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December 2011 Progress report

article by: Chris Blake
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The news this month is one of "hot metal" and how to lift the Loco out of its frames.

The month began with some introduction to the volunteers, of a new process to many of us, on how to make up worn and tired bearings. Now that the main elements of the Loco have been put aside for examination, cleaning, repair/replacement and painting the more technical work is being undertaken.

White metalling.

As can be seen in the first two photos, a bearing has been prepared by cleaning off the old "sacrificial" metal. This is not as simple as it looks, as the new metal will need to bond to the shell to ensure long lasting usage. The shell is given a complete wire brush cleaning, degreased and then primed with a chemical etch tined and etched again. At this stage it is important to keep any thermal shock to a minimum, so all parts are heated up prior to the metal pour. You can see in the photo, the former in the middle as well as the two split pieces which form the two halves and allow for the diameter of the relevant shaft. Now, the tricky bit. Heat up your white metal ready to pour, ensure the mould is level and metal tight. The last bit we will find out next! With a steady hand the metal is poured in, right to the top. Cooling now takes places fairly quickly, aided by fine water spray and the parts removed. No leaks! Later on, the white metal will be machined back to the right tolerances ready to be fitted to the loco.

In order to have a more detailed look at the rest of the axle boxes it had become necessary to lift the frames out of the axles. This is no small job, as at present we do not have a frame lift or wheel drop facilities. How we achieved this was a matter of lifting with jacks and blocking as we went up and then placing on frame stands to secure it in place. Now, if you only lift one end at a time and then by 18 inches (150mm) it takes a few hours just to raise each end. Over the course of two weeks we finally had the right height. This then allowed the axle boxes to be rotated and dropped out from under the wheel shafts, once the springs and stretchers had been removed. These are heavy parts and will be inspected for any further damage and wear. (See photo)

After a lot of preparation work, including degreasing, needle hammering and replacement of corroded parts, the cab is now ready to be riveted together. Currently it is held together with nuts and bolts to ensure stability and fit. We feel a more traditional method should be adopted to give an authentic look and feel to the 4F, as we intend to do for the rest of the rebuild.