HEAVY TRUCK BRAKES FINAL PAPER QUESTIONS AND
ANSWERS 2025/2026
✔✔When secondary circuit signal air is routed to through the trailer service signal
circuit, which brake valve is responsible? - ✔✔Trailer hand valve
✔✔Technician A says that the tractor secondary circuit is actuated by the relay piston in
a treadle valve. Technician B says that when a treadle valve is functioning properly, the
relay piston is actuated pneumatically. Who is correct? - ✔✔Both techs
✔✔What is the reason for using different relay valve crack pressure in a tractor trailer
semi combination? - ✔✔Balance the braking on the tractor and the trailer
✔✔What is the function of the quick release valve in the hold off circuit? -
✔✔Accelerates parking brake application
✔✔What is a good way of describing the parking brake circuit? - ✔✔Emergency circuit
✔✔Technician A says that the only means of stopping an air brake equipped, semi
trailer combination is by actuating the service application circuit. Technician B says that
unless the hold off circuit is fully charged with air a semi combination rig can opt be
moved. Who is correct? - ✔✔Tech B
✔✔What amount of braking force is a spring brake chamber capable of delivering? -
✔✔About that of a full service application
✔✔Technician A says that an inversion valve only plays a role when a rig has suffered a
significant loss of air. Technician B says that the inversion valve acts as an accumulator
to provide additional air for emergency braking. Who was correct? - ✔✔Tech A
✔✔Technician A says that the steering column mounted hand control valve actuated
the tractor service brakes without applying the trailer brakes. Technician B says that the
hand control valves sources its air from the tractor secondary circuit. Who is correct? -
✔✔Tech B
✔✔ When a truck has no air pressure in its tanks, which warning devices are activated
when the ignition key is turned on? - ✔✔A buzzer, a dash gauge and a red light
✔✔What legislation mandates every required standard of a highway truck air brake
system? - ✔✔FMVSS 121
✔✔If a truck is FMVSS 121 compliant, which of the following air reservoirs must be
incorporated into the air brake circuit? - ✔✔Supply, primary and secondary tanks
ANSWERS 2025/2026
✔✔When secondary circuit signal air is routed to through the trailer service signal
circuit, which brake valve is responsible? - ✔✔Trailer hand valve
✔✔Technician A says that the tractor secondary circuit is actuated by the relay piston in
a treadle valve. Technician B says that when a treadle valve is functioning properly, the
relay piston is actuated pneumatically. Who is correct? - ✔✔Both techs
✔✔What is the reason for using different relay valve crack pressure in a tractor trailer
semi combination? - ✔✔Balance the braking on the tractor and the trailer
✔✔What is the function of the quick release valve in the hold off circuit? -
✔✔Accelerates parking brake application
✔✔What is a good way of describing the parking brake circuit? - ✔✔Emergency circuit
✔✔Technician A says that the only means of stopping an air brake equipped, semi
trailer combination is by actuating the service application circuit. Technician B says that
unless the hold off circuit is fully charged with air a semi combination rig can opt be
moved. Who is correct? - ✔✔Tech B
✔✔What amount of braking force is a spring brake chamber capable of delivering? -
✔✔About that of a full service application
✔✔Technician A says that an inversion valve only plays a role when a rig has suffered a
significant loss of air. Technician B says that the inversion valve acts as an accumulator
to provide additional air for emergency braking. Who was correct? - ✔✔Tech A
✔✔Technician A says that the steering column mounted hand control valve actuated
the tractor service brakes without applying the trailer brakes. Technician B says that the
hand control valves sources its air from the tractor secondary circuit. Who is correct? -
✔✔Tech B
✔✔ When a truck has no air pressure in its tanks, which warning devices are activated
when the ignition key is turned on? - ✔✔A buzzer, a dash gauge and a red light
✔✔What legislation mandates every required standard of a highway truck air brake
system? - ✔✔FMVSS 121
✔✔If a truck is FMVSS 121 compliant, which of the following air reservoirs must be
incorporated into the air brake circuit? - ✔✔Supply, primary and secondary tanks
