Abstract: An electric power supply operated switch clock comprises a housing with a synchronous motor in the housing which is adapted to drive a rotatable switch ring for timed rotary movement so as to cause riders positioned at selected one or ones of a plurality of switch rider receiving elements on the ring to engage and actuate a quick-break switchgear in the housing. The construction includes a plug head which is engaged on one end of the housing and a plug socket which is engaged on the other end with a pin bushing block being disposed therebetween. A synchronous motor mounted between the plug head and the plug socket is connected through a timing mechanism disposed around the pin bushing to drive the drive ring which is rotatable over a rib formed in a housing partition wall and on a socket cup which engages through the adjacent end wall.