air brakes

Question 1

the application pressure gage shows how much …..

Answer 1

air pressure is being applied to the tanks

Question 2

the spring brakes used on the chambers in a straight truck will bring you to a stop when air pressure drops below how many psi?

Answer 2

20psi

Question 3

what happens if your alcohol evaporator does not have enough alcohol?

Answer 3

ice may form in the air storage tank and cause a brake failure

Question 4

your truck or bus has a dual air brake system. if a low air pressure warning comes on for only one system what should you do?

Answer 4

bring your vehicle to a complete stop and see if the air pressure changes

Question 5

why drain water from compressed air tanks?

Answer 5

water freezes in low temp and can cause brakes to fail

Question 6

the safety valve is set automatically when pressure is

Answer 6

150 psi

Question 7

your truck has a dual air system and one of the system loose its pressure. what will happen?

Answer 7

either the back or front brake will not be fully operational

Question 8

what can parking or emergency brakes of trucks or busses be legally held by?

Answer 8

springs

Question 9

if your truck or bus has dual parking control valves you can use pressure from a separate tank to….

Answer 9

release the spring emergency/parking brakes to move a short distance

Question 10

if your truck has a properly finctioning dual air brake system and minimum size air tanks the air pressure should build up from 85 psi to 100 psi within how many seconds?

Answer 10

45

Question 11

how should you check that your service brakes are working properly?

Answer 11

park on level ground, wait until normal air pressure is reached, release the parking brake and move forward slowly at about 5 mph then apply the brakes firmly using the brake pedal

Question 12

a straight truck or bus should not leak more than how many psi per minutes if the engine is off and brakes are released?

Answer 12

2 psi

Question 13

during normal conditions spring brakes are usually held back by…..

Answer 13

air pressure

Question 14

the air compressor stops pumping air at what psi?

Answer 14

125psi

Question 15

the driver must be able to see a low air pressure warning which comes on before pressure in the service air tanks fall below how many psi?

Answer 15

60 psi

Question 16

excessive use of service brakes result in overheating which can lead to….

Answer 16

expansion of brake drums

Question 17

the most common type of foundation brake found on heavy vehicles is the….

Answer 17

s-cam drum

Question 18

if you must make an emergency stop you should brake so you…..

Answer 18

can steer and so your vehicle stays in a straight line

Question 19

your truck or bus has a dual air brake system. if a low pressure warning comes on for only one system what should you do?

Answer 19

stop right away and park. continue once the system is fixed

Question 20

if your vehicle has a an alcohol evaporator every day during cold weather you should….

Answer 20

check and fill the alcohol level

Question 21

the air loss for a straight engine OFF and the brakes ON should not be more than…..

Answer 21

3 psi per minute

Question 22

when does the low pressure warning come on ?

Answer 22

when the pressure in the service tanks falls below 60 psi

Question 23

the braking power of the spring brakes

Answer 23

depends on the service brakes being in adjustment

Question 24

the brake lag distance at 55 mph on dry pavement adds about how many feet?

Answer 24

32 feet

Question 25

why is the stopping distance for air brakes longer than for hydraulic brakes?

Answer 25

brake lag

Question 26

it is accepted that to much heat caused by using your brakes too often can also cause.....

Answer 26

brakes to fade or fail

Question 27

repeatedly partially releasing and pressing the brake pedal may result in....

Answer 27

the loss of brake air pressure

Question 28

what brake system applies and releases the brakes when the driver uses the brake pedal?

Answer 28

the service brakes

Question 29

when do the slack adjusters need to be adjusted?

Answer 29

when there is 1inch freeplay while pulling hard

Question 30

what psi is the air brake system fully charged at?

Answer 30

125

Question 31

what does your brake pedal control?

Answer 31

how much air pressure is being applied to the brakes

Question 32

what does the s cam do?

Answer 32

forces the brake shoes inside the drum

Question 33

under normal conditions in order to engage the parking brakes driver must.....

Answer 33

let the air out of the brake system

Question 34

all air brake equipped vehicles have....

Answer 34

A supply pressure gauge

Question 35

with air brake vehicles the parking brake should be used.....

Answer 35

whenever you leave the vehicle unattended

Question 36

if the spring brakes are on when should you push the brake pedal?

Answer 36

never

Question 37

to check free play of the manual adjusters of s cam brakes you should park on....

Answer 37

level ground chock the wheels and release the parking brake

Question 38

when brakes are applied what will the brake shoes press up against?

Answer 38

brake drum or disc

Question 39

if air pressure does not build up air in the correct amount of time then.....

Answer 39

your air pressure may drop to a low point while driving. requiring an emergency stop

Question 40

at what psi does the safety valve reduce pressure?

Answer 40

150

Question 41

what does the braking power of the spring brakes depend on?

Answer 41

service brakes being adjusted

Question 42

what does the air pressure governor control?

Answer 42

when air is pumped into the air tanks

Question 43

what does the stop light switch do?

Answer 43

turns on your brake lights to warn drivers behind you