Vehicle Ride

1. Usually the wheel rate is different from spring rate as vehicle when in a bump the load is transfered not directly transferd to the spring rather some energy is absorbed by the tyre and the system ,but wheel rate is always less than spring rate as the displacement ratio between wheel and spring.

2. Ride rate is change in vertical force on tire with suspension travel where as the wheel rate is vertical force per unit vertical displacement and it refers at wheel center so the displacements are different .

3. (i) The preferences of amount of damping changes for low and high frequency regions so we cannot use same amount of damping.

(ii) In compression the sping absorbs energy so lower damping is required as damped but in rebound its reverse it needs higher damping.

4. The ride frequency at rear is generally higher than that of rear inorder to make vehicle move in one phase .So, when the vehicle experinces a bump in order the rear will coupeup with front wheels immediately so the vehicle is stable.

5. (i) Higher unsprung mass is prefered so to ensure less vibrations.

(ii) lower damping is prefered as lower the damping lower is vibration is experinced.

6. The stiffness of air suspension being lower than that of the steel suspensions the factors such as ride rate and ride frequency remain low which results low frequencies with smoother rides ,in stand of ride frequency.

7. (i) Sprung mass natural frequency : 1.07 hz

(ii) unsprung mass natural frequency : 11.8 hz

8. (i) Time front < sum of time rear and lag in the first condition

(ii) Here the equation holds

so 2nd case holds for flat ride perspective.