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HEAVY TRUCK BRAKES
MICHIGAN MECHANIC STUDY
GUIDE Questions and Answers Latest
2026
AN ENGINE BRAKE (JACOBS BRAKE) Ans: 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: Ans:
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
© 2025 All rights reserved
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BRAKE LININGS SHOULD BE: Ans: 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: Ans: 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? Ans: 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
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UP RIGHT. WHAT COULD CAUSE THIS PROBLEM? Ans: 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: Ans:
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: Ans: 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? Ans: A.
VALVE AT A WILL PROTECT THE PRESSURE IN THE DRY
TANK.
© 2025 All rights reserved
HEAVY TRUCK BRAKES
MICHIGAN MECHANIC STUDY
GUIDE Questions and Answers Latest
2026
AN ENGINE BRAKE (JACOBS BRAKE) Ans: 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: Ans:
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
© 2025 All rights reserved
, 2 | Page
BRAKE LININGS SHOULD BE: Ans: 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: Ans: 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? Ans: 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
© 2025 All rights reserved
, 3 | Page
UP RIGHT. WHAT COULD CAUSE THIS PROBLEM? Ans: 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: Ans:
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: Ans: 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? Ans: A.
VALVE AT A WILL PROTECT THE PRESSURE IN THE DRY
TANK.
© 2025 All rights reserved
