HEAVY TRUCK BRAKES STUDY GUIDE QUESTIONS AND ANSWERS 2025/2026

HEAVY TRUCK BRAKES STUDY GUIDE QUESTIONS AND
ANSWERS 2025/2026
✔✔WITH THE VALVE PICTURED BELOW, THE OPERATOR CAN: - ✔✔A. APPLY
THE TRACTOR BRAKES BY SPRING PRESSURE. (NOT CORRECT AWNSER)
B. APPLY THE TRAILER BRAKES BY AIR PRESSURE.
C. ENGAGE OR DISENGAGE THE PARKING BRAKES.
D. APPLY THE TRAILER BRAKES BY SPRING PRESSURE.

✔✔IT IS FOUND THAT THE RUBBER DIAPHRAGM IN A MASTER CYLINDER
COVER IS SWOLLEN TO NEARLY DOUBLE IN SIZE. THIS COULD BE CAUSED BY:
- ✔✔A. CONTAMINATION OF THE BRAKE FLUID WITH ENGINE OIL. (POSSIBLE
CORRECT AWNSER)
B. ACCIDENTAL MIXING WITH SILICONE BRAKE FLUID.
C. MOISTURE IN THE BRAKE FLUID.
D. ALL OF THE ABOVE. (NOT CORRECT AWNSER)

✔✔WITH THE ENGINE STOPPED, A MECHANIC HOLDS THE POWER BRAKE
PEDAL IN THE DEPRESSED POSITION. THE MECHANIC THE STARTS THE
ENGINE WITH THE PEDAL STILL DEPRESSED. THE PEDAL SINKS SLIGHTLY.
WHAT DOES THIS INDICATE? - ✔✔A. THE BRAKE BOOSTER IS SATISFACTORY.
(CORRECT AWNSER)
B. A LEAKING CHECK VALVE.
C. A TORN DIAPHRAGM.
D. A DEFECTIVE CONTROL VALVE ASSEMBLY.

✔✔A MECHANIC FINDS GEAR LUBE INSIDE BOTH BRAKE DRUMS ON A DRIVING
AXLE. WHAT IS THE MOST LIKELY CAUSE OF THIS PROBLEM? - ✔✔A. A BAD
PINION SEAL.
B. A PLUGGED AXLE VENT. (CORRECT AWNSER)
C. A BAD WHEEL BEARING.
D. A BAD DIFFERENTIAL CASE SEAL.

✔✔WHEN COMPLETING A BRAKE RELINE, WHAT BRAKE LINKAGE SHOULD THE
MECHANIC LUBRICATE? - ✔✔A. THE ANCHOR PINS.
B. THE CAMSHAFTS. (POSSIBLE CORRECT AWNSER)
C. THE SLACK ADJUSTER. (NOT CORRECT AWNSER)
D. ALL OF THE ABOVE.

✔✔IN THE SYSTEM SHOWN BELOW, A QUICK RELEASE VALVE WOULD BE
NEEDED AT: - ✔✔A. POINT E.
B. POINT D.
C. POINT B.
D. POINT A. (CORRECT AWNSER)

, ✔✔MOST ANTI-SKID BRAKING SYSTEMS OPERATE BY MODULATING THE
BRAKES SIMULTANEOUSLY ON: - ✔✔A. OPPOSITE CORNERS OF THE VEHICLE.
B. NON-DRIVING AXLES ONLY.
C. THE SAME AXLE. (CORRECT AWNSER)
D. THE SAME SIDE OF THE VEHICLE.

✔✔WITH THE BRAKES FULLY APPLIED AND PROPERLY ADJSUTED, THE ANGLE
BETWEEN THE PUSHROD AND SLACK ADJUSTER SHOULD NOT BE MORE
THAN: - ✔✔A. 30 DEGREES.
B. 45 DEGREES. (NOT CORRECT AWNSER)
C. 90 DEGREES. (CORRECT AWNSER)
D. 60 DEGREES.

✔✔A MECHANIC IS REPLACING A MASTER CYLINDER. THE PUSH ROD (SEE
BELOW) IS ACCIDENTALLY PULLED OUT AND PART X FALLS OUT OF PLACE.
WHAT WILL CAUSE THIS? - ✔✔A. EXTREME PEDAL SENSITIVITY.
B. EXCESSIVE PEDAL TRAVEL.
C. EXCESSIVE BRAKE FLUID LOSS.
D. BOTH A AND B. (CORRECT AWNSER)

✔✔WHAT IS THE FUNCTION OF THE INVERSION VALVE USED ON A STRAIGHT
TRUCK WITH DUAL AIR BRAKE SYSTEM? - ✔✔A. IT ALLOWS A MODULATED
SPRING BRAKE APPLICATION ON THE REAR AXLE IF AIR PRESSURE IS APPLIED
TO IT.
B. IT PREVENTS THE SPRING BRAKE FROM APPLYING DURING PERIODS OF
LOW AIR PRESSURE BECAUSE OF A PANIC STOP.
C. IT REVERSES THE SIRECTION OF THE AIR IN THE PRIMARY SYSTEM TO
HELP RELEASE THE BRAKES.
D. IT ALLOWS A MODULATED SPRING BRAKE APPLICATION IN AN AIR LOSS
OCCURS IN THE PRIMARY PORTION OF THE SYSTEM. (CORRECT AWNSER)

✔✔THE UNIT SHOWN BELOW IS: - ✔✔A. AN ANTI-SKID RELAY EMERGENCY
VALVE.
B. A SPRING BRAKE CHAMBER.
C. A VACUUM BOOSTER. (CORRECT AWNSER)
D. A SEQUECE/PRIORITY VALVE.

✔✔WHICH OF THE FOLLOWING WILL NOT CAUSE BRAKE CHATTER? - ✔✔A.
WORN ANCHOR PIN HOLES IN SHOES.
B. A STICKY OR RUSTY GOVENOR PISTON. (POSSIBLE CORRECT AWNSER)
C. WORN CAM BUSHINGS.
D. LOOSE WHEEL BEARINGS. (NOT CORRECT AWNSER)