AIR BRAKES Flashcards
During normal driving, spring brakes are usually held back by:
Air Pressure
The brake pedal in an air brake system:
controls the air pressure applied to put on the brakes
The brake system that applies and releases the brakes when the driver uses the brake pedal is what system?
service system
All air braked equipped vehicles must have what?
a supply pressure gage
If your truck or bus has a dual parking control valve, you can use pressure from another tank to:
release the spring brakes to move the vehicle in an emergency
The most common type of foundation brake found on heavy vehicles is the:
s-cam drum brake
Parking or emergency brakes of trucks and buses can be legally held on by what?
spring pressure
If your vehicle has an alcohol evaporator, it is there to:
reduce the risk of ice in valves and other parts in cold weather
Some air brake systems have an alcohol evaporator. What might happen if you don’t keep the unit filled with alcohol?
ice may form in the tank and cause brakes to fail
The most important thing to do when the low air pressure warning comes on is
stop and park safely ASAP
The driver must be able to see a low air pressure warning that must come on before pressure in the tanks fall below what?
60 psi
Under normal conditions, in order to engage the parking brake the driver must first:
let the air out of the system
To check the free play of manual slack adjustors on s-cam brakes, you should park on:
level ground, chock the wheels, and release the parking brakes
If your vehicle has an alcohol evaporator, every day during cold weather you should:
check and fill the alcohol level
For air brake systems in good condition, the air compressor should start pumping at what psi?
100 psi
A straight truck or bus system should not leak at a rate of more than _ psi per minute with the ENGINE OFF and the BRAKES RELEASED?
2 psi
A slack adjustor probably needs adjustment if it moves more that _ when you pull on it.
1 inch
If you are driving down a steep downgrade and you have reached your safe speed of 40 mph, you should apply the service brakes until your speed reaches what?
35 MPH
The use of brakes on a long and/or steep downgrade is only a supplement to:
the braking effect of the engine
Under ideal conditions, a truck with air brakes going 55 mph would require a stopping distance of what?
more than 300 feet
Emergency stab braking is when you
brake as hard as you can, release the brakes when the wheels lock, and apply the brakes again when the wheels roll
The braking power of the spring brakes
depends on the service brakes being in adjustments
If you must make an emergency stop you should brake so you
can keep your vehicle in a straight line and turn if it becomes necessary
The proper method of braking when going downhill is to reduce your speed by _ MPH below your safe speed before releasing brakes
5 MPH
