HEAVY TRUCK BRAKES MICHIGAN
MECHANIC STUDY GUIDE
QUESTIONS & A+ GRADED
ANSWERS
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.
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)
D. A RELAY VALVE.
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)
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)
B. A PLUGGED SAFETY VALVE. (NOT CORRECT AWNSER)
C. A ONE-WAY CHECK VALVE STUCK OPEN.
MECHANIC STUDY GUIDE
QUESTIONS & A+ GRADED
ANSWERS
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.
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)
D. A RELAY VALVE.
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)
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)
B. A PLUGGED SAFETY VALVE. (NOT CORRECT AWNSER)
C. A ONE-WAY CHECK VALVE STUCK OPEN.
