On Kings, Castles and Stars, the Walschaerts
valve gear is concealed between the frames, and driven off the front set of
driving wheels. The two inner valves, directly above the inner pistons, are
driven directly from these sets of valve gear. The outer valves, directly above
the outer pistons, take a reflected drive from the inner valve gear via a pair
of rocker arms emerging from the frames above the front bogie. Like the Stars
and Castles, no external valve gear is visible, but this aesthetically pleasing
arrangement makes for a maintenance nightmare, with over 120 oiling points, many
hard to reach, before the engine can take to the road.
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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. |
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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. |
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The reference rod.
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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. |
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The valve being replaced inside the steamchest.
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The valve in place.
Note this view of the rod that provides a fixed reference point for valve measurements. |
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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. |
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Another view of the whole device.
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Taking measurements.
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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. |
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Long exposure shot (8sec) to show wheels being inched round.
The turning of the wheels activates the movement of the valve spindles and pistons (the other way round from when the loco is in steam), and allows accurate measurements to be taken. |
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View from the side of the engine of the right hand inner valve, connected and adjusted.
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The right hand outer valve (top) actuated by a rocker arm off the inner right valve.
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The right rocker itself, connected and adjusted.
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From above the engine without the boiler in place.
The two piston cranks are visible, but between them are the slimmer eccentrics that drive the Walschaerts valve gear. |
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Underside view of the inner pistons and valves.
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Outside left valve and rocker.
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6023 King Edward II Project
