Working on locomotive cylinders

[John B]

I had a great weekend working on the cylinders, pistons and rings of a 1910 Ww class 4-6-4T side tank engine, NZR number 480, this weekend.

I could not help but think "on how many other heritage railways would an amateur like myself be let loose on such important repairs?"

I filed the insides of three of the piston rings (two to each cylinder) to get a better seat in the piston grooves. I then had to fit them to the piston, quite a tricky job as they are quite substantial and have to be "persuaded" over the piston end and into the piston grooves.

I then trialled them by setting the pistons up inside the cylinder. The piston rings had been milled from cast iron on our own milling machine. This also set me thinking, we are very well set up here at the Glenbrook Vintage Railway as we have our own 1975 Plasser type UT06 ballast tamper liner machine, wheel turning lathes and other vital repair machinery there is very little we cannot fabricate ourselves in our own workshops apart from castings.

One of the old boys was showing me some gunmetal Ross pop valves he'd been turning on one of the lathes, they looked very smart.

Once the piston and rings became a good fit I had the pleasure of fitting the cylinder end, tightening it up carefully and sequentially, each of the twelve studs in turn to prevent undue pressure on any one as this would crack the cast iron cylinder end. I needed help to lift all this gear into place, after which we reconnected all the piston rods, return spring and back cylinder cover before fitting the lap and lead rod. All that now remains to be done on the right hand cylinder is for the cylinder covers to be fitted.

This is all good stuff and increases my knowledge quite substantially, especially useful as I am a cleaner training to become a fireman and eventually a driver. I have a few photos of some of these operations and if anyone is interested I could arrange to post one or two on the forum, though I am a little technologically challenged.