Myrtle Anne

This is another loco belonging to friend Tony who owns the Kingette. She is another 'oldie' probably built in the 1930's. She still has the original rivetted and soft soldered boiler which is still in good condition and passes the required tests with no problem. It makes me chuckle when I read all the hoo haa about 'modern' boilers and how they must be all silver soldered at all cost with no soft solder to be seen!

Myrtle in original condition as purchased

She's very much worse for wear now but was well built originally. She's very highly detailed and whoever built her went to a lot of trouble to add all the 'blobs and gadgets' as old Curly would have said. Tony never had much luck trying to run her so I volunteered to take her home and give her the once over.

She was given a good clean with parafin to get rid of years of accumulated muck and grim and then inspected. The valve gear and motion was very worn with plenty of 'slop' in the joints and I don't think the packing on the pistons was doing a great deal. Taking the bull by the horns I removed the cab, running boards, and boiler so that I could get at the cylinders. They were then removed and dismantled to see what condition they were in. The port faces were badly scored as expected after all this time so these were restored by rubbing on carborundum paper on the surface plate and the valves given the same treatment. The cylinder bores were ok but the old packing in the pistons was replaced by 2 PTFE rings (as per Helen). O ring seals were fitted in the glands to replace the packing in those. Having done this, the cylinders were replaced and the valve timing checked. This was all over the place, probably due to all the wear in the joints so I set it up as best I could with the reverser at about 60% cut-off which I guessed would be the normal running position. The boiler etc. was refitted and she was taken for a test run down the track.

The performance was much improved but she wouldn't maintain pressure and the fire never seemed to burn properly which would not help the steaming. So, back to the shop! I looked at the chimney and blast pipe design and this did not match the LBSC drawings at all. I quickly did a redesign using the articles in ME by Harold Barton and this showed the front end arrangements were miles out. The chimney was too big in diameter and the blast nozzle too low down. I made a new liner for the chimney and a new blast pipe and gave the loco a run on the rolling road. This did improve things a lot but the fire still seemed a bit dull at the front of the grate. The ashpan (if you could call it that!) was completely open at the bottom but looked as though it had been blanked off at some time so I fitted a metal plate that left the back of the ashpan open and also left a small gap at the front. This made a big difference and the fire burned well all the way along. Another run on the rolling road was a success with the safety valves blowing off most of the time. With the bottomless ashpan, the air was just taking the easiest route through the fire rather than evenly all the way along the grate.

Running on the rolling road

She ran like this most of last year and put up some good performances. One time we had her in steam for 2½" hours when she was driven by several different drivers. We did notice that she did not like running with the axle pump on full as pressure would eventually drop off as the water level rose so it was a case of do a lap or two and then stop to put some water in and wait for the pressure to come back up. Being a 4-4-0 she's very light footed and the regulator has to be handled with care otherwise the wheels just slip like crazy. She did act up once but I eventually noticed that one of the return cranks had slipped (they are not pinned) and one valve was hardly moving. Resetting that put things right again.

Towards the end of last year though, her performance seemed to drop off and the last couple of times I drove her I could not get around the track without stopping for a blow up now and again. Also, the water gauge was acting up and showed no water when the boiler was actually full. I offered to have another look so brought her home again.

I suspected one or two things: the boiler may be clogged up with gunge in the bottom of the firebox water space as there is no blow down valve fitted (they didn't fit them in those days!), or the valve timing had gone astray again.

Off came the boiler again and the first thing to check was the water gauge. It turned out the bottom fitting was partially blocked which explains the erratic readings. I gave the boiler a good rinse out and quite a bit of muck came out. I think this was mostly coal dust though drawn in with the water from the tender. I next wanted to see if the water legs of the firebox were blocked up with scale etc. but couldn't see inside to check. What I did was to prop the boiler up so that the line between the bottom fitting on the water gauge and the bottom of the barrel was horizontal. I then poured water into the boiler until it ran out of the fitting. The amount of water in the boiler would then equal the space around the bottom of the firebox walls. If this was full of rubbish then the amount of water would be very small. What water was in there was poured out into a jug and measured. It didn't seem very much (about 50cc's) but a quick calculation of what the space should hold showed this to be about right so the spaces must be clear. No problem there then.

Next I had a look at the valve gear and decided to try and get rid of some of the play. The die blocks in the expansion links were very worn so I made new ones from the bearing grade PEEK. I just filed these up by hand rather than set the rotary table up and mill them. Also, the trunnion pins on one expansion link were very loose in the bearings so I made 2 new pins for those and fitted them. I replaced a few pins that were excessively worn and that improved things no end. When I came to set the valves though I had real problems and it turns out that one valve was too long and opening very late (the lap was excessive) and the other was too short and opening much too early, so early I think it was trying to make the piston go backwards! Out came the valves. One was easily shortened by milling an equal amount of each end and the other was 'stretched' by soldering a little strip of brass on each end and then milling to size. Having valves the right length made a big difference but the valve travel was still all to cock. When the valves were set properly they moved much more in one direction than the other. They opened at the right time but one port was open for much longer than the other.

Out of interest I put the valve gear dimensions into a valve gear simulator (the one by Prof. Bill Hall) and that proved that what was happening in practice happened in the simulator. The problem proved to be the backset of the expansion link. This was too small and was causing grossly unequal valve travel around the mid point of the valve. As drawn, the backset is 0.0625" but it needs to be something like 0.20". There's one or two other dimensions which are wrong as well but the backset is the major culprit. For the time being I am just going to leave things as they are and make do. In the future, Myrtle may have a complete rebuild and that will be the time to sort the valve gear out properly.

Once the valve gear was reassembled and timed I ran the chassis on air and it ticked over on just 5psi so things looked promising!

Another run on the rolling road proved to be disappointing as I thought I might have cracked it now the valves had been put right. The loco ran much better and now notched up well (which she would not do before) but would not maintain pressure. I tried various mixtures of coal but with no joy.

I decided to try a run on air again to check for leaks and did this by connecting the air supply to the snifting valve so that I didn't have to disconnect anything on the boiler. She would not run at all this time and I could hear air escaping from somewhere inside the smokebox. Using a 'stethoscope' (a bit of plastic tubing stuck in one ear!) I traced the leak to the superheater header where it bolts to the flange on the front tubeplate. The snifting valve screws into the top of this as well and I thought that it might be that leaking so I took it out and resealed it with PTFE tape on the threads but something still leaked. It looked as though the superheater element might have corroded through where it is soldered into the header and had a pin hole in the pipe. Oh bother (or something similar!)

The only thing to do was to remove the superheater which I thought would be a nightmare of a job. The header is held on by 4 nuts which proved to be quite loose so I tried tightening these up first to see if that was the problem but no, the leak was still there. The superheater had to come off after all. As it happens, it proved quite easy to remove and just came out through the smokebox door! I did have visions of having to remove the smokebox. The element proved to be sound and it turns out it was the gasket between the header and the tubeplate flange that had 'blown'. I drilled a recess in the header to take an O ring rather than fit another gasket and refitted the superheater. This time there were no leaks!

Back on the rolling road again and what a difference! She blew off continuously even with the axle pump on all the time and used much less water than before. It's quite possible the superheater gasket has been leaking for some time and the leak has gradually got worse over the last few runs. We haven't given her a run on the track yet (should be soon) but hopefully she will be a different loco!

07/05/12

As mentioned in the Kingette write up, friend Tony passed away last November. His widow has decided not to keep Myrtle so she will be put up for sale. Although she has run quite well over the last few years, she's started to get a bit tired again and needs some more work doing. I've suggested that I'll get her sorted again and then advertise her for sale.

The first thing I've done is to have another look at the draughting as she was struggling to maintain pressure again. I decided to try a slightly smaller blast nozzle to give a stronger blast and made a new liner for the chimney to suit. I've found that due to the big cylinders she needs to be run well notched up to avoid slipping the wheels and this reduces the available blast quite considerably. A run on the rolling road showed that she had no problem maintaining pressure and would run almost in mid gear, so the valve gear perhaps isn't as bad as first thought.

At the end of April I took her to the club for a 2.5" running day but she again struggled to get round the track (ours is quite a test for a small 2.5" loco!). I noticed that there seemed to be a lot of drag from my 4 wheeled driving truck (I had noticed that Tony's was the same when I last used his), especially on the curves. This caused her to grind to a halt with wheels spinning. Out of interest, I decided to try one of the club's driving trucks which are to the David Hudson design with self steering wheel sets. What a difference! Old Myrtle flew around the track as though pulling a feather. I couldn't believe the transformation. I managed quite a few laps before loosing the fire and then I couldn't get it burning properly again. It's possible a couple of the tubes had got blocked but I'm still not happy about the ash pan arrangement. I've a feeling it's too open at the back and perhaps lets too much cold air through the back of the fire. Something else to look at.

With regard to the driving trucks - I think the long wheelbase 4 wheeled trucks such as mine and Tony's have too much drag for a small 4-4-0 loco like Myrtle and that's why she has always struggled a bit. When I used the Hudson design truck she never slipped the wheels once, even when tackling the tight bottom curve of our track which is also quite a steep climb. Bigger locos such as my Helen can cope with a bit of drag without problems. I think I am definitely going to make one of the Hudson type for myself when time permits.

20/06/12

After the previous run at Whitwick I had cleaned out the loco and a couple of the tubes were indeed blocked which explains why I had problems with the fire later in the day.

My brother and I took Myrtle to the 2.5" rally at Rugby on the 10th and gave her another run. After a couple of hesitant laps brother Mick had a good run with her and managed 4 laps without stopping (about 1 mile) so it looks as though she is back to her old self again. Mind you, he's a better driver than me!

10/07/2019

I've moved this section from Miscellaneous Jobs to '2½" gauge Locos' as it's returned to me following rather unfortunate circumstances.

The loco was eventually sold to Cliff Barratt, another memebr of the 2½" gauge Association who lived in Stockport. He dismantled it in order to do some restoration work and repanting. Sadly, Cliff passed away before he had chance to rebuild the loco and it sort of disappeared.

I was on Ebay the other day (as always!) and saw a chassis and boiler for sale by a dealer in Stockport. I instantly recognised it as Myrtle Anne even though a lot of the original loco was now missing. Obviously, the tender and a lot of other bits have got lost since Cliff's death.

Anyway, to cut a long story short, I bought the remains with a view to restoring the loco back to running order. It's going to have to have a lot of new parts made including a complete tender, unless by some miracle the original turns up. The cab, running boards, cladding, smokebox door, lubricator, front bogie, axle pump and most of the boiler fittings are missing so will need replacing.

 

 

I wish that I had taken more photos of the original loco now but I will have to make do with the few that I have.

I've got at least one front bogie that I can use to replace the missing one but everything else will have to be made from scratch.

It's a project for the future as I've other things to do first but it would be nice to have it running again. We had some good fun with it when it was running.

 

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