As I write this at the beginning of April the world does seem to be on the way to returning to normal again. The GWSR is to reopen on 13th April and most importantly for TSLL a return to volunteering on the 76077 project is now a reality. While the railway settles back into operation we will again be concentrating our volunteer efforts at the LMS workshops in Loughborough where we are tantalisingly close to wheeling the locomotive. There is still some painting of the wheels and frames to complete before the re-wheeling and an assortment of other work that would be nice to have done before the big day.
Axle boxes fully machined
There has been an enormous amount of work put into the driving axle boxes to ensure they are as good as new. These Standard type axle boxes when fitted to 76xxx loco’s, were good for up to 150,000 miles between general overhauls in BR days, the high mileage attained being a direct result of generous bearing proportions and the use of the manganese steel on the horn wearing faces. The picture above shows two of the completed boxes. There are four machining operations for each box. The first is to machine the manganese liners that are welded to the sides of the axle boxes these are generally ground to ensure they are flat and true to each other. The second is the White Metal thrust face (that faces the back of the wheel) followed by the third operation, the main bore. The axle journal for each wheel is a different size as when the axles are re-machined at works visits, the minimum amount of material is removed to clean up the surface. The bore is then machined to attain a very good finish – as this is the main bearing surface. It is machined approx. 0.020” bigger in diameter than the axle to ensure that there is room for an oil film to be pulled up and over the top of the axle. This means the bearing actually rides on top of an oil film and not directly on top of the axle. No oil film between the axle and bearing means no lubrication, which will result in the bearing overheating. The bore needs to be accurately positioned in the box to ensure the correct axle centres, this is calculated after all the horn measuring and alignment is completed but to give you an idea of the tight tolerances we work too its within + /- 0.002”. The final operation is to put a radius between the bore and the thrust face that matches the radius on the axle. Over the years the axles have been machined down in size which means that the radius on each end of each axle varies slightly, so needs to be measured and matched to each axle box.
Boring the axle boxes on the horizontal boring machine
Starting the process…
Bore completed
The other big news this month is the delivery of our replacement live steam injectors from Barry Gambles at South Coast Steam. One of these injectors was paid for by 76084 Ltd as a replacement for one loaned to them, by the loco’s previous owner Chris Hinton. We are very grateful to Chris who has very generously sponsored the second one. Whilst we were sourcing these parts, we took the opportunity to source the delivery elbows which were again kindly sponsored by Joseph Ball as part of our component sponsorship scheme.
One of the new 10X live steam injectors
One of the pair of new delivery pipe elbows
Thank you to everyone who continues to support the locomotive, it is very much appreciated. Hopefully the next report will include a picture of the chassis re-wheeled.
Andrew Meredith
Engineering Director