Download Heavy Truck Brakes Michigan Mechanic Study Guide 2025: Actual Exam Questions and Solutions and more Exams Mechanics in PDF only on Docsity!
HEAVY TRUCK BRAKES MICHIGAN MECHANIC
STUDY GUIDE 2025|ACTUAL EXAM WITH 100%
VERIFIED QUESTIONS AND CORRECT
SOLUTIONS| GUARANTEED A+
What is the function of the inversion valve used on a straight truck with dual air brake system? - correct_answ_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_answ_a. an anti-skid relay emergency valve.
b. a spring brake chamber.
c. a vacuum booster. (correct awnser)
d. a sequece/priority valve.
An engine brake (jacobs brake) - correct_answ_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)
Which of the following will not cause brake chatter? - correct_answ_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_answ_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_answ_a. adjust the spiders.
d. weak shoe return springs.
The hydraulic service brakes will not release fully. what should you do first? - correct_answ_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_answ_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_answ_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_answ_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:
- correct_answ_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_answ_a. compress the spring brake. (possible correct awnser)
b. back off the slack adjsuter.
c. disconnect the push rod clevis.
d. all of the above. (not correct awnser)
Hydraulic brake lines are made of: - correct_answ_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_answ_a. brake fluid. (correct awnser)
b. oleum spirits.
c. mineral oil.
d. lithium based grease.
A compressor may not unload because: - correct_answ_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_answ_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_answ_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_answ_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 pressure in the system is below normal, what is the most liekly cause: - correct_answ_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_answ_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_answ_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_answ_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_answ_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_answ_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_answ_a. air pressure at point f.
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_answ_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_answ_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_answ_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_answ_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_answ_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_answ_a. contamination of the brake fluid with engine oil. (possible correct awnser)
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_answ_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: - correct_answ_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_answ_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_answ_a. extreme pedal sensitivity.
b. excessive pedal travel.
c. excessive brake fluid loss.
d. both a and b. (correct awnser)
