Photoelectric apparatus for railroad surveying

摘要

1,014,323. Indicating condition of rail tracks. CANADA IRON FOUNDRIES Ltd. June 7, 1962 [June 30, 1961], No. 22094/62. Heading B7N. [Also in'Division G1] A system for railroad surveying comprises a light transmitter mounted for movement along a railway track, a light beam receiver similarly mounted, an opaque board mounted for movement along the track between the transmitter and the receiver adjacent the receiver, means responsive to beam reception to indicate low parts of the track surface, the said light beam receiver including a parabolic reflector having a photo-electric cell at its focal point masking means to mask off between at least one-fifth of the upper part of the reflector when the reflector is oriented to receive the transmitted beam. In the embodiment shown, a transmitter 10, Fig. 1, mounted on a wheeled frame 10a at a distance along the track to be surveyed of the order of 150 feet from the opaque shadow board 14 mounted on a wheeled frame 14a transmits a light beam such as an infra-red beam, above the track towards the receiver 12 also mounted on a wheeled frame 15a or a tamping machine, the wheeled frame 14a of the board 14 being attached at a distance of the order of 15 feet from the frame or tamping machine 15a. The receiver 12 comprises a hood 13 and a parabolic reflector 17, Fig. 2, with its photo-electric cell 18 and between the hood 13 and the reflector are secured a fresnel lens, a filter 16 and a masking disc 20. When on a level track, the board 14 and the mask 20 are so aligned as to prevent the beam from reaching the photo-electric cell 18 but if the board 14 travels over a low section of track its top edge drops below the masked portion 21 of the masking disc 20 allowing an appreciable amount of light to reach the photoelectric cell 18, the output of which is fed to an amplifier (Fig. 3, not shown) and utilized to light a warning lamp. Instead of using the mask 20 an equivalent portion (Fig. 4, not shown) of the reflector 17 may be made non-reflecting.