HEAVY TRUCK BRAKES TEST
QUESTIONS & ANSWERS(RATED
A+)
When a truck has no air pressure in its tanks, which warning devices are activated
when the ignition key is turned on? - ANSWERA buzzer, a dash gauge and a red
light
What legislation mandates every required standard of a highway truck air brake
system? - ANSWERFMVSS 121
If a truck is FMVSS 121 compliant, which of the following air reservoirs must be
incorporated into the air brake circuit? - ANSWERSupply, primary and secondary
tanks
In a truck air brake system which sub circuit is primarily responsible for actuating
front axle service brakes when the system is functioning normally? -
ANSWERSecondary circuit
When a FMVSS 121 compliant tractor trailer combination is moving down the
highway at a speed of 50 mph, which circuit must be charged with air? -
ANSWERHold off circuit
What best describes the functions of a tractor protection valve? - ANSWERPressure
protects the tractor air supply in the event of loss of pressure in a trailer
Routes trailer supply air and service application signal to the trailer pneumatic
circuits
Blocks service signal air to the trailer until trailer air supply is activated
If you have yo make an adjustment to air system cut off pressure where should the
adjustment be made? - ANSWERThe governor
Technician A says that the relay section of a dual circuit foot valve is actuated
mechanically under normal operation. Technician B says that a primary piston of a
foot valve is actuated mechanically under normal operation. Who is correct? -
ANSWERTech B
Technician A says that a trailer service brake signal is always sourced from the
tractor primary circuit. Technician B says that a trailer service signal can only pass
through a tractor protection valve when it is in its ON state. Who is correct? -
ANSWERTech B
Technician A says that most current highway tractors use a 3-line TP valve.
Technician B says that a 2-line TP valve will remain OFF until the trailer air supply
dash button is depressed. Who is correct? - ANSWERTech B
QUESTIONS & ANSWERS(RATED
A+)
When a truck has no air pressure in its tanks, which warning devices are activated
when the ignition key is turned on? - ANSWERA buzzer, a dash gauge and a red
light
What legislation mandates every required standard of a highway truck air brake
system? - ANSWERFMVSS 121
If a truck is FMVSS 121 compliant, which of the following air reservoirs must be
incorporated into the air brake circuit? - ANSWERSupply, primary and secondary
tanks
In a truck air brake system which sub circuit is primarily responsible for actuating
front axle service brakes when the system is functioning normally? -
ANSWERSecondary circuit
When a FMVSS 121 compliant tractor trailer combination is moving down the
highway at a speed of 50 mph, which circuit must be charged with air? -
ANSWERHold off circuit
What best describes the functions of a tractor protection valve? - ANSWERPressure
protects the tractor air supply in the event of loss of pressure in a trailer
Routes trailer supply air and service application signal to the trailer pneumatic
circuits
Blocks service signal air to the trailer until trailer air supply is activated
If you have yo make an adjustment to air system cut off pressure where should the
adjustment be made? - ANSWERThe governor
Technician A says that the relay section of a dual circuit foot valve is actuated
mechanically under normal operation. Technician B says that a primary piston of a
foot valve is actuated mechanically under normal operation. Who is correct? -
ANSWERTech B
Technician A says that a trailer service brake signal is always sourced from the
tractor primary circuit. Technician B says that a trailer service signal can only pass
through a tractor protection valve when it is in its ON state. Who is correct? -
ANSWERTech B
Technician A says that most current highway tractors use a 3-line TP valve.
Technician B says that a 2-line TP valve will remain OFF until the trailer air supply
dash button is depressed. Who is correct? - ANSWERTech B
