When a truck has no air pressure in its tanks, which warning devices are activated when the ignition key
is turned on? - ANS_A buzzer, a dash gauge and a red light
What legislation mandates every required standard of a highway truck air brake system? - ANS_FMVSS
121
If a truck is FMVSS 121 compliant, which of the following air reservoirs must be incorporated into the air
brake circuit? - ANS_Supply, 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? - ANS_Secondary 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? - ANS_Hold off circuit
What best describes the functions of a tractor protection valve? - ANS_Pressure 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? - ANS_The governor
, How is the relay section of an FMVSS 121 compliant duel circuit foot valve activated when the air brake
is functioning properly? - ANS_Pneumatically
What is the function of a quick release gladhand when used? - ANS_Speeds service brake release timing
What best accounts for brake feel in an air brake system? - ANS_Resistance of application pressure
versus for pressure
What is the potential energy of an air brake system? - ANS_Compressed air
When a tractor spring brake assembly is charged with air on both its service and hold off chambers what
results is known as? - ANS_Compounding
What is true about hold off pressure in current truck and trailer air brake systems? - ANS_Its regulated
at 90 psi.
What is the minimum compressed air reservoir volume dedicated to the air brakes required by an
FMVSS 121 compliant highway trailer? - ANS_8 times total brake chamber volume
What term is used to describe a truck safety pressure relief valve? - ANS_Pop off valve
What pressure is a pop off valve set to trip at in most highway truck applications? - ANS_150 psi.
When an inversion valve is activated, what happens? - ANS_Some hold off air is exhausted
When a properly functioning treadle valve is actuated by foot pressure, which of the following will
determine what pressure is metered out to actuate the primary and secondary service circuits?
A. Mechanical force is applied to the treadle
is turned on? - ANS_A buzzer, a dash gauge and a red light
What legislation mandates every required standard of a highway truck air brake system? - ANS_FMVSS
121
If a truck is FMVSS 121 compliant, which of the following air reservoirs must be incorporated into the air
brake circuit? - ANS_Supply, 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? - ANS_Secondary 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? - ANS_Hold off circuit
What best describes the functions of a tractor protection valve? - ANS_Pressure 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? - ANS_The governor
, How is the relay section of an FMVSS 121 compliant duel circuit foot valve activated when the air brake
is functioning properly? - ANS_Pneumatically
What is the function of a quick release gladhand when used? - ANS_Speeds service brake release timing
What best accounts for brake feel in an air brake system? - ANS_Resistance of application pressure
versus for pressure
What is the potential energy of an air brake system? - ANS_Compressed air
When a tractor spring brake assembly is charged with air on both its service and hold off chambers what
results is known as? - ANS_Compounding
What is true about hold off pressure in current truck and trailer air brake systems? - ANS_Its regulated
at 90 psi.
What is the minimum compressed air reservoir volume dedicated to the air brakes required by an
FMVSS 121 compliant highway trailer? - ANS_8 times total brake chamber volume
What term is used to describe a truck safety pressure relief valve? - ANS_Pop off valve
What pressure is a pop off valve set to trip at in most highway truck applications? - ANS_150 psi.
When an inversion valve is activated, what happens? - ANS_Some hold off air is exhausted
When a properly functioning treadle valve is actuated by foot pressure, which of the following will
determine what pressure is metered out to actuate the primary and secondary service circuits?
A. Mechanical force is applied to the treadle
