Heavy Duty Truck Systems – Chapter 31 – Lecture Summary & Practice Questions
Which of the following is the best practice when instructed to block the wheels on a
tractor/trailer combination? - correct answer ✔✔Place a pair of wedged wheel chocks on one
tractor drive axle and one trailer axle wheel.
What is the required amount of slack adjuster free travel on a properly adjusted, manual S-cam
brake? - correct answer ✔✔3/8 to 5/8 inch
Which of the following foundation brake components are lubricated with chassis grease, either
for component life or as part of a lube job? - correct answer ✔✔S-cam bushings
A 161/2 inch brake drum specified to have a machine limit of 0.090 inch over and a maximum
dimension of 0.120 inch over is measured at 0.098 inch over at a brake overhaul. Technician A
says that the drum can be turned on a drum lathe, providing that the maximum dimension of
0.120 inch is observed. Technician B says that the drum can be legally returned to service
without being turned. Who is correct? - correct answer ✔✔Technician B only
A tandem axle trailer equipped with S-cam brakes has all four slack adjusters originally set with
a 6-inch dimension from the clevis pin to the camshaft. One slack adjuster is replaced, and
because of a different hole arrangement in the new slack adjuster, it is set at 61/2 inches. Which
of the following is more likely to result? - correct answer ✔✔One of the four wheels will lock up
ahead of the others under severe braking
When adjusting a manual slack adjuster on an S-cam foundation brake, Technician A says that
the lock collar should be retracted and the adjusting nut always rotated clockwise to decrease
free travel. Technician B says that free travel can be reduced only when the adjusting nut is
rotated counterclockwise. Who is correct? - correct answer ✔✔Neither A nor B
A set of brake linings has become glazed because of oil saturation by a failed wheel seal.
Technician A says that pressure washing the foundation brake components should be sufficient
Which of the following is the best practice when instructed to block the wheels on a
tractor/trailer combination? - correct answer ✔✔Place a pair of wedged wheel chocks on one
tractor drive axle and one trailer axle wheel.
What is the required amount of slack adjuster free travel on a properly adjusted, manual S-cam
brake? - correct answer ✔✔3/8 to 5/8 inch
Which of the following foundation brake components are lubricated with chassis grease, either
for component life or as part of a lube job? - correct answer ✔✔S-cam bushings
A 161/2 inch brake drum specified to have a machine limit of 0.090 inch over and a maximum
dimension of 0.120 inch over is measured at 0.098 inch over at a brake overhaul. Technician A
says that the drum can be turned on a drum lathe, providing that the maximum dimension of
0.120 inch is observed. Technician B says that the drum can be legally returned to service
without being turned. Who is correct? - correct answer ✔✔Technician B only
A tandem axle trailer equipped with S-cam brakes has all four slack adjusters originally set with
a 6-inch dimension from the clevis pin to the camshaft. One slack adjuster is replaced, and
because of a different hole arrangement in the new slack adjuster, it is set at 61/2 inches. Which
of the following is more likely to result? - correct answer ✔✔One of the four wheels will lock up
ahead of the others under severe braking
When adjusting a manual slack adjuster on an S-cam foundation brake, Technician A says that
the lock collar should be retracted and the adjusting nut always rotated clockwise to decrease
free travel. Technician B says that free travel can be reduced only when the adjusting nut is
rotated counterclockwise. Who is correct? - correct answer ✔✔Neither A nor B
A set of brake linings has become glazed because of oil saturation by a failed wheel seal.
Technician A says that pressure washing the foundation brake components should be sufficient
