Exam 28: Truck Brake Systems

Technician A says that Rockwell automatic slack adjusters generally use stroke-sensing adjustment on the release stroke.Technician B says that Gunnite slack adjusters use clearance-sensing adjustment on the apply stroke.Who is correct?

When a FMVSS-121 compliant tractor-trailer combination is moving down the highway at a speed of 50 mph,which of the following circuits MUST be charged with air?

Which of the following would be more likely to meet the FMVSS-121 2010 shorter stopping distances?

Where should grease be applied on an S-cam brake system components?

Given that energy forms can only be altered not eliminated by mechanical action,what is the energy of motion ultimately converted to by a vehicle brake system?

If a truck is FMVSS 121 compliant,which of the following air reservoirs must be incorporated into the air brake circuit?

When S-cam brakes are properly adjusted,which of the following conditions will result in the most service brake torque?

Which of the following correctly describes the function of an automatic slack adjuster?

When should you cage a spring brake chamber?

What pressure is a pop-off valve set to trip at in most highway truck applications?

Which of the following terms is used to describe an air brake treadle valve on a CMVSS 121 compliant highway tractor?

What is the primary function of a relay valve?

Technician A says that for an air brake system to be FMVSS-121 compliant,there must be a minimum of 3 air reservoirs on a truck.Technician B says that some OEMs use a single air tank,divided into 3 separate chambers each with its own dump valve to meet FMVSS-121 requirements.Who is correct?

Which of the following type of heavy truck foundation brakes can be actuated by a power screw?

Which of the following service application valves is sometimes referred to by truck drivers as a trolley valve or spike?

How is the relay (secondary)section of an FMVSS-121 compliant dual-circuit foot valve actuated when the air brake circuit is functioning properly?

What is the function of a quick release valve when used in a front service brake circuit?

Technician A says that a closed-anchor brake shoe web encloses the anchor pin it pivots on.Technician B says that most current truck S-cam brake systems use closed-anchor brake shoes.Who is correct?

Technician A says that dual-actuated wedge brakes have better mechanical efficiency than air-actuated S-cam brakes.Technician B says that air-actuated S-cam brakes provide better stopping power than air-actuated disc brakes.Who is correct?

When under severe braking,the wheels of a trailer lock causing it to spin around while the tractor remains in a straight-ahead position,the condition is known as: