HEAVY TRUCK BRAKES MICHIGAN MECHANIC STUDY GUIDE

HEAVY TRUCK BRAKES MICHIGAN MECHANIC STUDY GUIDE “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)" "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. D. A STICKY QUICK RELEASE VALVE." "IF GLADHAND 2 IS UNHOOKED OR HAS A SEVERE LEAK, WHAT WILL HAPPEN DURING OPERATION? - CORRECT ANSWER 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." "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? - CORRECT ANSWER 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? - CORRECT ANSWER 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? - CORRECT ANSWER 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: - CORRECT ANSWER A. POINT E. B. POINT D. C. POINT B. D. POINT A. (CORRECT AWNSER)" "WHICH ONE OF THESE SHOULD BE DONE MOST FREQUENTLY? - CORRECT ANSWER A. ADJUST THE SPIDERS. B. LUBRICATE THE "S" CAM. C. CHECK THE BRAKE CHAMBERS FOR MOISTURE. (NOT CORRECT AWNSER) D. CHECK THE BRAKE CHAMBER PUSH ROD TRAVEL. (POSSIBLE CORRECT AWNSER)" "AIR BRAKE LINES ARE MSOT OFTEN MADE OF: - CORRECT ANSWER A. BRASS AND ALUMINUM. B. STEELAND NYLON. C. NYLON AND BRASS. D. COPPER AND NYLON. (CORRECT AWNSER)" "TO FIND LEAKS IN AIRLINE FITTINGS AND SERVICE CHAMBERS, YOU SHOULD USE: - CORRECT ANSWER A. A HALIDE LEAK DETECTOR. B. A VACUUM GAUGE. (NOT CORRECT AWNSER) C. A BRAKE PRESSURE BLEEDER. D. A SOAP SUDS MIXTURE. (POSSIBLE CORRECT AWNSER)" "A LIKELY CAUSE OF GRABBING BRAKES ON A DRIVE AXLE WOULD BE: - CORRECT ANSWER A. A BAD QUICK RELEASE VALVE. (NOT CORRECT AWNSER) B. BRAKES ADJUSTED TOO TIGHT. (POSSIBLE CORRECT AWNSER) C. GREASE OR GEAR LUBE ON LININGS. D. WEAK SHOE RETURN SPRINGS." "THE HYDRAULIC SERVICE BRAKES WILL NOT RELEASE FULLY. WHAT SHOULD YOU DO FIRST? - CORRECT ANSWER A. CHECK THE MASTER CYLINDER FOR DEFECTS. (CORRECT AWNSER) B. CHECK FOR A DEFECTIVE QUICK RELEASE VALVE. C. RUN AN ENGINE VACUUM TEST. D. CHECK THE BRAKE DRUMS." "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: - CORRECT ANSWER 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? - CORRECT ANSWER 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: - CORRECT ANSWER A. ACTUATOR CABLE. B. APPLYING WEDGE. C. ECCENTRIC ANCHOR PINS. (CORRECT AWNSER) D. ROLLER FOLLOWER." "WHAT IS THE PROPER LUBRICANT TO USE WHEN ASSEMBLING A WHEEL CYLINDER? - CORRECT ANSWER A. BRAKE FLUID. (CORRECT AWNSER) B. OLEUM SPIRITS. C. MINERAL OIL. D. LITHIUM BASED GREASE." "A COMPRESSOR MAY NOT UNLOAD BECAUSE: - CORRECT ANSWER 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: - CORRECT ANSWER 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: - CORRECT ANSWER A. POINT E. (NOT CORRECT AWNSER) B. POINT A. C. POINT B. D. POINT C. (POSSIBLE CORRECT AWNSER)" "AN AIR OVER HYDRAULIC POWER CLUSTER: - CORRECT ANSWER A. CONSISTS OF AN AIR RESERVOIR MOUNTED DIRECTLY OVER A HYDRAULIC RESERVOIR TO APPLY THE BRAKES IN CASE OF A HYDRAULIC BRAKE FAILURE. (NOT CORRECT AWNSER) B. USES A HYDRAUILIC BRAKE APPLICATION IN CASE OF AN AIR FAILURE. C. USES AIR PRESSURE TO BOOST THE HYDRAULIC PRESSURE IN A BRAKE SYSTEM. (POSSIBLE CORRECT AWNSER) D. NONE OF THE ABOVE." "THE AIR CHARGES THE TRAILER RESERVOIR IS SUPPLIED FROM THE MAIN RESERVOIR TO: - CORRECT ANSWER A. PART A, TO PART D, TO THE FOOT VALVE, TO PART E, TO PART C, THEN THROUGH GLADHAND 2 TO PART B. B. THE FOOT VALVE, TO PART D, TO PART C, THEN THROUGH GLADHAND 2 TO PART B. C. VALVE E, TO PART C, TO PART B. D. PART A, TO PART D, TO PART C, THEN THROYGH GLADHAND 1 TO PART B. (NOT CORRECT AWNSER)" "WITH THE AIR BRAKES IN THE APPLIED POSITION ON A TRACTOR TRAILER, WHAT IS AN ACCEPTABLE AIR PRESSURE LOSS IN THE SYSTEM? - CORRECT ANSWER A. THE PRESSURE SHOULD NOT DROP AT ALL IN PERIOD OF ONE MINUTE. (NOT CORRECT AWNSER) B. 25 PSI/MINUTE. C. 15 PSI/MINUTE. D. 4 PSI/MINUTE. (POSSIBLE CORRECT AWNSER)" "APPROXIMATELY WHAT AIR PRESSURE WILL BE REQUIRED ON A FAIL SAFEOR SPRING BRAKE STYLE PARKING BRAKE TO HOLD OFF THE SPRING BRAKES? - CORRECT ANSWER A. 120-150 PSI. B. 10 PSI-15 PSI. C. 60 PSI-80 PSI. (CORRECT AWNSER) D. 5 PSI." "THE AIR PRESSURE IN THE SYSTEM IS BELOW NORMAL, WHAT IS THE MOST LIEKLY CAUSE: - CORRECT ANSWER A. A FROZEN TWO-WAY CHECK VALVE. B. A PLUGGED SAFETY VALVE. C. A DEFECTIVE COMPRESSOR GOVENOR. (POSSIBLE CORRECT AWNSER) D. ALL OF THE ABOVE. (NOT CORRECT AWNSER)" "IN AN "S" CAM BRAKE, THE CHAMBER PUSH ROD IS RETURNED TO ITS RELEASED POSITION BY: - CORRECT ANSWER A. THE BRAKE CHAMBER DIAPHRAGM. B. THE BRAKE SLACK ADJUSTERS. C. A SPRING IN THE BRAKE CHAMBER. (CORRECT AWNSER) D. AIR PRESSURE." "A PULSATING BRAKE PEDAL IN A HYDRAULIC STSTEM CAN BE CAUSED BY: - CORRECT ANSWER A. AN OUT-OF-ROUND DRUM. (CORRECT AWNSER) B. A DEFECTIVE MASTER CYLINDER. C. A DEFECTIVE COMBINATION VALVE. D. A BAD VACUUM BOOSTER." "THE EMERGENCY BRAKE LINE ON MOST TRAILERS IS INSTALLED: - CORRECT ANSWER A. WITHOUT GLADHANDS. B. AS TWO LINES, ONE ON EACH SIDE OF THE TRAILER. (NOT CORRECT AWNSER) C. ON THE DRIVER SIDE OR LEFT SIDE. (POSSIBLE CORRECT AWNSER) D. ON THE CURB OR RIGHT SIDE." "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." "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." "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)" "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? - CORRECT ANSWER 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." "TOO MUCH EFFORT IS REQUIRED ON THE BRAKE PEDAL TO STOP A TRUCK WITH A VACUUM BOOSTER. WHAT IS THE LIKELY CAUSE OF THIS PROBLEM? - CORRECT ANSWER A. SEIZED AUTOMATIC ADJUSTERS. B. GLAZED LININGS C. A DEFECTIVE MODULATOR VALVE. (NOT CORRECT AWNSER) D. VERY HIGH ENGINE VACUUM. (POSSIBLE CORRECT AWNSER)" "WITH THE VALVE PICTURED BELOW, THE OPERATOR CAN: - CORRECT ANSWER 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: - CORRECT ANSWER 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)" "MOST ANTI-SKID BRAKING SYSTEMS OPERATE BY MODULATING THE BRAKES SIMULTANEOUSLY ON: - CORRECT ANSWER 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: - CORRECT ANSWER 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? - CORRECT ANSWER 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? - CORRECT ANSWER 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: - CORRECT ANSWER 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? - CORRECT ANSWER 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)" "A MECHANIC FINDS THAT THE BRAKE LINING IS WORN VERY MUCH NEAR THE EDGE. WHAT WOULD CAUSE THIS TO HAPPEN? - CORRECT ANSWER A. BELL MOUTHED BRAKE DRUMS. B. WORN-OUT ANCHOR PIN HOLES IN THE BRAKE SHOE. C. A BENT BRAKE SHOE WEB. D. ALL OF THE ABOVE. (CORRECT AWNSER)" "IN THE SYSTEM SHOWN BELOW, AIR LEAKS FROM THE RELAY VALVE EXHAUST PORT ALL THE TIME. THE LIKELY CAUSE OF THIS PROBLEM IS: - CORRECT ANSWER 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? - CORRECT ANSWER 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: - CORRECT ANSWER 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)" "WATER SHOULD BE DRAINED FROM AIR RESERVOIRS: - CORRECT ANSWER 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? - CORRECT ANSWER 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: - CORRECT ANSWER A. ALUMINUM. B. REINFORCED BRASS. C. SEAMLESS COPPER TUBING. D. STEEL. (CORRECT AWNSER)"