Air System Fundamentals Flashcards
True of false. The greater coefficient number of friction, the more friction, there for the more stopping power.
True
What does C.O.F stand for? And what does it mean?
COF stands for the coefficient of fraction. It is the force required to move one body that is in contact with another body.
To stop a vehicle that has the weight doubled what must you do to the stopping power?
You must double the stopping power.
If speed is doubled how much should stopping power be multiplied by?
2x2=4 times
If weight and speed are both doubled how much should stopping power be multiplied by?
2 x 4 = 8 times
2 = weight
4 = speed
What is stopping time measured by?
Stoping time is measured from the time the driver applies the brakes to the time the vehicle comes to a complete stop.
What is the average operators reaction time in a unit of seconds?
0.7 seconds depending on age, fatigue, drugs/alcohol, illness.
What is lag time?
The time taken for air to flow through the system and apply the brakes.
What is one advantage and disadvantage of air brakes over hydraulic brakes?
One advantage is that you don’t have to bleed air brakes.
One disadvantage is that air brakes have a greater lag time and possibly some contamination in the system.
What happens when a gas is compressed to half it’s volume?
The volume decreases by half and the pressure will double and the temperature will double.
What are foundation brakes?
Foundation brakes is the actual brakes applying.
Hoe do you find the area of a spring brake diaphragm?
A= 3.14 squared.
What happens to braking force developed when the brake chamber and diaphragm is increased?
The breaking power goes up.
What formula do you use to calculate brake chamber force?
F= A X P
A= area in in squared or m squared P= pressure in psi or kpa
What is the formula for torque?
T= F X L
Force
Length of slack adjuster.
What is brake fade?
When you loose your COF because of temperature of your brakes causing them to glaze over and you have no brakes then.
What can change the amount of friction?
- type of brake material used
- condition of materials ex. Warping, glazing, oil
- force applied
- the temp of lining or drum
Name three factors of stopping time.
Reaction time 0.7
Lag
Stopping distance
Name the three compressed air brake advantages.
- They can accept some degree on leakage
- The components are compact, light and inexpensive.
- THEY DO NOT REQUIRE BLEEDING
Name the two disadvantages of air brakes.
- There is a certain amount of lag time
2. They are more susceptible to contamination.
What is the normal pressure applied at the petal to the system in psi?
0 to 40 psi.
What is the function of the compressor?
To compress air to feed to the system.
What is the function of the governor?
To cut out when full system air pressure has been reached.
