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HEAVY TRUCK BRAKES MICHIGAN MECHANIC STUDY
GUIDE QUESTIONS WITH CORRECT ANSWERS
"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."
"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)"
"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 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." "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.
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)"
"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." "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)"
"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. 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."
“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." "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)"
