The shutter operating levers protruding through the header tank.
'O' is the offside lever connected to the offside centre shutter.
'N' is the nearside lever.
'L' is the lower link.
'U' is the upper link.
'L' and 'U' are hinged on lever 'O' and, when aligned properly, form the pivot for the dog bone links onto lever 'N'.
On the left is the pin for connecting the Calorstat arm.
The bolt on the right forms the pivot for the dog bones.
The two dog bones and their axle link the two shutter operating levers together - see below.
Photographed prior to painting in order to achieve some sort of contrast - I am fed up with trying to get good shots of black objects against a black background.
The dog bones can be seen clamping the nearside lever whilst being clamped by that of the offside. All of these connections are supposed to pivot - so make sure that they do not get gummed up with paint or rust.