Rail obstruction sensing means for a rail transportation system

In a rail transportation system including a vehicle adapted for travel along a track comprising at least one elongated rail, said vehicle having a speed control mechanism for controlling the speed thereof, a sensing assembly for detecting an obstruction on the rail which would inhibit continued and uninterrupted travel of the vehicle, said assembly including a housing mountable on the vehicle, a contact sensor element movable along and parallel to the rail, an elongated flexible cable interconnecting said housing and said sensor element for maintaining said sensor element at a predetermined distance from said housing depending on the speed of the vehicle, reel means rotatably mounted on said housing on which said cable is reeled for varying the length thereof, said reel means being capable of rewinding said cable upon its being slackened, means for propelling said sensor element along the rail for tensioning said cable at said predetermined distance, and said reel means being operatively connected to the speed control mechanism of the vehicle for decelerating vehicle speed to a complete stop if necessary as said cable becomes slackened upon the retardation of the travel thereof as it contacts a rail obstruction.