An air supply control in its "emergency" position will:

Question

Tractor protection controls in older vehicles may be operated by levers instead of knobs. If an air supply control is set in its "emergency" position, the air supply will be stopped and the trailer emergency brakes will be applied.

Accepted Answer

Apply the trailer emergency brakes.

Answer

Turn on the air supply.

Answer

Prevent a skid.

Answer

Accelerate the vehicle.