LATEST UPDATED HEAVY TRUCK BRAKES
MICHIGAN MECHANIC (ACTUAL 2025) STUDY GUIDE
an engine brake (jacobs brake) - <<,answers>>>>a. is a self-
energizing servo type.
b. is normally used in place of a spring brake.
c. restricts the intake port and causes a build up of 30-45 lbs
of pressure.
d. opens the exhaust valves near the top of the compression
stroke to release the compressed air. (correct awnser)
in the system shown below, the part at c is: -
<<,answers>>>>a. an inversion valve. (possible correct
awnser)
b. a safety valve.
c. a modulator valve. (not correct awnser)
d. a relay valve.
a mechanic has removed a brake drum and found the brake
linings soaked with grease. the brake linings should be: -
<<,answers>>>>a. replaced. (correct awnser)
b. sanded to roughen up the friction surface.
c. dipped in lacquer thinner.
d. washed with denatured alcohol.
in the drawing below, the parking brakes are applied by: -
<<,answers>>>>a. air pressure at point f.
, LATEST UPDATED HEAVY TRUCK BRAKES
MICHIGAN MECHANIC (ACTUAL 2025) STUDY GUIDE
b. vacuum in area b.
c. spring at point c.
d. pressure in area a. (not correct awnser)
what is the purpose of a vacuum booster? - <<,answers>>>>
a. to decrease brake pedal effort. (possible correct awnser)
b. to prevent fade under heavy braking.
c. to provide assistance when the engine vacuum is low. (not
correct awnser)
d. to maintain uniform pedal travel as the linings wear.
the trailer brakes do not work. the tractor system is at normal
pressure. there are no leaks and the service and emergency
lines are hooked up right. what could cause this problem? -
<<,answers>>>>a. ice in the lines at the trailer.
b. a bad relay valve.
c. a bad safety relief valve.
d. both a and b. (correct awnser)
the residual valve in the master cylinder: - <<,answers>>>>a.
limits pressure build up in the system.
b. stops the flow to damaged brake lines.
, LATEST UPDATED HEAVY TRUCK BRAKES
MICHIGAN MECHANIC (ACTUAL 2025) STUDY GUIDE
c. keeps some pressure in the sytem when the brakes are
released. (correct awnser)
d. is operated by engine vacuum.
higher than normal air pressure would likely be caused by: -
<<,answers>>>>a. a govenor that is bad or out of adjustment.
(possible correct awnser)
b. a plugged safety valve. (not correct awnser)
c. a one-way check valve stuck open.
d. a sticky quick release valve.
if gladhand 2 is unhooked or has a severe leak, what will
happen during operation? - <<,answers>>>>a. valve at a will
protect the pressure in the dry tank.
b. tractor brakes will apply automatically. (not correct awnser)
c. valve at c will apply trailer brakes.
d. valve at b will apply trailer brakes.
during a hard stop, one brake has locked on a trailer with "s"
cam brakes. the service and emergency lines are hooked up
properly and the system is at normal pressure but the brakes
will not release. what is the likely cause of this problem? -
<<,answers>>>>a. the service brake chamber diaphragm has
split. (possible correct awnser)
MICHIGAN MECHANIC (ACTUAL 2025) STUDY GUIDE
an engine brake (jacobs brake) - <<,answers>>>>a. is a self-
energizing servo type.
b. is normally used in place of a spring brake.
c. restricts the intake port and causes a build up of 30-45 lbs
of pressure.
d. opens the exhaust valves near the top of the compression
stroke to release the compressed air. (correct awnser)
in the system shown below, the part at c is: -
<<,answers>>>>a. an inversion valve. (possible correct
awnser)
b. a safety valve.
c. a modulator valve. (not correct awnser)
d. a relay valve.
a mechanic has removed a brake drum and found the brake
linings soaked with grease. the brake linings should be: -
<<,answers>>>>a. replaced. (correct awnser)
b. sanded to roughen up the friction surface.
c. dipped in lacquer thinner.
d. washed with denatured alcohol.
in the drawing below, the parking brakes are applied by: -
<<,answers>>>>a. air pressure at point f.
, LATEST UPDATED HEAVY TRUCK BRAKES
MICHIGAN MECHANIC (ACTUAL 2025) STUDY GUIDE
b. vacuum in area b.
c. spring at point c.
d. pressure in area a. (not correct awnser)
what is the purpose of a vacuum booster? - <<,answers>>>>
a. to decrease brake pedal effort. (possible correct awnser)
b. to prevent fade under heavy braking.
c. to provide assistance when the engine vacuum is low. (not
correct awnser)
d. to maintain uniform pedal travel as the linings wear.
the trailer brakes do not work. the tractor system is at normal
pressure. there are no leaks and the service and emergency
lines are hooked up right. what could cause this problem? -
<<,answers>>>>a. ice in the lines at the trailer.
b. a bad relay valve.
c. a bad safety relief valve.
d. both a and b. (correct awnser)
the residual valve in the master cylinder: - <<,answers>>>>a.
limits pressure build up in the system.
b. stops the flow to damaged brake lines.
, LATEST UPDATED HEAVY TRUCK BRAKES
MICHIGAN MECHANIC (ACTUAL 2025) STUDY GUIDE
c. keeps some pressure in the sytem when the brakes are
released. (correct awnser)
d. is operated by engine vacuum.
higher than normal air pressure would likely be caused by: -
<<,answers>>>>a. a govenor that is bad or out of adjustment.
(possible correct awnser)
b. a plugged safety valve. (not correct awnser)
c. a one-way check valve stuck open.
d. a sticky quick release valve.
if gladhand 2 is unhooked or has a severe leak, what will
happen during operation? - <<,answers>>>>a. valve at a will
protect the pressure in the dry tank.
b. tractor brakes will apply automatically. (not correct awnser)
c. valve at c will apply trailer brakes.
d. valve at b will apply trailer brakes.
during a hard stop, one brake has locked on a trailer with "s"
cam brakes. the service and emergency lines are hooked up
properly and the system is at normal pressure but the brakes
will not release. what is the likely cause of this problem? -
<<,answers>>>>a. the service brake chamber diaphragm has
split. (possible correct awnser)
