HEAVY TRUCK BRAKES MICHIGAN
MECHANIC STUDY GUIDE EXAM
QUESTIONS AND ANSWERS 100% PASS
AN ENGINE BRAKE (JACOBS BRAKE) - ✔✔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: - ✔✔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: - ✔✔A. REPLACED.
(CORRECT AWNSER)
B. SANDED TO ROUGHEN UP THE FRICTION SURFACE.
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©JOSHCLAY 2025/2026. YEAR PUBLISHED 2025.
,C. DIPPED IN LACQUER THINNER.
D. WASHED WITH DENATURED ALCOHOL.
IN THE DRAWING BELOW, THE PARKING BRAKES ARE APPLIED BY: - ✔✔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? - ✔✔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? - ✔✔A. ICE IN THE
LINES AT THE TRAILER.
B. A BAD RELAY VALVE.
C. A BAD SAFETY RELIEF VALVE.
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©JOSHCLAY 2025/2026. YEAR PUBLISHED 2025.
, D. BOTH A AND B. (CORRECT AWNSER)
THE RESIDUAL VALVE IN THE MASTER CYLINDER: - ✔✔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: - ✔✔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? - ✔✔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.
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©JOSHCLAY 2025/2026. YEAR PUBLISHED 2025.
MECHANIC STUDY GUIDE EXAM
QUESTIONS AND ANSWERS 100% PASS
AN ENGINE BRAKE (JACOBS BRAKE) - ✔✔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: - ✔✔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: - ✔✔A. REPLACED.
(CORRECT AWNSER)
B. SANDED TO ROUGHEN UP THE FRICTION SURFACE.
Page 1 of 16
©JOSHCLAY 2025/2026. YEAR PUBLISHED 2025.
,C. DIPPED IN LACQUER THINNER.
D. WASHED WITH DENATURED ALCOHOL.
IN THE DRAWING BELOW, THE PARKING BRAKES ARE APPLIED BY: - ✔✔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? - ✔✔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? - ✔✔A. ICE IN THE
LINES AT THE TRAILER.
B. A BAD RELAY VALVE.
C. A BAD SAFETY RELIEF VALVE.
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©JOSHCLAY 2025/2026. YEAR PUBLISHED 2025.
, D. BOTH A AND B. (CORRECT AWNSER)
THE RESIDUAL VALVE IN THE MASTER CYLINDER: - ✔✔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: - ✔✔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? - ✔✔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.
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©JOSHCLAY 2025/2026. YEAR PUBLISHED 2025.
