05 The Friction Circle and Skid Control

Question 1

If a vehicle experiences a g-force which is greater than the amount of grip between the tires and the road surface, but less than the rollover threshold of the vehicle, the vehicle will start to skid before it rolls over.

Question 2

Best way to burn off vehicles kinetic energy and bring the vehicle to a safe stop?

Answer 2

Using the brakes

Question 3

Best method for preventing skid in a longitudinal direction?

Answer 3

Smooth braking and acceleration

Question 4

The amount of friction a road will provide depends on:

Answer 4

1. Weather conditions
2. Slope of road
3. Condition of tires

Question 5

Friction can be used to do:

Answer 5

1. Decelerate and stop the vehicle
2. Accelerate and drive the vehicle forward
3. Turn the vehicle in one direction or the other
4. Any combo

Question 6

Longitudinal friction

Answer 6

Braking and accelerating capabilities of the tires

Question 7

Lateral friction

Answer 7

cornering ability of the tires

Question 8

The amount of friction available for the fire apparatus operator to use is equal to the drag factor (stickiness) of the roadway. Therefore, the radius of our friction circle will be equal to the drag factor of the road.

Question 9

If front tires of a vehicle start to break traction while rounding a curve the vehicle will…

Answer 9

Under steer (vehicle will lose steering control and will travel in a straight line)

Question 10

Rounding a corner too fast will cause an…

Answer 10

Over steer (rear tires break traction and vehicle starts to spin

Question 11

Factors determining an under or over steer:

Answer 11

1. Weight distribution
2. Weight shift
3. Suspension geometry
4. Brake adjustments
5. Tire stiffness
6. Tire pressures

Question 12

Which is more dangerous, oversteer or understeer?

Answer 12

Over steer. (Vehicle becomes unstable in an oversteer)

Question 13

The key to preventing a skid:

Answer 13

Slow down and not skid in the first place.