Final Test Brakes/51 Questions
and Answers
When you are installing open ancho brake shoes (such as Q-brakes) which of
the following steps should be performed first? - - install the upper brake
shoe
- Technician A says that in the event of a total failure of the primly circuit in
an FMVSS-121 compliant tractor-trailer combination, the rig can be brought
safely to a complete stop.
Technician B says that in the event of a total failure of the primary circuit the
relay section of the treadle calve will be actuated mechanically. Who is
correct? - - Both Technician A and B
- How many degrees of tire rotation does each tooth in a 100-tooth ABS
reluctor wheel represent? - - 3.6- degrees
- A system air pressure loss occurs on a trailer resulting in a gradual
pressure bleed down. Which of the following will occur first? - - spring brakes
on trailer begin to apply when pressure drops to 60 psi
- air constantly leaks from the exhaust port of a tractor relay valve when the
park brakes are released. What Should be done? - - check the related spring
brake chambers for hold-off pressure back-flow
- Which of the following terms have the same meaning as reluctor wheel? -
- Exciter ring
- How fast are the wheels turned on a diagnostic brake dynamometer? - - 1
mph
- Technician A says that a relay piston in a foot valve responds to pneumatic
signal from the primary section of the valve, by metering out into the
secondary circuit the same pressure that acts on it.
Technician B says that the further a primary piston travel though it's stroke
in a dual circuit foot valve, the more pressure is applied in opposition to foot
pressure.
Who is right? - - Both Technician A and B
- Technician A says that brake chambers convert air pressure into rotary
force.
, Technician B says that slack adjusters convert rotary force into linear force.
Who is correct. - - Neither Technicians
- Which of the following valves delays application force to front disk brakes
to balance a typical disk/drum hydraulic brake system? - - Metering valve
- Which valves on a current FMVSS-121 compliant highway tractor are used
to balance front and rear braking force under varying operating conditions? -
- automatic ration and bobtail proportioning valves
- What are the S-cam type foundation brakes mounted to? - - spider
- What is the reason for using different relay valve crack pressures in a
tractor trailer semi combination? - - balance the baking on the tractor and
the trailer.
- What legislation mandates every required standards of a highway truck air
brake system? - - FMVSS 121
- Which of the following conditions would be most likely to cause brakes not
to completely release? - - dirt build-up around service treadle
- Technician A says that most truck compressors today are seldom rebuilt in
the field today.
Technician B says that it most cases it is cost effective to rebuild
compressors in the shop rather than stock rebuilt/change units.
Who is correct? - - Technician A only
- In a truck air brake system, which sub-circuit is primarily responsible for
actuating front axle service brakes when the system is functioning normally?
- - secondary circuit
- Which of the following type of heavy truck foundation brakes can be
actuated by a power screw? - - disc brakes
- When the driver depresses the brake pedal of the typical truck with air-
over-hydraulic brakes, which of the following occurs? - - modulated air
pressure actuates pneumatic booster assemblies
- Technician A says that Rockwell automatic slack adjusters generally use
stroke-sensing adjustment on the release stroke.
and Answers
When you are installing open ancho brake shoes (such as Q-brakes) which of
the following steps should be performed first? - - install the upper brake
shoe
- Technician A says that in the event of a total failure of the primly circuit in
an FMVSS-121 compliant tractor-trailer combination, the rig can be brought
safely to a complete stop.
Technician B says that in the event of a total failure of the primary circuit the
relay section of the treadle calve will be actuated mechanically. Who is
correct? - - Both Technician A and B
- How many degrees of tire rotation does each tooth in a 100-tooth ABS
reluctor wheel represent? - - 3.6- degrees
- A system air pressure loss occurs on a trailer resulting in a gradual
pressure bleed down. Which of the following will occur first? - - spring brakes
on trailer begin to apply when pressure drops to 60 psi
- air constantly leaks from the exhaust port of a tractor relay valve when the
park brakes are released. What Should be done? - - check the related spring
brake chambers for hold-off pressure back-flow
- Which of the following terms have the same meaning as reluctor wheel? -
- Exciter ring
- How fast are the wheels turned on a diagnostic brake dynamometer? - - 1
mph
- Technician A says that a relay piston in a foot valve responds to pneumatic
signal from the primary section of the valve, by metering out into the
secondary circuit the same pressure that acts on it.
Technician B says that the further a primary piston travel though it's stroke
in a dual circuit foot valve, the more pressure is applied in opposition to foot
pressure.
Who is right? - - Both Technician A and B
- Technician A says that brake chambers convert air pressure into rotary
force.
, Technician B says that slack adjusters convert rotary force into linear force.
Who is correct. - - Neither Technicians
- Which of the following valves delays application force to front disk brakes
to balance a typical disk/drum hydraulic brake system? - - Metering valve
- Which valves on a current FMVSS-121 compliant highway tractor are used
to balance front and rear braking force under varying operating conditions? -
- automatic ration and bobtail proportioning valves
- What are the S-cam type foundation brakes mounted to? - - spider
- What is the reason for using different relay valve crack pressures in a
tractor trailer semi combination? - - balance the baking on the tractor and
the trailer.
- What legislation mandates every required standards of a highway truck air
brake system? - - FMVSS 121
- Which of the following conditions would be most likely to cause brakes not
to completely release? - - dirt build-up around service treadle
- Technician A says that most truck compressors today are seldom rebuilt in
the field today.
Technician B says that it most cases it is cost effective to rebuild
compressors in the shop rather than stock rebuilt/change units.
Who is correct? - - Technician A only
- In a truck air brake system, which sub-circuit is primarily responsible for
actuating front axle service brakes when the system is functioning normally?
- - secondary circuit
- Which of the following type of heavy truck foundation brakes can be
actuated by a power screw? - - disc brakes
- When the driver depresses the brake pedal of the typical truck with air-
over-hydraulic brakes, which of the following occurs? - - modulated air
pressure actuates pneumatic booster assemblies
- Technician A says that Rockwell automatic slack adjusters generally use
stroke-sensing adjustment on the release stroke.
