section 5 air brakes Flashcards
what are the three different break systems of air breaks
Service breaks , parking breaks , and emergency breaks
What does the service breaks do
Applies and releases the breaks when you use the break pedal during normal driving
What do the parking breaks do
applies and releases the parking breaks when using the parking breaks control
What do the emergency breaks do
uses parts of the service and parking brake system to stop in a break system failure
what does the air compressor do
pumps air into the air storager tanks (Resovoir)
what does the air compressor governor do
Controls when the air compressor will pump air into the air storager tanks.
what turns the compressor on and off
the key
what are air storage tanks used for
Air storage tanks are used to hold compressed air
What happens when water catches in the compressed air
comrpressed air usually has some water and some oil in it which is bad for air breaks , water can freeze in cold weather and cause break failure
what should you do with air tanks manually at end of shift
you must drain the tank yourself at the end of each shift
What is the purpose of the alchohol evaporator
Puts alchohol into the system to help reduce ice in brake valves
Check achohol container as neccasary during cold weather
safety valve is installed in first tank the air compressor pumps air to
pushing down the brake pedal
pushing the pedal down harder than neccasary
foundation brakes are on every wheel most common being s cam drum brake q
brake fade
too much heat can cause the brakes to stop working
when you push the brake pedak air is let out into each
Do you need a pressure gauge?
all vehicles with air brakes must have a pressure gauge connected to air tank
what does the application pressure gauge do
shows how much air pressure you are applying to brakes
20 -45 psi
when emergency brakes apply
55pi
alarm sounds before pressure falls to dangerously low
100pi
governor cuts in normal pressure
125 pi
governor cuts out full pressure
150 psi
the safety valve releases air from tanks
wig wag warning
warning for when psi is under 55
stop light switch
the air brakes system warns drivers behind you when you put on the breaks
front brake limiting valve when put on slippery reduces stopping power by how much
1/2
when to use front brake limiting valve
never use front brake limiting valve
what are emergency breaks and parking breaks held on by
mechanical spring pressure
what holds springs together
Air pressure
when will spring breaks fully come on automatically
spring breaks will come on fully when psi drops from range of 20-45psi
what does the braking power of the spring brake depend on
the brakes being adjusted proper
what does parking brakes look like and color
In newer vehicles with air brakes you put on the parking brake using a diamond shaped yellow push pull control knob
what is compounding the brakes
never push down on the air brakes when springs are active or you’ll end up compounding brakes
dual parking control valves
when main air pressure is lost, the spring breaks come on ,some vehicles like buses have a separate air tank for emergency
what stops air from escaping the air tank
The one way check valve
what is the wet tank
first tank the first one
min psi for primary and secondary system
100psi
what to do if low air pressure drops below 55
safely stop and park vehicle have air brake system fixed
during step 5 of walk though inspection
check slack adjusters on s-cam , park on level ground , release parking brakes to adjust slackers
how long can a crack not be on brake drums
half the width of the friction area
