Abstract: An improved limit switch mechanism is provided in which it includes a plurality of cassettes of limit switch subassembly, each cassette containing: a limit switch mounting bracket, a first limit switch and a second limit switch fastened onto said limit switch mounting bracket by screws; the deflection direction of the control lever of each limit switch being directed radially towards the center of the concerned switch actuator when each cassette of limit switch subassembly is inserted and fixed in a pair of slits, which is inclined at certain angle relative to horizontal direction and provided on opposite side walls of the base frame. Accordingly, positive actuation on control lever of each limit switch and long service life of each limit switch can be achieved.