HOLE SENSING DEVICE FOR SPIKE DRIVER

摘要

A hole sensing device for spike driving machine is disclosed. The sensing device has two protecting fingers both of which ride along the surface of a tie plate as the sensing device is swept along parallel to the rails. The fingers actuate two switches one open and the other closed when the fingers are not contacting the tie plate. When the fingers are both engaging the tie plate the switch associated with the loading finger is open and the other closed. As soon as the loading finger registers with a hole it closes its associated switch completing the circuit and allowing a hole sensing signal to be sent.