Brake Systems (Ch. 28) - DTC 1
What is the potential energy of an air brake system? (pg. 886) - ANS-Compressed air
When a truck has no air pressure in its tanks, what warning devices are activated when
the ignition key is turned on? (pg. 888) - ANS-A buzzer, Red light, dash gauge
When a properly functioning treadle valve is actuated by foot pressure, what will
determine what pressure is metered out to actuate the primary and secondary service
circuits? (pg. 889) - ANS-Mechanical force applied to the treadle
What governor cut-out pressure is recommended by the ATA (American Trucking
Association) TMC (Technical and Maintenance Council) for highway trucks? (pg. 894) -
ANS-125 psi
If you have to make an adjustment to air system cut-out pressure, where should the
adjustment be made? (pg. 895) - ANS-Governor
What pressure values are FMVSS-121 compliant for governor cut-out and cut-in
pressures? (pg. 895) - ANS-Cut-out at 125 psi and Cut-in at 100 psi
What term is often used to describe a truck safety pressure relief valve? (pg. 898) -
ANS-Pop-off valve
What pressure is a pop-off valve set to trip at in most highway truck applications? (pg.
898) - ANS-150 psi
In a truck air brake system, which sub-circuit is primarily responsible for actuating front
axle service brakes when the system is functioning normally? (pg. 901) -
ANS-Secondary Circuit
What is the primary function of a relay valve? (pg. 901) - ANS-Remote-controlled
service brake valve
An air brake equipped highway tractor features single dash air pressure gauge with two
needles, one green and the other red. What does the red needle display? (pg. 902) -
ANS-Secondary circuit pressure
What is the potential energy of an air brake system? (pg. 886) - ANS-Compressed air
When a truck has no air pressure in its tanks, what warning devices are activated when
the ignition key is turned on? (pg. 888) - ANS-A buzzer, Red light, dash gauge
When a properly functioning treadle valve is actuated by foot pressure, what will
determine what pressure is metered out to actuate the primary and secondary service
circuits? (pg. 889) - ANS-Mechanical force applied to the treadle
What governor cut-out pressure is recommended by the ATA (American Trucking
Association) TMC (Technical and Maintenance Council) for highway trucks? (pg. 894) -
ANS-125 psi
If you have to make an adjustment to air system cut-out pressure, where should the
adjustment be made? (pg. 895) - ANS-Governor
What pressure values are FMVSS-121 compliant for governor cut-out and cut-in
pressures? (pg. 895) - ANS-Cut-out at 125 psi and Cut-in at 100 psi
What term is often used to describe a truck safety pressure relief valve? (pg. 898) -
ANS-Pop-off valve
What pressure is a pop-off valve set to trip at in most highway truck applications? (pg.
898) - ANS-150 psi
In a truck air brake system, which sub-circuit is primarily responsible for actuating front
axle service brakes when the system is functioning normally? (pg. 901) -
ANS-Secondary Circuit
What is the primary function of a relay valve? (pg. 901) - ANS-Remote-controlled
service brake valve
An air brake equipped highway tractor features single dash air pressure gauge with two
needles, one green and the other red. What does the red needle display? (pg. 902) -
ANS-Secondary circuit pressure
