机械丝杆式举升机一般是由一个电机驱动两个丝杆转动,两丝杆之间由链条传动,使举升臂上下移动,完成举升车辆动作。举升机的一个回路保护装置称为举升臂过行程保护,一般由安装于丝杆两端的行程开关K1、K2来完成(见图1)。一般举升机都有这种保护电路,它的主要作用是防止举升臂上下超过规定的行程,造成丝杆螺母的损坏。 Mechanical screw lift is generally driven by a motor two screw rotation, the two screws by the chain drive, so that the lifting arm up and down to complete the lifting vehicle movements. A circuit protection device for the lift is called lift arm over-travel protection, which is usually completed by the travel switches K1 and K2 mounted on both ends of the screw (see Figure 1). General lift have this protection circuit, its main role is to prevent the lifting arm from exceeding the provisions of the trip, causing screw nut damage.