Air System Fundamentals

Question 0

True of false. The greater coefficient number of friction, the more friction, there for the more stopping power.

Answer 0

True

Question 1

What does C.O.F stand for? And what does it mean?

Answer 1

COF stands for the coefficient of fraction. It is the force required to move one body that is in contact with another body.

Question 2

To stop a vehicle that has the weight doubled what must you do to the stopping power?

Answer 2

You must double the stopping power.

Question 3

If speed is doubled how much should stopping power be multiplied by?

Answer 3

2x2=4 times

Question 4

If weight and speed are both doubled how much should stopping power be multiplied by?

Answer 4

2 x 4 = 8 times
2 = weight
4 = speed

Question 5

What is stopping time measured by?

Answer 5

Stoping time is measured from the time the driver applies the brakes to the time the vehicle comes to a complete stop.

Question 6

What is the average operators reaction time in a unit of seconds?

Answer 6

0.7 seconds depending on age, fatigue, drugs/alcohol, illness.

Question 7

What is lag time?

Answer 7

The time taken for air to flow through the system and apply the brakes.

Question 8

What is one advantage and disadvantage of air brakes over hydraulic brakes?

Answer 8

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.

Question 9

What happens when a gas is compressed to half it’s volume?

Answer 9

The volume decreases by half and the pressure will double and the temperature will double.

Question 10

What are foundation brakes?

Answer 10

Foundation brakes is the actual brakes applying.

Question 11

Hoe do you find the area of a spring brake diaphragm?

Answer 11

A= 3.14 squared.

Question 12

What happens to braking force developed when the brake chamber and diaphragm is increased?

Answer 12

The breaking power goes up.

Question 13

What formula do you use to calculate brake chamber force?

Answer 13

F= A X P

A= area in in squared or m squared 
P= pressure in psi or kpa

Question 14

What is the formula for torque?

Answer 14

T= F X L
Force
Length of slack adjuster.

Question 15

What is brake fade?

Answer 15

When you loose your COF because of temperature of your brakes causing them to glaze over and you have no brakes then.

Question 16

What can change the amount of friction?

Answer 16

• type of brake material used
• condition of materials ex. Warping, glazing, oil
• force applied
• the temp of lining or drum

Question 17

Name three factors of stopping time.

Answer 17

Reaction time 0.7
Lag
Stopping distance

Question 18

Name the three compressed air brake advantages.

Answer 18

1. They can accept some degree on leakage
2. The components are compact, light and inexpensive.
3. THEY DO NOT REQUIRE BLEEDING

Question 19

Name the two disadvantages of air brakes.

Answer 19

1. There is a certain amount of lag time

2. They are more susceptible to contamination.

Question 20

What is the normal pressure applied at the petal to the system in psi?

Answer 20

0 to 40 psi.

Question 21

What is the function of the compressor?

Answer 21

To compress air to feed to the system.

Question 22

What is the function of the governor?

Answer 22

To cut out when full system air pressure has been reached.