Spanner in the works

You'd have to have pretty big nuts for these! 
They were hanging up inside the Crofton Beam Engine pumping station in Wiltshire on our visit this afternoon. Fascinating place, it was built in 1807-9 to supply water to the highest point of the Kennet & Avon Canal, which links London and Bristol. Worth a visit. Just a shame it was out of action today due to technical difficulties