Saturday, 24 May 2014

Sanding Gear (1)

After a few months of apparent inactivity with Sentinel 7109, things have actually been happening (although much of my time of late has been spent defining safety critical operational roles and training material for Midsomer Norton); the first of these is the fitting of a replacement sandbox pipe at the off-side front.

For ages, there have been three original pipes painted and ready to fit to feed sand from the four sandboxes to the rails; however, the fourth one had disappeared some time ago or so I thought. I'd searched and searched, convinced that the fourth one existed, but finally resigned myself to having to make a new one, flange and all.

Eventually, on close examination of the sand box itself, I found that there was a flange still in place underneath with clear evidence of a pipe having been broken off from it.

So I'd been wrong; the fourth one hadn't existed after all.
New Sand pipe (1)
The new pipe is made from mild steel with a longitudinal weld, i.e. not malleable iron or cold-drawn seamless steel. A 3/4" BSPT thread needed to be cut to fit the flange on one end before bending to shape. (It's difficult to clamp a bent pipe for thread cutting!).
New Sand pipe (2)
After shaping into a mirror image of the near side front pipe using a 12 ton hydraulic pipe bending machine, the lower end was cut diagonally to feed the sand into just the right place.

Finally it was screwed into the threaded flange still attached to 7109. (28 tons of solid metal certainly held the flange tightly in place!).

There's much more to come on sanding gear, particularly working out how the levers need to operate the four boxes.
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