Friday, 25 January 2013

Achilles Report No23: Taking Her To Bits...

Hi guys. Well, as reported in the last Achilles post, the time has come to take her to bits for a bit of a bottom-end overhaul, amongst other jobs. This afternoon I grabbed my toolbox and a cuppa' before setting to work on the loco, taking off the right-hand side valve gear. A constant problem with the loco has been the worn crossheads, which bang up and down against the slide-bars when she's running along. Both of the crossheads are due for replacement during this period, as well as all of the bronze coupling rod, big end and little end bushes. Unfortunately, to get to the bushes, you need to remove the valve gear and then remove the connecting and coupling rods. On "Achilles", the first thing I removed was the return crank arrangement, and then the rest of the valve gear. Unfortunately, due to a sheered crosshead pin, the only way to remove the crosshead, and of course the gudgeon pin, was to undo the cylinder end and remove the entire piston assembly too. It took about 2 hours to get the loco to the dismantled state which saw the valve gear completely off. Below, I've taken off the RHS running plate to reveal the top of the cylinder and of course allow access to the di-block hanger and valve spindle...
The main thing with a job like this is to make sure that you have all of your tools to hand. Luckily I've ammassed quite a selection of allen keys, spanners, socket sets and screwdrivers over the years which does help, along with the traditional engineman's spanner (a big hammer). A good mug full of tea is also imperative when doing work like this to your engine. Below, the top slide-bar has been removed and the gudgeon pin nut is off...
In the image below I have also removed the top of the steam chest to check the condition of the valve. The rest of the gear which operates the valve has been removed...
In an image that startled even myself when I took it, the cylinder end and the piston have been removed, allowing the crosshead, connecting rod and lower slide-bar to go too...
The removal of the connecting rod then allows access to the front crank pin, which holds its bush, and indeed the coupling rod, in place by means of a caphead screw. The coupling rods for the RHS were then removed and laid on the bench. The bearings do not look terrible but none the less there is alot of play so they shall be replaced, taking the size off the current crank pins as our measure, rather than the drawing size (as the crank pins are not new and, though made of much harder material than the bushes, may have also worn). Below, the loco has had the cab removed as well as the bunker...
It certainly is interesting learning about the make-up of the locomotive when you've taken it apart. The bushes for example, for those who are not familiar, are simply bronze inserts which seperate the rod from the crank pins they revolve around. The bronze bush is designed to wear much quicker than the crank pins themselves, as the bushes can be replaced rather easily, once off the engine that is.
The removal of the cab has allowed me to get to the fittings much easier. A leak on the whistle turret has resulted in me taking it off completely and finding a decayed fibre washer. The washer has been removed, as has the gauge glass as that was leaking through its bottom fitting. The latter will require a new brass or fibre washer to be fitted in order to ease and of course seal the leak. The fittings will be replaced when I receive the fibre washers. She may also need a new gauge glass as the old one is looking a little tired.
One thing that I will be attempting to sort out is a slight problem with the loco's valve timing. Something isn't right...she goes pretty well but not as well as she should. Having taken up the valve gear slack I will be attempting to set the timing again. Below we can see the RHS valve inside the chest...
Thank you for reading folks. The next job on "Achilles" is to remove the LHS valve gear and then remove the bushes from the rods so that new ones may be made. Progress will continue to be reported on this blog where possible. Cheers guys - Sam.

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