HEAVY TRUCK BRAKES MICHIGAN
MECHANIC STUDY GUIDE GRADED
A+
AN ENGINE BRAKE (JACOBS BRAKE) - Correct answer-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: - Correct answer-A.
AN INVERSION VALVE. (POSSIBLE CORRECT AWNSER)
B. A SAFETY VALVE.
C. A MODULATOR VALVE. (NOT CORRECT AWNSER)
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,D. A RELAY VALVE.
A MECHANIC HAS REMOVED A BRAKE DRUM AND FOUND THE BRAKE
LININGS SOAKED WITH GREASE. THE BRAKE LININGS SHOULD BE: -
Correct answer-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: -
Correct answer-A. AIR PRESSURE AT POINT F.
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? - Correct answer-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)
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, 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? - Correct answer-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: - Correct answer-A.
LIMITS PRESSURE BUILD UP IN THE SYSTEM.
B. STOPS THE FLOW TO DAMAGED BRAKE LINES.
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: - Correct answer-A. A GOVENOR THAT IS BAD OR OUT OF
ADJUSTMENT. (POSSIBLE CORRECT AWNSER)
©COPYRIGHT 2025, ALL RIGHTS RESERVED 3
MECHANIC STUDY GUIDE GRADED
A+
AN ENGINE BRAKE (JACOBS BRAKE) - Correct answer-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: - Correct answer-A.
AN INVERSION VALVE. (POSSIBLE CORRECT AWNSER)
B. A SAFETY VALVE.
C. A MODULATOR VALVE. (NOT CORRECT AWNSER)
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,D. A RELAY VALVE.
A MECHANIC HAS REMOVED A BRAKE DRUM AND FOUND THE BRAKE
LININGS SOAKED WITH GREASE. THE BRAKE LININGS SHOULD BE: -
Correct answer-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: -
Correct answer-A. AIR PRESSURE AT POINT F.
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? - Correct answer-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)
©COPYRIGHT 2025, ALL RIGHTS RESERVED 2
, 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? - Correct answer-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: - Correct answer-A.
LIMITS PRESSURE BUILD UP IN THE SYSTEM.
B. STOPS THE FLOW TO DAMAGED BRAKE LINES.
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: - Correct answer-A. A GOVENOR THAT IS BAD OR OUT OF
ADJUSTMENT. (POSSIBLE CORRECT AWNSER)
©COPYRIGHT 2025, ALL RIGHTS RESERVED 3
