Bosch Washing Machine, the working principle of the touch-point snap-action switch. Data source: Beijing Bosch Washing Machine After-sales Service Telephone http://blog.tianya.cn/blogger/blog_main.asp?BlogID=3446026. The touch-point snap-action switch is a micro-power switch installed at the clothes inlet (i.e., the machine door) of the drum washing machine. It is connected in series in the power circuit and can control and protect the washing machine. When the machine door of the washing machine is closed properly, the door handle hook presses down the contact point of the door switch to connect the power supply of the washing machine. When the machine door of the washing machine is opened or not closed properly, the contact point of the door switch breaks off, cutting off the power supply of the washing machine. During the operation of the washing machine, if the machine door is opened, the door switch will act to cut off the power supply, making the washing machine stop running, thus ensuring the safety of the user. Beijing Bosch Washing Machine Repair Center.