Air Brakes #2 Flashcards
One park brake fails to apply on a truck equipped with air brakes. The cause of this could be:
low air pressure.
both “a” and “b”.
leaking spring brake diaphragm.
broken spring in the chamber.
broken spring in the chamber.
When an automatic slack adjuster is set we would:
have to remove the slack adjuster to set it.
have greater travel than a manual slack adjuster when working properly.
have no travel because of self adjustment.
never need to be set.
have greater travel than a manual slack adjuster when working properly
Excessive oil and water are present in the air tanks when they are drained. Which of these could be the cause?
excess oil in the compressor crankcase.
reservoirs are not being drained often enough.
compressor air strainer is restricted.
all of the above.
all of the above.
When the treadle valve is in the applied position in a dual circuit brake system; the valves would be in the following position:
inlet open; exhaust open.
both valves closed.
inlet open; exhaust closed.
exhaust open; inlet closed.
inlet open; exhaust closed.
The pilot relay valve on the converter dolly relays:
service air pressure to the relay emergency valve on the dolly and the service line on the trailer.
supply air pressure to the relay emergency valve on the dolly.
supply air pressure to the relay emergency valve on the dolly and the service line on the trailer.
service air pressure to the relay emergency valve on the dolly.
service air pressure to the relay emergency valve on the dolly and the service line on the trailer.
The brake light switch is a normally:
closed switch that is opened by primary or secondary service pressure.
open switch that is closed by primary or secondary service pressure.
closed switch that is opened by primary or secondary reservoir pressure.
open switch that is closed by the primary or secondary reservoir pressure.
open switch that is closed by primary or secondary service pressure.
The purpose of the line at E is to: (figure 1)
apply the relay valve
prevent compounding
give a parking signal
give a service signal
prevent compounding
The function of valve B is to: (figure 1)
a) supply air to the trailer.
b) apply the park brakes on the tractor and trailer.
c) apply the park brakes on the trailer.
both (a) and (c) would be correct.
both (a) and (c) would be correct.
Referring to Figure 1, arrow “C” is pointing to:
a service brake relay valve.
a limiting quick release valve.
a tractor spring brake valve.
a quick release valve.
a tractor spring brake valve.
The valve at C would give us: (figuree)
modulated spring brake control with the loss of the primary circuit.
modulated spring brake control with the loss of the park/emergency circuit.
modulated spring brake control with the loss of the secondary circuit.
emergency application of the spring brakes with the loss of either service reservoir.
modulated spring brake control with the loss of the primary circuit.
The valve at C would give us: (figuree)
modulated spring brake control with the loss of the primary circuit.
modulated spring brake control with the loss of the park/emergency circuit.
modulated spring brake control with the loss of the secondary circuit.
emergency application of the spring brakes with the loss of either service reservoir.
modulated spring brake control with the loss of the primary circuit.
If reservoir H were to be damaged so it wouldn’t retain air what circuit would be lost (fig.1)
primary circuit.
trailer circuit.
park/emergency circuit.
secondary circuit.
primary circuit.
Referring to Figure 1, arrow “Z” is pointing to:
a emergency relay valve.
a service brake relay valve.
a tractor spring brake valve.
a tractor spring brake relay valve.
a tractor spring brake relay
valve.
If the line ruptured at J, the result would be: (figure 1)
loss of secondary service circuit.
park/emergency circuit would eventually apply.
loss of primary service circuit.
immediate application of tractor emergency brakes.
immediate application of tractor emergency brakes.
There is an air leak at point “X” in the piping shown in figure 1. Mechanic A says that this will cause the supply reservoir to leak down. Mechanic B says that this will cause the service reservoir to leak down. Who is correct?
neither A and B.
Mechanic B.
Mechanic A.
both A and B.
Mechanic A.
What reservoir is D? (figure 1)
supply reservoir.
primary service reservoir.
trailer supply reservoir.
secondary service reservoir.
secondary service reservoir.
The loss of reservoir G would result in: (figure 1)
the failure of the compressor.
immediate application of the emergency brakes on the tractor/trailer.
immediate application of emergency brakes on the tractor.
loss of either primary or secondary circuit as air is being used.
loss of either primary or secondary circuit as air is being used.
The function of valve F is: (figure 1)
a) apply tractor/trailer park brakes.
b) supply air to the trailer.
c) apply tractor park brakes.
both (a) and (c) are correct.
both (a) and (c) are correct.
From the figure 1 diagram identify valve A:
ABS modulator valve
limiting quick release valve
ABS quick release valve
ABS ratio valve
ABS modulator valve
If valve I leaks internally it could cause: (figure1)
a loss of primary air.
loss of park/emergency circuit.
application of the emergency brakes with the loss of both service reservoirs.
loss of secondary air.
application of the emergency brakes with the loss of both service reservoirs.
The function of the trailer supply line is to:
both are correct
fill the reservoirs on the trailer.
control the operation of the spring brakes.
both are correct
One safety precaution you must observe when parking a pre-CMVSS 121 trailer is:
the trailer wheels must be blocked.
the spring brakes must be caged.
the spring brakes must be applied.
the trailer reservoir must be drained.
the trailer wheels must be blocked.
When speaking of the dual braking system they are referring to:
air brake system with two separate service brake circuits.
air brakes on a tandem axle truck.
air brake system with a park/emergency circuit.
air brakes using both air disc and drum type brakes
air brake system with two separate service brake circuits.
The valves that are located in the compressor are:
inlet and exhaust.
exhaust and unloader.
inlet, unloader.
unloader, inlet and discharge.
unloader, inlet and discharge.
A driver has to move a truck that has the engine disabled and will not start. What has to be done to release the parking brakes to move the truck?
remove the axle shafts.
the brake chamber has to be disabled.
cage the spring brakes.
bleed air from the tanks.
cage the spring brakes.
Where does the governor sense the pressure in the air brake system?
supply tank.
compressor inlet.
service tank.
compressor outlet.
supply tank.
The purpose of the spring acting on the upper surface of the pilot relay valve piston is to:
hold the inlet valve open when the brakes are released.
increase application pressure.
reduce the time required to apply the trailer brakes.
reduce the time required to release the trailer brakes.
reduce the time required to apply the trailer brakes.
