Washer main role is to reduce the stress bearing surfaces, protect the connector surface, in order to prevent the connection may be loose pair of spring lock washer and multi-toothed lock washers, lock washers and nuts round saddle, waveforms, conical spring washers, flat washers are mainly used to reduce the pressure, when some parts of the tightening axial force is large, easy to press into the dish washer, then can switch to increase the hardness of the material and to resolve. Locking effect of the spring washer in general, important parts as little as possible with or without, and the use of self-locking structure. For tightening for high-speed (pneumatic or electric) spring washer, preferably gasket surface phosphate processing to improve its anti-friction properties, or easy to friction heat and burn or mouth, or even damaging the connector surface. For thin joints, spring washers structure should not be used. According to the statistics, spring washers in the car used less and less. Toothed spring washer in connection toothed locking force due to the large and uniform, used more in the automotive industry, and the spacing of the tooth less.