Railway signal light colour filter - has circular frame U=shaped in section for firm grip on filter

摘要

A colour filter (1) for railway signals or the like is mounted in a circular frame (2). The latter is U-shaped in section, so that it grips the filter (1) securely. It can also be clamped around the filter (1) circumferentially by tightening a bolt through flanges (3) at the opening in the frame (2).