英文原文How Car Suspension WorkBy William HarrisUniversity of Michigan When people thinly of automobile performance, they normally think of horsepower, torque and zero-to-60 acceleration. But all of the power generated by a piston engine is useless if the drier cant control the car. Thats why automobile engineers turned their attention to the suspension system almost as soon as they had mastered the four-Stroke internal combustion engine. Double-wishbone suspension on Honda Accord 2005 Coupe 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 and to ensure the comfort of the passengers. In this article, well explore how car Suspensions work,how theyre evolved over the years and where the design of suspensions is headed in the future.1 .Vehicle Dynamics If a road were perfectly t1at, with no irregularities, suspensions wouldnt be necessary. But roads are far from t1at. Even freshly paved highways have subtle imperfections that can interact with the wheels of a car. Its these imperfections that apply forces to the wheels. According to Newtons laws of motion, all forces have both magnitude and direction. A bump in the road causes the wheel to move up and down perpendicular to the road surface. The magnitude, of course, depends on whether the wheel is Striking a giant bump or a tiny speck. Either way, the ca.r wheelexperiences a vertical acceleration as it passes over an imperfection. Without an intervening structure, all of wheels 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,wheels can slam back into the road surface. What you need is a system that 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 farces at work an a moving car is called vehicle dynamics, and you need to suspension is necessary of need to understand same of these concepts in order to appreciate why a necessary in the first place. Mast automobile engineers consider the moving car Pram two perspectives: 1) Ride-a cars ability to smooth out a bumpy road 2)Handling-a cars ability to safely accelerate, brake and corner These two characteristics can be further described in three important principles-road isolation, road holding and cornering. The table below describes these principles and how engineers attempt to solve the challenges unique to each.A cars suspension, with its various components, provides all of the Solutions described. 2. The Chassis System The suspension of a car is actually part of the chassis, which comprises all of the important systems located beneath the cars body.figure 2-1 ChassisThese systems include: 1) The frame-structural, load-carrying component that supports the cars engine and body, which are in turn supported by the suspension 2)The Suspension system-setup that supports weight, absorbs and dampens shock and helps maintain tire contact 3)The steering system-mechanism that enables the driver to guide and direct the vehicle 4) The tires and wheels-components that make vehicle motion possible by way of grip and/or friction with the road So the suspension is just one of the major systems in any vehicle. With this big-picture overview in mind, its time to look at the three fundamental components of any suspension: springs, dampers and anti-sway bars.3 .springs Todays springing systems are based on one of four basic design:1)Coil spring-This is the mast common type of spring and is, in essence, a heavy-duty torsion barcoiled around an axis. Coil springs compress and expand to absorb the motion of the wheels.2)Leaf spring-This type of spring consists of several layers of metal (calledleaves) bound together to act as a single unit. Leaf springs were first used on horse-drawn carriages and were found an most American automobiles until 1985.They are still used today on most trucks and heavy-duty vehicles.3)Torsion bars-Torsion bars use the twisting properties of a steel Gar to provide coil-spring-like performance. This is how they work: One end of a bar is anchored to the vehicle frame. The other end i5 attached to a wishbone, which acts like a lever that mares perpendicular to the torsion bar. When the wheel hits a bump, vertical motion is transferred to the wishbone and then, through the levering action, to the torsion bar.The torsion bar then twists along its axis to provide the spring farce. European caretakers used this system extensively, as did Packard and Chrysler in the UnitedStates, through the 1950s and 1960s.4)Air springs-Air Springs, which consist of a cylindrical chamber of air positioned between the wheel and the cars body, use the compres5ire qua