These are the cog wheels that powered Selby swing bridge from 1792 until their removal in 1970. The swing bridge was the first in the world to make widespread use of ball bearings to allow rapid opening. The 31'span could be opened by turning a handle to operate these cogs in under a minute.At the time of closure, the bridge was the largest wooden swing bridge in Europe.
A bridge was vital as routes of communication were interrupted by the River Ouse winding across the West and East Ridings of Yorkshire.
The opening of the swing bridge enabled Selby to become the "Port of the West Riding", despite being 65 miles from the sea! Improved communication heralded 50 years of great prosperity.
They hint at a social history as youth of the town could earn a half crown by relieving the men of their job and taking a turn winding the wheels to let the ships by.
Their design in cast iron also tells of the technology of their time in that human strength had to overcome natural obstructions. In 1792 these wheels were mighty objects of wonder:their replacement in 1970 was by a mundane electric motor. That which was once achieved by the toil of man is now carried out at the press of a button.