【正文】 he coping generally a little farther.Above the gas wreath, a narrow insulating slot is usually set to cut off the heat flow which is spread from the piston coping to the first gas wreath and make parts of calories from a piston wreath spread, thus easing the hot burden of the first gas wreath. On some engines small wreathe slots are often made between the coping head and the first gas wreathe, sometimes till a few more wreath. This kind of small wreath can adsorb the lubricant because it accumulates the carbon. It can keep piston and the air cylinder walls from biting to match when it work in the condition of losing oil, so it is called accumulating the carbon slot.The calories that the piston coping absorbs also mainly passes the air cylinder wall through the piston wreath to leak proof department, again spread by the cool a word, the function of the piston head is in addition to install the piston wreath, still seal pletely function and transmit heat function, sealing pletely the air cylinder together with the piston wreath, keeping bustible admixture spirit from leak crankcase, at the same time pass the(7080)%calories to the air cylinder wall through the piston wreath.3. Piston skirt departmentThe piston skirt department refers to the parts from the bottom of the oil wreathe slot. It includes the pin which is used to pack the piston. The piston skirt department exercises to rise to lead to the function to the piston in the back and forth in the air cylinder, and bear the side pressure. The length of the skirt department is decided by the size and the piston diameter of the side pressure. The socalled side pressure mean in the pression route of travel and make route of travel of efficacy .The level ponent of the gas pressure which take effect on the piston coping presses the piston to the air cylinder wall. Compress the route of travel and make the side pressure direction of the efficacy route of travel air exactly the opposite, because of the bustion pressure consumedly high in press the pressure, so, make the side in the route of travel of efficacy pressure also consumedly high in press the side in the route of travel on the sides that bear the side pressure of the piston skirt department be called to push the dint to face, they be placed in to sell the mutually perpendicular direction of the stalk line with piston up.Drive LinesThe drive line includes all the parts from the and final drive carry the torque from the engine, the other. This fluid pressure takes over some of the effort needed to steer the vehicle.The steering column in the modern vehicle has many parts. It is designed to collapse or fold in a vehicle collision to protect the driver. In some installations, it may be tilted and telescoped to adjust the position of the steering wheel for the fort of the driver. To reduce the chance of theft, it also has a steering gear lock. On many vehicles, it has a transmission lock. Because it is within easy reach of the driver, the steering column may carry the transmission shift control lever, turn signal switch, headlight and dimmer switches, wiper switch, emergency flasher switch, and speed control.Brake SystemsService brakes must be able to stop the vehicle, prevent excess speed when coasting, and hold the vehicle in position while it is stopped on grades. They are designed so the driver can adjust the braking effort to maintain vehicle control. Vehicle control is influenced by brakes as well as the suspension and steering systems. Faults in the brake system can lead to wheel pull during braking. To repair suspension systems, parts of the brake system may require disassembly. Disc brakes have discs that rotate with the wheel . The brake disc is usually called a brake rotor. A hydraulically operated piston in a stationary caliper is used to force the lining of the brake pad against the braking surface of the rotor. The friction between the lining and rotor is used to slow or stop wheel rotation. The stationary caliper housing keeps the pads from rotating when they are being forced against the rotating brake disc.Disc brake pads move perpendicular to the face of the brake rotor. In this way, They are monly found on vans and trucks.Suspension systems have been changed and refined as the passenger automobile has developed. Design objectives differ between luxury sedans, performance vehicles, small pact vehicles, and light trucks. Tire improvements, along with improvements in shock absorbers, steering systems, and suspension control devices, have continually upgraded vehicle handling characteristics.Tiretoroad contact is needed for safe, positive vehicle control under all operating conditions. Keep in mind that all four tires must stay in contact with the road at all times for maximum vehicle control. Compromises are made in handling response, tire wear, driver fort, and ride harshness to achieve positive vehicle control.Suspension systems are divided into front suspension and rear suspension.Front suspension designs have developed from relatively rugged solidaxle designs to the modern lightweight, highstrength , struttype independent designs.