HEAVY TRUCK BRAKES EXAMINATION TEST QUESTIONS AND ANSWERS 2025/2026

HEAVY TRUCK BRAKES EXAMINATION TEST QUESTIONS
AND ANSWERS 2025/2026
✔✔IN THE SYSTEM SHOWN BELOW, AIR LEAKS FROM THE RELAY VALVE
EXHAUST PORT ALL THE TIME. THE LIKELY CAUSE OF THIS PROBLEM IS: -
✔✔A. A LEAKY SEAL IN THE PART AT POINT D.
B. A LEAKY SEAL IN THE PART AT POINT C. (CORRECT AWNSER)
C. A LEAKY SEAL IN THE PART AT POINT E.
D. A LEKAY SEAL IN THE PART AT POINT A.

✔✔IN THE DRAWING BELOW, THE DIAPHRAGM AT POINT E HAS FAILED. WHAT
MUST YOU DO BEFORE MOVING THE TRUCK? - ✔✔A. COMPRESS THE SPRING
AT POINT D. (NOT CORRECT AWNSER)
B. APPLY AIR PRESSURE TO POINT F.
C. COMPRESS THE SPRING AT POINT F.
D. RELEASE AIR PRESSURE AT AREA B.

✔✔IN THE DRAWING BELOW: - ✔✔A. THE PARKING BRAKES ARE APPLIED AND
THE SERVICE BRAKES ARE RELEASED.
B. BOTH PARKING AND SERVICE BRAKES ARE RELEASED.
C. THE SERVICE BRAKES ARE APPLIED AND THE PARKING BRAKES ARE
RELEASED.
D. BOTH PARKING AND SERVICE BRAKES ARE APPLIED. (NOT CORRECT
AWNSER)

✔✔THE TRAILER BRAKES DO NOT RELEASE PROPERLY. THE AIR PRESSUREIS
NORMAL AND THE EMERGENCY SERVICE LINES ARE HOOKED UP PROPERLY.
THE PROBLEM COULD BE CAUSED BY: - ✔✔A. DRY OR BINDING CAM
BUSHINGS.
B. A BAD RELAY EMERGENCY VALVE.
C. A FOOT VALVE NOT RETURNING TO A FULLY RELEASED POSITION.
D. ALL OF THE ABOVE. (CORRECT AWNSER)

✔✔WHAT SHOULD YOU DO FIRST BEFORE REPLACING THE DIAPHRAGM ON A
SPRING BRAKE TYPE EMERGENCY BRAKE CHAMBER? - ✔✔A. COMPRESS THE
SPRING BRAKE. (POSSIBLE CORRECT AWNSER)
B. BACK OFF THE SLACK ADJSUTER.
C. DISCONNECT THE PUSH ROD CLEVIS.
D. COMPRESS THE DIAPHRAGM RETURN SPRING. (NOT CORRECT AWNSER)

✔✔CAM ACTUATED BRAKE SHOES ARE FOUND TO BE MAKING ONLY PARTIAL
CONTACT WITH THE DRUM. TO CORRECT THIS CONDITION, ADJUSTMENT
SHOULD BE MADE TO THE: - ✔✔A. ACTUATOR CABLE.
B. APPLYING WEDGE.
C. ECCENTRIC ANCHOR PINS. (CORRECT AWNSER)

, D. ROLLER FOLLOWER.

✔✔WATER SHOULD BE DRAINED FROM AIR RESERVOIRS: - ✔✔A. BEFORE
ADJUSTING SLACK ADJUSTERS.
B. DAILY OR MORE FREQUENTLY IN COLD OR MOIST WEATHER. (CORRECT
AWNSER)
C. BEFORE ANY ATTEMPT IS MADE TO REPLACE A SERVICE CHAMBER
DIAPHRAGM.
D. TO EXPEL EXCESS OIL PASSED BY THE AIR PUMP.

✔✔A MECHANIC FINDS THAT THE VACUUM HOSE HOOKS UP TO THE POWER
BOOSTER HAS COLLAPSED. WHAT SHOULD THE MECHANIC DO? - ✔✔A.
REPLACE THE HOSE. (POSSIBLE CORRECT AWNSER)
B. REPLACE THE CHECK VALVE.
C.REPLACE THE BOOSTER.
D. ALL OF THE ABOVE. (NOT CORRECT AWNSER)

✔✔HYDRAULIC BRAKE LINES ARE MADE OF: - ✔✔A. ALUMINUM.
B. REINFORCED BRASS.
C. SEAMLESS COPPER TUBING.
D. STEEL. (CORRECT AWNSER)

✔✔WHAT IS THE PROPER LUBRICANT TO USE WHEN ASSEMBLING A WHEEL
CYLINDER? - ✔✔A. BRAKE FLUID. (CORRECT AWNSER)
B. OLEUM SPIRITS.
C. MINERAL OIL.
D. LITHIUM BASED GREASE.

✔✔A COMPRESSOR MAY NOT UNLOAD BECAUSE: - ✔✔A. THE UNLOADER IS
BINDING OR STUCK. (CORRECT AWNSER)
B. THE EXHAUST VALVES ARE LEAKY OR STUCK OPEN.
C. THE DOUBLE CHECK VALVE IS STUCK.
D. THE INLET AIR FILTER IS PLUGGED.

✔✔THE WEAR SLEEVE IS LOCATED: - ✔✔A. IN THE BRAKE DRUM. (NOT
CORRECT AWNSER)
B. IN THE CHAMBER HOUSING.
C. ON THE AXLE SPINDLE. (POSSIBLE CORRECT AWNSER)
D. IN THE HUB.

✔✔IN THE TRACTOR TRAILER SYSTEM BELOW, THE TRACTOR PROTECTION
VALVE IS AT: - ✔✔A. POINT E. (NOT CORRECT AWNSER)
B. POINT A.
C. POINT B.
D. POINT C. (POSSIBLE CORRECT AWNSER)