Vehicle Ride

1. It is because of the position of the spring. springs are generally positioned at some distance from the wheel. This generates mechanical advantage also called as insrtallation ratio, hence displacement at the wheel is generally different than displacement at the spring so wheel rate and spring rate are generally different.

2. Ride rate is vertical force per unit displacement of tires ground contact reference point relative to the chassis, where as wheel rate is same but meausured at the wheel center. Ride rate consideres the stiffness of tires hence its value is less than wheel rate. For infinitely stiff tires both will be almost same, but otherwise they will not be.

3.

a. No, same damping can not be used for low and high frequency range because we need high damping in low frequency region and low damping in high frequency range.

b. No, because during compression spring stores the energy hence less damping required but in rebound there is nothing to save energy hence damping need to be higher to control the energy.

4. To get a flat ride, when front wheel hits the bump first and rear wheel hits later because of wheelbase distance, hence rear wheel needs to oscilate faster and need to be in phase with front wheel, hence rear wheel frequency needs to be higher.

5. For improved isolation in wheel hop region.

a. In wheel hop region lower unsprung mass degrades the isolation hence high unspring mass.

b. Low damping in wheel hop region.

6. Most important aspect of air suspension is its ability of instantaneous tuning. hence suspension characteristics can be adjusted as per the vehicle condition. In heavy vehicles in which sprung mass changes drastically suspension parameters can be adjusted instantaneously with the help of air suspension and better ride can be obtained in both empty and heavy load conditions.

7.

a. sprung mass natural freq = 1.072 Hz

b. Unsprung mass natural freq = 11.8.30 Hz

8. In zip file