When people think of automobile performance, they normally think of horsepower, torque, and 0-60 acceleration. But all of the power generated by a piston engine is useless if the driver can't control the car. That's why automobile engineers turned their attention to the suspension system almost as soon as they had mastered the four-stroke internal combustion engine.
The job of a car suspension is:
- to maximize the friction between the tires and the road surface
- to provide steering stability with good handling
- to ensure the comfort of the passengers
• If a road were perfectly flat, with no irregularities, suspensions wouldn't be necessary. But roads are far from flat. Even freshly-paved highways have subtle imperfections that can interact with the wheels of a car. It's these imperfections that apply forces to the wheels
that result in wheel acceleration.
Without an intervening structure, all of wheel's vertical energy is transferred to the frame, which moves in the same direction. In such a situation, the wheels can lose contact with the road completely. Then, under the downward force of gravity, the wheels can slam back
into the road surface.
• What you need is a system that will absorb the energy of the vertically-accelerated wheel, allowing the frame and body to ride undisturbed while the wheels follow bumps in the road.
The study of the forces at work on a moving car is called vehicle dynamics. Most automobile engineers consider the dynamics of a moving car from two perspectives:
- Ride - a car's ability to smooth out a bumpy road
- Handling - a car's ability to safely accelerate, brake, and corner
• These two characteristics can be further described in three important principles:
- road isolation
- road holding