19

I thought I'd tackle the handpump next as a bit of a change from tin bashing. Experience with the small pump used during the earlier steam tests convinced me that I needed one with a much greater capacity. I've based the design on the one for Flying Scotsman. That design has a bore of 5/8" but I thought that a bit on the big side so I made mine 1/2" bore by 1-1/16" stroke. It was a bit difficult to fit the pump in as drawn due to the sloping top of the tank. There was not enough height for the top fitting on the valve box. This was not helped by the fact that I also had to mount the pump higher up to get the pivot of the operating lever as close to the filler tube as possible to avoid making the filler tube much bigger in diameter and looking silly. I got around the problem by lowering the valve box so that the hole from the pump barrel is at the bottom of the bore rather than in the middle. I just hope this won't cause problems with air bubbles being trapped at the top of the bore. It shouldn't do as the pump ram goes right to the end of the bore without leaving a gap. We'll see.

The pump body is a fairly simple fabrication from brass bar and brass flat all silver soldered together. The design differs from most hand pumps in that the handle is pivoted on a fixed bracket rather than a loose link fastened to the pump body. Instead there is a pivotted link connecting the bottom of the lever to the pump ram.

Fabricated pump body

02/06/2007

The pump piston is turned from stainless bar and looks very much like a car engine piston with a gudgeon pin and a single 'O' ring. The operating lever is fabricated from brass bar with a boss for the pivot pin silver soldered in and the connecting link turned from brass bar.

Piston and lever assembly

The valves are 3/16" dia. stainless balls seated in the usual manner with a light hammer blow. As height is limited in the rear bunker the feed pipe is silver soldered into the top fitting of the pump rather than using a screwed connection. This does mean that the pipe has to be bent to clear the pivot supports when the fitting is screwed into place but it has to be bent anyway to connect to the fitting on the front of the bunker. The pump is bolted in place using four brass studs soldered into the bottom of the tank. The extension lever for operating the pump is simply a 6" length of 3/8" dia. stainless tube.

Pump assembly fitted into tank

Tank top in place with pump operating lever fitted

On Sunday 27th May I took the loco to the Rally at Stafford and Steve gave the boiler it's 'official' hydraulic test which it passed with no problems. The weather was awful and Helen got a good soaking but after the test I sneaked her into the Club hut to dry out a bit! Just before we left I 'played' trains and pushed Helen around the track. There was a reason for this as I wanted to see how the chassis negotiated curves as I was a little concerned that the bogies would not have enough clearance. However, there did not seem to be any problem on the curves at Stafford which are fairly tight due to the limited space for the track.

I've booked Helen in for the final steam test at Rugby on June 10th so I've got to get cracking and get her in a steamable condition. There's only the pipework for the pumps to sort out really and a few little jobs like making the second safety valve. Hopefully I will be able to give her a run on the track!

I am still a little concerned about whether the boiler will be able to supply enough steam for the three cylinders. This feeling was not helped when I was told at Stafford that another chap with a Helen Long could not keep his in steam! Simon Clough is a regular visitor to the rallies with John Cook's Uranus which is very similar to Helen with three big cylinders and goes very well. However Uranus has a huge boiler with an enormous firebox and a combustion chamber. Helen's boiler is tiny compared to that! Oh well, we'll just have to wait and see.

15/06/07

Preparation work for Rugby consisted mainly of plumbing in the handpump and the axle pumps, putting everything together so that the loco could be given a steam test and a test run, and actually firing the boiler on coal which I had not done yet.

The hand pump feeds into the right-hand bush at the front of the boiler and the axle pumps into the left-hand bush via two clack valves. These are smaller editions of the one made for the backhead and use 5/32" stainless balls instead of 3/16" to keep the size of the clack more to 'scale'. The connecting pipes from the hand pump and the axle pumps are 1/8" diameter thin wall tubing which allows adequate flow without looking too big. The outlets from the two axle pumps are connected together with a manifold made from brass bar and as well as the two pipes from the pumps carries two connections at the ends. One of these is for the pipe to the boiler clack and the other to the by-pass valve fitted to the end of the right-hand tank inside the cab. This valve is basically identical to the blower valve and controls the amount of water returned to the tanks and hence the amount fed into the boiler. A smaller manifold connects the inlets of the pumps and is fitted with two pipes which connect to pipes on the inside of the side tanks via lengths of silicon tubing. I am not altogether happy with this arrangement as the connections to the side tanks are really too high up and run dry when the water level falls. The ideal place to take the feed from is the rear bunker as this is the lowest point but this means an awkward pipe run to get past the ashpan etc. When I get around to making the driving trolley this will carry an additional water tank, the feed from which will be arranged to automatically keep the loco tanks full (hopefully!)

Pipework for the axle pumps

At this point I also made a top for the lubricator (about time!) which was a piece of 1/4" brass bar with 1/8" square locating strips soldered underneath to fit inside the lubricator tank. The underneath of the bar required a recess milling into it to clear the rotating cams of the driving spindle as at the highest point they protruded from the top of the tank.

I had been wondering what to use for insulation on the boiler and eventually decided to use cork sheet which was ordered from one of the many modelling suppliers. I actually ordered rolls of 1/32" and 1/16" thick as I thought I would only be able to get a 1/32" layer over the firebox but I was sent 1/16" and 1/8" instead! As it happens the cork is actually thinner than it says so I think I can use one layer of the 1/16" over the firebox and two layers over the barrel. For the time being I just fitted a single layer over the barrel and secured it with thin copper wire.

The boiler was then fitted into the frames. The front is of course secured by the smokebox saddle (the smokebox is secured to the boiler by brass screws into the end of the boiler barrel) but the firebox end needs to be held down but still be able to move slightly to allow for expansion. Prior to the hydraulic test I had fitted a length of brass angle across the bottom of the backhead which was held in place with brass screws tapped into the foundation ring. The angle is the same length as the gap between the frames and when the boiler is in place two short lengths of angle are bolted to the top of the frames and just touch the boiler angle. Thus the boiler cannot be lifted but is free to move slightly when it gets hot.

Rear boiler fixings

Inside the smokebox the holes in the bottom where the exhaust and steam pipes enter are sealed with silicon O rings clamped in place with a washer and a nut threaded onto the pipes. Previously the steam pipe connection from the superheater hot header to the steam manifold stub had been sealed with another O ring but after the initial tests using the gas torch for firing the O ring here seemed to have disintegrated, possibly due to the high level of superheat. This time I fitted a sealing ring turned from PTFE and this seems to stand up to the high temperature better. The worst part of the smokebox plumbing is the connection for the blower pipe on the boiler tube plate which is right at the back and very difficult to get to. Eventually I made up a special right angled spanner to tighten up the union nut which made the job much easier.

The next job was to fit the side tanks and these are connected to the rear bunker tank with short lengths of plastic tubing. Then we were ready for steam testing again.

Ready for testing!

Helen was set up on the rolling road again for these tests. The boiler was filled half way up the glass with filtered rain water using the handpump. This was accomplished fairly quickly due to the high capacity of the pump (much better than the small pump used before!).The fire was started using the usual charcoal (ordinary barbeque type broken up) soaked in BBQ lighter fuel. I'm not sure what this lighter fuel is but it seems to be more volatile than paraffin and ignites easier. With the electric blower on the fire was soon roaring away merrilly and the pressure gauge started to creep up. The steam blower was opened at 20psi and provides an excellent draught at this low pressure enabling the electric blower to be dispensed with after only a short time. Steam coal was then gradually added until a good fire had been built up. The pressure rose quite rapidly to blowing off point when the blower was turned right down.

One major problem became apparent immediately I used the handpump to top the boiler up - the pump locked up solid and refused to pump any water at all. With the water level rapidly disappearing in the gauge glass I had no choice but to let the fire die out which was a shame as it was burning nicely! Investigation of the problem showed that the fault lay in the boiler clack rather than the pump. What had happened was that the O ring seat for the ball had lifted up with the ball and sealed the clack completely stopping any water flow through the clack. As a temporary solution I removed the O rings from both the clacks and just let the balls seat on the bronze body. This meant that the ball lift was now too great by the thickness of the O ring but subsequent tests showed that the clacks still worked perfectly.

The fire was then lit again and this caused a few problems because I tried to light the new fire on top of the old one and it was difficult to get it burning all the way through. I managed it eventually after using lots of charcoal but it would have been much easier if I had cleaned out the old stuff and started again! The next hour or so was spent playing with the fire and trying to keep it going whilst running the engine. A couple of times I lost pressure due to the fire partially going out, either at the front or rear of the grate. It's such a long firebox that you have to keep your eye on the fire all the time and make sure it's burning evenly all the way along.

Blowing off at 90psi

Running on the spot!

View of the fire

For the initial tests I still had just one safety valve fitted which proved to have a very 'soft' action and blew off quite early and shut off very late allowing the pressure to drop quite a lot before sealing again. I then broke off testing to make the second valve. I made this one with a (hopefully) pop action which would keep the boiler pressure more constant. Basically the difference between a pop and non pop valve is that in the pop valve the ball sits inside a recess in the bottom of the valve which is only slightly bigger in diameter than the ball itself. This gives the valve more of a 'snap' action and the ball lifts suddenly rather than gradually.

The second valve was fitted and the boiler fired up again. Well, this new valve certainly popped! It didn't half go off with a bang and promptly dropped the pressure down to about 60psi and nearly emptied the boiler! A little bit too violent I think! The valve was removed and the depth of the recess reduced down to about 1/16". This improved the action consideraby and it blew off with a gentle pop this time and shut off quite quickly. Much better! As I was happy with this I altered the original valve by machining a similar shallow recess for the ball. Although the valves seem to be more or less the same further testing showed that the original valve still doesn't have much of a pop action at all and still blows off gradually. Still, they both work ok so I'll leave them as they are. The only other thing I did was alter the lengths of the springs so that when set at 90psi the threaded adjusters protruded by about 1/8" above the tops of the bodies. This allowed the fitting of thin hexagon locknuts to prevent the adjustment of the valves shifting in service.

Further testing followed when a few problems showed up:

The pivot screw for the hand pump worked loose and made operation of the pump awkward. This was entirely my fault as it should have had a locknut on the end which I hadn't fitted. Putting this right involved the removal of the top of the rear bunker which had been sealed in place with red Hermetite. Very messy!

Also it soon became apparent that the cylinders were not getting enough oil as the valves kept tightening up during running and at one point the centre valve eventually seized and sheared off the three 8BA bolts holding the pivot bracket for the 2 to 1 lever! Investigation of this problem showed that the spring drive to the lubricator shaft was allowing too much 'slop' before driving, in fact it was hardly driving at all. I spent quite a bit of time making new springs to try and solve the problem. I did manage to improve matters somewhat but I wasn't happy with it. Rugby was rapidly approaching and I was running out of time. In the end I ordered a couple of 1/8" bore needle roller clutches from Arc Euro Trade which fortunately came next day. Fitting one of these only required the making of a new drive arm for the lubricator and this solved the problem completely. The spring which prevents the lubricator shaft moving on the return stroke of the operating arm was left in situ as this works perfectly. It was only the spring that actually turned the shaft that was causing the problem. Incidentally, it is recommended that the shaft that these roller clutches work on should be hardened to reduce wear but as the shaft on Helen's lubricator is silver steel I think it will last this season as it is. Further tests showed that the pump was now working fine and I actually reduced the travel of the arm to reduce the oil feed. Just in case I did not manage to solve the lubricator problem I had ordered a lubricator kit from Steam Fittings which also arrived the next day. If all else failed I was going to connect that up temporarily so that I could run Helen at Rugby!

The water gauge was proving to be very unreliable due to the small diameter of the glass. Once when filling the boiler from cold I managed to completely fill the boiler without anything showing in the glass! On the Friday before Rugby I made a new fitting using 3/16" diameter glass and this has proved a lot better. I fitted a length of 'Red Stripe' gauge glass which has a red stripe all the way down with a white stripe either side of this. The glass is fitted with the red stripe at the back and the water in the glass shows as a solid red line which makes it much easier to see.

At the same time as ordering a lubricator from Steam Fittings I ordered a 3/4" diameter 150psi pressure gauge and fitted that rather than the 1/2" 120psi one which was too small to see easily. Also the gauge could be left on for future 1.5x hydraulic tests.

The final job was to cut out and temporarily fit the tops for the side tanks. During the steam tests a lot of ash and grit from the chimney got into the tanks due to them being open and I did not want that to get into the pumps and the boiler anymore. I drilled a 3/8" dia. hole in the right-hand top which allowed the water returned by the by-pass valve to be seen showing that the axle pumps were working.

The Saturday night before Rugby I gave Helen another steam test to check the safety valves, the new water gauge, and the new pressure gauge. This time I used the gas torch again rather than coal as I did not want to have to clean her up again! It took ages to build up pressure using the torch which just goes to show how much more efficient the coal firing is. Also this time I fitted the big pressure gauge to one of the steam valves so that both safety valves could be tested at once. The new 3/4" gauge matched up with the big gauge and the safety valves both lifted at 90psi so we were all ready!

16/06/2007

Just come back from Rugby after a really good day. Helen passed the steam test with flying colours and I got to give her a run around the track! I was full of trepidation at the thought of making my debut run in front of all those people especially since I didn't know if Helen would run at all and I had never driven a loco before! Still, there's got to be a first time for everything. Des Adeley lent me a driving truck (next project!) so there was no turning back! The track at Rugby has a very steep climb up from the traverser where you join the track so that made matters all the worse and I didn't expect to even get to the top. However, taking the bull by the horns, I opened the regulator with the reverser at about 3/4 of full gear and she pulled off steadily with no wheel slip at all and accelerated up the bank as though it wasn't there! By the time I got to the top I was travelling at a fair turn of speed which I found a bit disconcerting! With being so close to the ground you seem to be travelling a lot faster than you really are. Anyway, I eased off on the regulator and wound the reverser back to just off mid travel and that slowed things down a bit and I felt a bit happier! However, I could see that the pressure was going down in the boiler and after about 7/8 of a lap it went altogether and the fire looked pretty dead so I pushed her back to the traverser and took her off to rebuild the fire and try again. Still, I was dead chuffed that she had got that far as I was fearing the worst!

Rather than try to resurrect the old fire I dropped the grate and started again. Peter de Salis-Johnston gave me some different coal to try so I mixed that with some of the coal I had. Peter's coal is a long flame steam coal that he is trying out and burns very hot but makes quite a bit of smoke. It all adds to the atmosphere though! Anyway, we were soon back up to pressure and back on the track for another go. Some-one sugested leaving the blower on a bit all the time to help the fire so I gave this a try. This time we sailed up the bank with the safety valves blowing off all the way and they kept like that all the way around. Big grins all round! I did another circuit and then stopped to put on more coal as I didn't fancy trying to fire on the run yet. Off we went again for another two laps before stopping again for coal. More grins and I was really enjoying myself now! This time I went for three laps but I think I let the fire get too low before putting on more coal and I lost pressure on the next lap, travelling the last half lap on about 20psi. I couldn't bring the pressure back up with the blower so decided to call it a day and quit while I was ahead! It was getting late anyway.

All-in-all a very successfull day. I've now proved that the boiler can produce enough steam for the cylinders which was a major worry (I just have to learn how to fire it properly!), the valve gear etc must be ok as she runs well with the gear well notched up, and, finally, nothing fell off! I now feel confident in the design and can carry on with the cosmetic work and get her finished. Can't wait for the next rally!! Many thanks to Steve for doing the boiler test, Des for lending me the driving trolley, and Peter for the coal! Unfortunately in all the excitement I forgot to ask brother Mick to take some photos of her running. However, there were quite a few taking photos and videoing the run so I may be able to get hold of some to put on here. (If anyone reading this has any photos that they could send me it would be much appreciated)

Another highlight of the day was seeing an original Helen Long which had been brought along by Robin West and which he hopes to have running again soon. I took the opportunity of having a look at the middle cylinder and noted that it is set quite a bit higher that the outside ones, far higher than is suggested by the original drawings. I had already deduced that it would be necessary to set the cylinder higher to fit it in the frames so here was the proof.

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