All vehicles equipped with air brakes must have
- an application pressure gauge.
- a tank pressure gauge. ✓
- a hydraulic system as a backup.
- at least one brake heater.
Answer: B. a tank pressure gauge.
All vehicles equipped with air brakes must have a tank pressure gauge.
Why this is the answer
The handbook says that on vehicles with air brakes, the air-pressure gauge should show sufficient pressure before you move, and the audible warning must have stopped or the warning light must be off. That gauge is the tank pressure gauge used to check the air supply. The passages do not require an application pressure gauge, a hydraulic backup, or a brake heater.
Why the other answers are wrong
- A. an application pressure gauge. — An application pressure gauge is not required by the passages; they refer to checking the air-pressure gauge before moving.
- C. a hydraulic system as a backup. — A hydraulic system as a backup is not mentioned, and the passages treat air brakes as an air-pressure system with spring brakes.
- D. at least one brake heater. — At least one brake heater is not mentioned anywhere in the passages as a required item.
Remember it
Air brake check: gauge up, buzzer off.
Official handbook: Official MTO Truck Handbook, Starting the engine