【正文】 ll look at some of the mon types of front and back suspensions typically used on mainstream cars. Front Suspension Dependent SystemsDependent front suspensions have a rigid front axle that connects the front wheels. Basically, this looks like a solid bar under the front of the car, kept in place by leaf springs and shock absorbers. Common on trucks, dependent front suspensions haven39。s ability to grip the road, as well as handling and braking BarsAntisway bars (also known as antiroll bars) are used along with shock absorbers or struts to give a moving automobile additional stability. An antisway bar is a metal rod that spans the entire axle and effectively joins each side of the suspension together. When the suspension at one wheel moves up and down, the antisway bar transfers movement to the other wheel. This creates a more level ride and reduces vehicle sway. In particular, it bats the roll of a car on its suspension as it corners. For this reason, almost all cars today are fitted with antisway bars as standard equipment, although if they39。s unsprung weight, while extension controls the heavier, sprung weight. All modern shock absorbers are velocitysensitive the faster the suspension moves, the more resistance the shock absorber provides. This enables shocks to adjust to road conditions and to control all of the unwanted motions that can occur in a moving vehicle, including bounce, sway, brake dive and acceleration squat. Dampers: Struts and Antisway BarsAnother mon dampening structure is the strut basically a shock absorber mounted inside a coil spring. Struts perform two jobs: They provide a dampening function like shock absorbers, and they provide structural support for the vehicle suspension. That means struts deliver a bit more than shock absorbers, which don39。t provide a perfectly smooth ride. Why? Because springs are great at absorbing energy, but not so good at dissipating it. Other structures, known as dampers, are required to do this.Dampers: Shock AbsorbersUnless a dampening structure is present, a car spring will extend and release the energy it absorbs from a bump at an uncontrolled rate. The spring will continue to bounce at its natural frequency until all of the energy originally put into it is used up. A suspension built on springs alone would make for an extremely bouncy ride and, depending on the terrain, an uncontrollable car. Enter the shock absorber, or snubber, a device that controls unwanted spring motion through a process known as dampening. Shock absorbers slow down and reduce the magnitude of vibratory motions by turning the kinetic energy of suspension movement into heat energy that can be dissipated through hydraulic fluid. To understand how this works, it39。 they were replaced with moldedrubber air springs in the 1930s. Photo courtesy HSW ShopperAir springsBased on where springs are located on a car ., between the wheels and the frame engineers often find it convenient to talk about the sprung mass and the unsprung mass. Springs: Sprung and Unsprung MassThe sprung mass is the mass of the vehicle supported on the springs, while the unsprung mass is loosely defined as the mass between the road and the suspension springs. The stiffness of the springs affects how the sprung mass responds while the car is being driven. Loosely sprung cars, such as luxury cars (think Lincoln Town Car), can swallow bumps and provide a supersmooth ride。 Air springs Air springs, which consist of a cylindrical chamber of air positioned between the wheel and the car39。 Leaf springs This type of spring consists of several layers of metal (called leaves) bound together to act as a single unit. Leaf springs were first used on horsedrawn carriages and were found on most American automobiles until 1985. They are still used today on most trucks and heavyduty vehicles. s time to look at the three fundamental ponents of any suspension: springs, dampers and antisway bars. SpringsToday39。 The steering system mechanism that enables the driver to guide and direct the vehicle s engine and body, which are in turn supported by the suspension s body. ChassisThese systems include: s suspension, with its various ponents, provides all of the solutions described. Let39。s grip on the road.CorneringThe ability of a vehicle to travel a curved pathMinimize body roll, which occurs as centrifugal force pushes outward on a car39。s ability to absorb or isolate road shock from the passenger partmentAllow the vehicle body to ride undisturbed while traveling over rough roads.Absorb energy from road bumps and dissipate it without causing undue oscillation in the vehicle.Road HoldingThe degree to which a car maintains contact with the road surface in various types of directional changes and in a straight line (Example: The weight of a car will shift from the rear tires to the front tires during braking. Because the nose of the car dips toward the road, this type of motion is known as dive. The opposite effect squat occurs during acceleration, which shifts the weight of the car from the front tires to the back.)Keep the tires in contact with the ground, because it is the friction between the tires and the road that affects a vehicle39。 Handling a car39。 Ride a car39。s 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 car wheel experiences a vertical acceleration as it passes over an imperfection. Without an intervening structure, all of wheel39。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. It39。ll explore how car suspensions work, how they39。t control the car. That39。在論文的寫作過程中，我得到了劉軍、樊聰?shù)韧瑢W的幫助，得