Cdl air brakes

the brake drums or disc
Click the card to flip 👆
1 / 47
Terms in this set (47)
the brake drums or disc
must not have any cracks longer than half the width of the friction area
a straight truck or bus air brake system should not leak at a rate of more than _ psi per minute with the engine off and the brakes released
2
to check the air compressor governor "cut in" and "cut out" pressures:
-run the engine at a fast idle
-step on and off the brake to reduce tank pressure
-monitor the air pressure gauge
the air compressor governor controls:
when the air compressor pumps air into the storage tanks
the governor allows the air to start pumping again when it reaches the cut in level, or around:
100 psi
modern air brake systems combines three different systems. they are the service brakes, the parking brakes and the:
emergency brakes
when you apply pressure to the brake pedal, you are:
pushing against a spring and against air pressure to the brakes
what can legally hold a parking or emergency brake in position for a truck, truck tractor, or bus?
spring pressure
you should know that your brakes are fading when:
you have to push harder on the brake pedal to control your speed on a downgrade.
if your air compressor stops working:
you'll still have air pressure left in the air tanks.
stab braking occurs when you-press on the brake pedal as hard as you can -release brakes when the wheels lock up -apply brakes when wheels start rollingthe braking power of the spring brakesdepends on the adjustment of the service brakesof the choices below, the first thing to do when a low air pressure air warning comes on isstop and safety park as soon as possiblesome air brake systems have an alcohol evaporator which helpsreduce the risk of ice in the air brake valves during cold weathercompressed air is storedin the storage tankair braking takes more time than hydraulic braking because air brakesneed to have airflow through the lines to workto check the slack adjusters on the S cam brakes, you shouldwear gloves and pull hard on each slack adjusteryou should avoid using the parking brakewhen the brakes are hotin air brakes vehicle, the parking brake should be usedwhenever the vehicle is parkedslack adjusterscan be adjusted manually or automaticallyvehicles with air brakes must havean air pressure to show the pressure available for brakingfanning air brakesdecrease the air pressureduring normal driving, spring brakes are usually held back byair pressurethe service brake systemapplies and release the brakes by using the brake pedal under normal drivingsafety valve in the air compressor tank is set to open at150 psioil and water usually collect in comprised air tanks. if you do not have an automatic tank drain, when should you drain the air tanks?after every working dayan air tank is equipped with a drain valve to removewater and oilair tanks should be drained-at the end of each day or shift -to keep sludge from clogging brake system valves -manually when automatic devices failif the air compressor should develop a leak, what keeps the air in the tanks?the one way check valvean emergency brake:-is required on commercial vehicles -must be held on by mechanical force -could be activated by the loss of air pressureto test the low pressure warning signs, you should do all BUT the following:ask a friend to listen for the signalyou should avoid using the parking brake:when the brakes are hotwhen driving down a long steep hill, you should:release the brake when you are 5 mph below your safe speed.to test air brake leakage rates you shouldturn off engine and release the service brakewhen the safety valve releases air it means that-the pressure has exceeded 150 psi -too much air is in the air compressor -something is wrong, and you should have it checked by a mechanicall vehicles with air brakes are required to have a low pressure warning signal. this could be:-a red light -a wig wag mechanical arm -a buzzerair pressure equipped vehicles must have:a supply pressure gaugeto test your service brakes you should:release the parking brake, move forward slowly and depress brakesthe brake system that applies and releases the brakes when the driverservice brake systemair braking takes more time than hydraulic braking because air brakes:need to have airflow through the lines to workwhich of the following makes the totally stopping distance for air brakes longer than that hydraulic brakesbrake leg distancethe application pressure gauge shows the driver how much pressure:is being applied to the brakes.the vehicle single brakes system needs adjustment ifthe compressor cuts between 70 to 90 psibraking power of spring brakesdepends on the adjustment of the service brakesa combination vehicle air brake system should not lose air faster than3 psi per minutewhich type of brake is the most common in commercial vehicles cam brakes