Canal bridge

This is a twin-leaf bascule bridge on the Forth and Clyde canal at Port Dundas.

I was looking at this bridge today and realising it really was a thing of some beauty and engineering elegance.

The bridge lifts by attaching a crank handle to the centre of the small cog in the photo. This in turn drive the larger cog which drives the cog you see at the bottom - then through a series of cogs, a large 1/2 moon cog lifts one side of the bridge - you can see this big cog at the same mechanism in the middle of the photo at the other side of the canal. Once lifted, the central small cog has a brake handle which you can see if you look close at this picture, which snaps into the cog to keep the bridge open.

Fascinating!