The crankaxle has had a lot of attention. Colin Boyd measured up the crankpins for ovality and parallelism. We knew from the previous overhaul that the RH pin is slightly tapered (for reasons unknown) and Colin confirmed that this is still the case. Now that we have the sizes Nathan will be able to machine the big end bearings to size and then we can get them scraped in to the required fit.
For the first time in more than half a century the eccentric sheaves have been removed from the crank axle. This is not a job for the fainthearted but Alan French made up an excellent special tool that allows the square headed clamping screws to be accessed deep inside the eccentric castings. The castings are a beautiful piece of 19th Century workmanship but they are heavy....very heavy..! Once the sheaves were removed it was a matter of cleaning them up and then reassembling them so they can be checked for wear. Three out of the four were found to be surprisingly unworn but the RH forward eccentric is the exception and shows about 0.037" of ovality. So that we give the newly white-metalled eccentric straps the best start in life all of the eccentric sheaves will be mounted on a mandrel in the big lathe and skimmed back to full circularity. There is therefore a lot of lathe work coming up in the next couple of weeks...
|Removing the gauge glasses in preparation for the boiler hydraulic test. The regulator handle will need a lot of polishing before 828 goes back into service.....|
|Removing the gauge glass fittings requires some special tools......!|
|Bothe gauge glasses removed and blank flanges fitted for the hydraulic test|
|Crank axle with the RH Eccentric Sheaves removed. The LH Eccentrics are still in place. The leftmost of the two is the eccentric that gives forward motion; the other one gives backward motion.|
|The crankaxle with both sets of eccentric sheaves removed. As a "fully built" axle it consists of nine individual parts pressed and dowelled together. Manufacturing a replacement would be horrifyingly expensive today....!|
|One half of the LH eccentric sheaves being cleaned in the Shed's parts cleaner - a very useful piece of equipment indeed.|
|Both sets of eccentric sheaves on the bench at the north end of the shed. It takes three people to lift them when they are assembled. Nathan Lightowler is measuring the diameter at 90 degree intervals so that we can check for wear.|