View into left hand inside valve gear.(Just above front bogie).

On the left of the aperture is the inside left valve steamchest, taking its drive from the horizontal red/brown rod on the right. This rod derives its motion from a hidden radius rod and combination lever, working from a crank between the front pair of driving wheels.

Working inside the firebox.

Note the huge number of supporting stays that prevent the collapse of the inside wrapper of the firebox when the boiler is at full pressure. At 250 psi, each stay supports around a ton. Members of the team are shown removing them for replacement.

Setting the valves.

The complex measurements for setting the opening and closing of the four sets of valves began here. A measurement was taken off the valve ports on the left inside valve, and translated to an external rod as a reference point.

The reference rod.

The valve spindle.

A rod with moving collars was attached to the front of the valve and distances accurately set from the faces of the valve piston.

The valve being replaced inside the steamchest.

The valve in place.

Note this view of the rod that provides a fixed reference point for valve measurements.

This rod and collars is re-attached to the valve spindle.

As the valve was driven back and forth by turning the driving wheels, the valve port openings were indicated by the distances between the two pairs of end collars.

Another view of the whole device.

Taking measurements.

To turn the driving wheels.

After disconnecting the coupling rods to the back set of wheels, a set of rollers was introduced under the front and middle sets. These were turned with socket wrenches with long metal tubes to supply leverage, and an air pump between the middle set of wheels to assist. As weeks of valve setting went by, the wheels became significantly easier to turn.

The cab following removal of the roof.