Heavy Duty Truck Systems - Chapter 28 exam questions and answers

Which of the following air brake system components functions as a lever? the slack adjuster Which of the following components sets the system cut-in and cut-out pressures? the governor What is the function of a system safety pop-off valve? It relieves pressure from the supply tank in the event of governor cut-out failure. The function of the foot valve or dual-circuit application valve is to: meter air to the service brake circuit The potential energy of an air brake system is: compressed air Which of the following components is a requirement on every air tank? a draincock What is the minimum total storage volume of air dedicated to brake system requirements of an air brake-equipped trailer? eight times total chamber volume The function of an air brake chamber is to: convert the energy of compressed air into mechanical force An air brake equipped truck is traveling on a highway at 60 mph and the driver makes a service brake application. Which of the following should be true in all of the spring brake chambers on the vehicle? Both the service and hold-off chambers are charged with air. Technician A says that automatic slack adjusters can improve brake balance and reduce downtime and maintenance costs. Technician B says that automatic slack adjusters should not be adjusted after installation. Who is correct? Technician A only When an inversion valve becomes functional during a brake failure, what force is used to brake the vehicle? spring pressure Which of the following determines the amount of leverage gained by a slack adjuster? the slack adjuster length Which of the following is an advantage of an open anchor brake shoe? faster brake jobs The brake shoes, retraction, and fastening hardware are mounted to: a spider In order for a service signal to pass through a TP valve, which of the following must be true? The trailer supply dash control valve must be on What actuates the relay piston in a foot valve on an air brake system when the valve is operating normally? air pressure Which of the following does the most to ensure that the driver has brake feel at the foot valve in a truck air brake system? metered primary circuit service pressure Which of the following best describes the term coefficient of friction? the aggressiveness of a friction material Technician A says that in a tractor/trailer B-train combination, the crack pressures of the relay valves over the pup axles would be the highest on the rig. Technician B says that quick-release valves on the service gladhands can speed up service brake release times on multitrailer combinations. Who is correct? Technician B only A trailer compliant with a spring brake priority system has no air in its on-board air tanks. When coupled to a tractor air supply, where is the air directed to first? the hold-off chambers