PN 3006 EXAM 2 OBJECTIVE ASSESSMENT
TEST 2026 TEST BANK QUESTIONS AND
ANSWERS GRADED A+
⩥ In a B-train combination which of the following relay valves would
likely have the lowest crack pressure?!
The front tractor axle
The rear drive axle
The pup axle
The lead trailer axle.
Answer: The pup axle
⩥ Which of the following would be an output of the ECU (electronic
control unit) of an air brake ABS (anti-lock brake system)?!
The ABS indicator dash light
The exciter ring
The brake treadle valve
The speed sensor.
Answer: The ABS indicator dash light
⩥ Brake wear is uneven on only one side of the shoes. What should be
checked?!
,Anchor pins and bushings
Improper sized shoes
Worn S-cam bushings
ABS sensor out of adjustment.
Answer: Anchor pins and bushings
⩥ What is the desired air gap between the ABS wheel speed sensor and
the exciter ring?!
1/4" (6.25mm)
3/8" (9.5mm)
Air gap is not critical
As close as possible.
Answer: As close as possible
⩥ What is the proper position of hole(s) on air spring brake chambers?!
At a 90° angle
At a 30° angle
Facing downwards, toward the road
On the top, where it can be accessed.
Answer: Facing downwards, toward the road
⩥ What is the purpose of residual pressure in a hydraulic brake system
,To increase speed of a brake application
To inhibit moisture infiltrating the hydraulic system
To increase applied brake pressure
To decrease applied brake pressure.
Answer: To inhibit moisture infiltrating the hydraulic system
⩥ Air pressure is higher than normal. What is the most likely problem?!
Un-loader valve is stuck open
Defective governor circuit
Signal from supply tank
Air compressor is over capacity.
Answer: Defective governor circuit
⩥ What is an important requirement when selecting replacement S-
cams?!
Identify if a left or right hand S-cam is required
None, as all S-cams are identical
Check for S-cam roller lubrication
Test Rockwell hardness.
Answer: Identify if a left or right hand S-cam is required
, ⩥ What results when the dash-mounted trailer air supply valve (red) is
pulled outward (closed)?!
Air is directed through the tractor protection valve
The trailer air supply line is fully charged
The tractor parking brakes are applied
The trailer parking brakes are applied.
Answer: The trailer parking brakes are applied
⩥ When servicing an air dryer what also requires replacement?!
Purge valve
Heater element
Desiccant filter
Governor.
Answer: Desiccant filter
⩥ When the inversion valve of an air brake vehicle is in effect, what
does it modulate to slow the vehicle?!
Holds off pressure in the spring brake chamber
Directs air pressure to the service side of the dual chamber
Releases stored air pressure from a separate reservoir
Applies hydraulic pressure to the brakes.
Answer: Holds off pressure in the spring brake chamber
TEST 2026 TEST BANK QUESTIONS AND
ANSWERS GRADED A+
⩥ In a B-train combination which of the following relay valves would
likely have the lowest crack pressure?!
The front tractor axle
The rear drive axle
The pup axle
The lead trailer axle.
Answer: The pup axle
⩥ Which of the following would be an output of the ECU (electronic
control unit) of an air brake ABS (anti-lock brake system)?!
The ABS indicator dash light
The exciter ring
The brake treadle valve
The speed sensor.
Answer: The ABS indicator dash light
⩥ Brake wear is uneven on only one side of the shoes. What should be
checked?!
,Anchor pins and bushings
Improper sized shoes
Worn S-cam bushings
ABS sensor out of adjustment.
Answer: Anchor pins and bushings
⩥ What is the desired air gap between the ABS wheel speed sensor and
the exciter ring?!
1/4" (6.25mm)
3/8" (9.5mm)
Air gap is not critical
As close as possible.
Answer: As close as possible
⩥ What is the proper position of hole(s) on air spring brake chambers?!
At a 90° angle
At a 30° angle
Facing downwards, toward the road
On the top, where it can be accessed.
Answer: Facing downwards, toward the road
⩥ What is the purpose of residual pressure in a hydraulic brake system
,To increase speed of a brake application
To inhibit moisture infiltrating the hydraulic system
To increase applied brake pressure
To decrease applied brake pressure.
Answer: To inhibit moisture infiltrating the hydraulic system
⩥ Air pressure is higher than normal. What is the most likely problem?!
Un-loader valve is stuck open
Defective governor circuit
Signal from supply tank
Air compressor is over capacity.
Answer: Defective governor circuit
⩥ What is an important requirement when selecting replacement S-
cams?!
Identify if a left or right hand S-cam is required
None, as all S-cams are identical
Check for S-cam roller lubrication
Test Rockwell hardness.
Answer: Identify if a left or right hand S-cam is required
, ⩥ What results when the dash-mounted trailer air supply valve (red) is
pulled outward (closed)?!
Air is directed through the tractor protection valve
The trailer air supply line is fully charged
The tractor parking brakes are applied
The trailer parking brakes are applied.
Answer: The trailer parking brakes are applied
⩥ When servicing an air dryer what also requires replacement?!
Purge valve
Heater element
Desiccant filter
Governor.
Answer: Desiccant filter
⩥ When the inversion valve of an air brake vehicle is in effect, what
does it modulate to slow the vehicle?!
Holds off pressure in the spring brake chamber
Directs air pressure to the service side of the dual chamber
Releases stored air pressure from a separate reservoir
Applies hydraulic pressure to the brakes.
Answer: Holds off pressure in the spring brake chamber
