The difference between saddle spring washer and flat gasket. Spring gasket for anti-loosening, but the flat gasket is no relaxation function, and the flat gasket is only to increase the contact area, the spring washer can be anti-loosening, such as the motor and the base of the bolt generally to add a spring pad, because the motor vibration, if there is no spring pad, the nut will loosen the spring pad is mainly used for anti-loosening, for vibration is not big.