Mellor signal head pin

A traffic light signal head hinge pin, designed by industrial designer David Mellor in 1965, on commission from the Ministry of Transport (see AIBDC : 009358.1). The individual lights were encased within a blow moulded unit in polypropylene (PP), the bulbs accessible from the front via a hinged opening secured by PP pins. This spare was made by Plessey Automation for Somerset County Council and was gifted to the museum by Yunex Traffic who supply, install and maintain traffic signal and control equipment for the BCP council. Although the Mellor signal head was widely used throughout the UK during the 1960s-1990s, engineers found the design problematic for maintenance: eg. the hinge pins were often difficult to remove, resulting in breakage, and were easily dropped onto the ground and then lost; the transformer unit was positioned behind the light within the main signal head unit which had to be unscrewed. These issues were addressed in subsequent designs such as the Siemens Helios signal head (see AIBDC : 009359) which incorporated all the internal componentry within one box that opened via two sliding clips at the front, thereby simplifying the process of installation and fault repair.

AIBDC : 009358.2