fully applied, but in any partially on position it will be overridden by a full application of the service brake pedal.
Automatic Traction Control (ATC) Spin Switch
Notice: The ATC spin feature is intended to be used under specific slippery conditions that require momentary increased wheel spin. Using this option for an extended period of time may damage the vehicle brake system.
Pressing the ATC SPIN switch shown in Fig. shuts ATC off and allows drive wheel spin. Pressing the switch again, or cycling the ignition key, cycles the system back to normal operation.
