Point detection and indication with latch out means

Abstract

There is provided an electric motor driven switch machine for positioning a railroad track at a switching point having rail point detection and indication mechanism. In particular, the detection and indication mechanism has a latch out mechanism that identifies a latch out condition when the railroad tracks are not at, or near, their proper positions before or after switching the railroad tracks. The detection and indication mechanism includes a four bar linkage which comprises a point detector bar, two cam followers, and a link arm assembly. The cam followers, supported in part by the link arm assembly, are connected to two point detector switches, so that the switch machine is operating when either one of these switches is closed or the railroad tracks are being switched. The latch out mechanism, located on the link arm assembly, may produce and indicate a latch out condition, thereby causing the two point detector switches to be held open until the railroad tracks are switched again from a remote location or at the switch machine. Optionally, a latch out switch may be added to the detection and indication mechanism in order to sustain the latch out condition and prevent the railroad tracks from being switched from a remote location until a safe condition is restored manually at the switch machine.