HEAVY TRUCK BRAKES MICHIGAN MECHANIC
STUDY GUIDE/ Q&A/ GRADED A+.
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.
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)
Page 1 of 15
, 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.
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? - A. THE SERVICE BRAKE CHAMBER
DIAPHRAGM HAS SPLIT. (POSSIBLE CORRECT AWNSER)
B. THE CAM HAS ROLLED OVER DUE TO TOO MUCH LINING WEAR.
C. THE ANTI-LOCK MODULE HAS BURNED OUT AT THE SENDING UNIT. (NOT
CORRECT AWNSER)
D. THE CHAMBER SPRING HAS RUSTED AND IS BROKEN.
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STUDY GUIDE/ Q&A/ GRADED A+.
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.
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)
Page 1 of 15
, 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.
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? - A. THE SERVICE BRAKE CHAMBER
DIAPHRAGM HAS SPLIT. (POSSIBLE CORRECT AWNSER)
B. THE CAM HAS ROLLED OVER DUE TO TOO MUCH LINING WEAR.
C. THE ANTI-LOCK MODULE HAS BURNED OUT AT THE SENDING UNIT. (NOT
CORRECT AWNSER)
D. THE CHAMBER SPRING HAS RUSTED AND IS BROKEN.
Page 2 of 15
