2½" Gauge Kingette

This loco was purchased by a fellow member of the 2½" Gauge Association who is also a member of our club at Whitwick. When he bought the loco, it was suggested that it may be the loco being driven by Cyril Grose on LBSC's Polar Route in a phtograph in Brian Hollingsworth's book 'LBSC, his Life and Locomotives''. We have tried to obtain evidence to support this but with little success. I have compared the actual loco with the photo and there are some very similar features between the two locos, so much so that I think it could well be the same one. It would be nice to trace the original builder but this may be very difficult, if not impossible, after all this time.

Click on thumbnails for a larger photo




The loco was displayed on the Association stand at the recent Midlands Model Engineering Exhibition (October 2008) and one of the Stewards on the stand suggested somewhat strongly that it was about time the owner did something about the 'tatty' condition of the engine!

We had talked previously about a possible refurbishment of the engine with a view to getting it running properly again and the owner got in touch to see if I would be prepared to carry out the job (Mad fool!). I said I would be happy to do so and so the engine is now in the workshop. I thought it might be of interest to report the progress of the rebuild on these pages so here goes! I will probably do this as time permits as I want to carry on with the Simplex as much as possible so this job may take some time over the coming winter.


I've made a start by dismantling the loco down to it's basic parts to see what work will actually need to be done.

A couple of hours saw the cab and boiler removed from the frames. The worst bit was fathoming out how to disconnect the outside steam pipes! Eventually I sussed that they consisted of screwed elbows connected by bits of threaded copper pipe, very similar to the steam and exhaust pipes described by Martin Evans for Rob Roy etc.. By screwing the pipes into one of the elbows, this releases them from the other elbow and allows that to be unscrewed.

It was immediately obvious that it is not the original boiler, although I don't know how 'old' the new one is. It is stamped CRB ENG and I am told that the builder is Colin Bushel from CRB Engineering. Apparently he built the boiler for Chris Vine's Gold Medal winning 7¼" B1, 'Bongo' so that's a pretty good recommendation to me!

Whoever fitted the new boiler made a pretty poor job of refitting the firebox cleading and the cab so this will have to be sorted out later.

The 'new' boiler is fully silver soldered and looks very nicely made so there should be no problems there. The only thing that bothers me is that when I had to drain the boiler (it still had water in it from the last steaming) I had great difficulty getting water to come out of the blowdown valve. I thought it may be blocked up (probably never been used!) so I poked it out with a bit of wire and cleared out the bore of the valve. This made a slight improvement but not a lot. I am wondering if there is some sediment sitting on top of the foundation ring blocking the way to the valve. I'll investigate this further when I get to looking at the boiler and the fittings.

The actual chassis was a bit of a nightmare to dismantle, particularly the inside motion which is pretty cramped! The exhaust pipes to the outside cylinders again consist of elbows and screwed pipes and were very fiddly to get apart.The first job though was to give it a good clean down with paraffin to remove years of congealed oil and ash etc. Before getting the spanners out, I took a load of photos of the chassis which will help when it comes time to reassemble it again.

I eventually managed to get it all apart but getting it back together will be quite interesting! It's all got to go back in a certain order and the construction articles by LBSC (in ME 1932/33) are not a lot of help, in fact there is not much building information at all.

There are quite a few differences in the valve gear from the original plans and no doubt I will find others as I go along.

Obvious problems that have come to light so far is that the rear axle and axle boxes are very badly worn and will need replacing which will mean removing the wheels. The other axles are better but still a bit loose fitting. The valve gear pins are all worn, as expected. The coupling rod bushes are very sloppy and the crankpins are badly worn. The cylinders and valves, however, look in very good condition and the ports are very well cut, unlike some I have seen!

On the whole, the original workmanship seems good and whoever built the loco knew what they were doing. Unfortunately, the loco has suffered a bit at the hands of others.


I've now stripped the paint off the frames and stretchers etc. although there wasn't that much left to get off! Rather surprisingly, the frames are very rough and don't seem to be as well made as the rest of the parts. They were anything but straight and I spent quite a bit of time with a hammer and the vice getting rid of all the kinks, bends, and curves! They are still not perfect but I doubt if I can get them much better without a great deal more work. The frames have some rather large cut outs in them as per full size and this makes then less than rigid and easily distorted. The outside edges of the horns and some of their securing rivets were still proud of the outside of the frames but a few minutes work with a file soon sorted that out.

I then bolted the frames together to check the horn slots were in line and it was obvious that although they had been cut and filed to shape as a pair, most of the holes had been drilled in each side of the frames separately and very few of them actually matched! The holes for the weighshaft bushes were way out of line and the weighshaft must have been at an angle across the frames. I managed to find enough to put half a dozen bolts through and these must have been the ones used to hold the frames together in the first place when cutting them out. Heaven knows why none of the others had been drilled while the frames were together. Even the cylinder mounting holes are different on each side! I am beginning to think that this rebuild may not be as easy as I first thought!

Fortunately, all the horn slots were spot on in line so they must have been all machined while the frames were together. The leading and middle horns are only slightly worn, being a few thou wider at the bottom than the top. This may be due to wear or it could be that they were not cut perfectly parallel to begin with. This can happen if they are machined with a small diameter endmill as the endmill tends to flex and spring away from the bottom of the horn slot when you are cutting the full depth. Anyway, I think I'll leave those horns alone for the time being as I don't really want to touch them if I can help it.

The rear horns, however, are badly worn so I've trued them up in the milling machine. I've got to make new axle boxes anyway so the fact that the slots are now slightly wider than before won't really matter.

Truing up the rear horn slots

Whilst the frames were still bolted together, I filed out and redrilled the holes for the weighshaft bushes so that they were in line. This will mean making new bushes to suit the now oversize holes. I'm hoping that all this remedial work will not lead to more problems further down the line!

I thought it best to now do a trial reassembly of the frames to see whether they come out true and square before I go any further. One set of fixing holes in the right hand frame for the front buffer beam angle were miles out and needed filing to get them to line up correctly. The rest seem ok so far and with the front and rear buffer beams bolted on and the round frame stretcher fitted, the frames sit on a surface plate without rocking. So far, so good! I'll fit the rest of the stretchers and see if this remains the case.

Frames partially reassembled to check alignment


I've temporarily fitted the pump stretcher, inside motion bracket, expansion link bracket, and the front bogie stretcher to see if bolting these up affects the frame alignment. Everything still seems square so should be ok to reassemble them permanently. Some of the holes are elongated and a bit oversize so I may replace the existing 7BA bolts with slightly larger 6BA and ream the holes to suit. I also tried the inside cylinder block in place and all the mounting holes line up fine so bolting that back in should not twist or distort the frames.

The remainder of the stretchers etc fitted to check alignment

Whilst I'd got the camera out I took a photo of the port face on the inside cylinder block. The ports are well machined but there is quite a bit of wear on the port face. I'll lap it on some fine carborundum paper on the surface plate to level the surface again.

Nicely cut ports on the inside cylinders

The two short pipes take the exhaust through the steam chest walls and into the steam chest cover.


A bit more progress made over the last couple of weeks. I've stripped the old paint off the wheels and removed the old crankpins. The spigot that fits into the wheel boss on one of the front pins had been made very oversize for some reason (perhaps the hole on the boss had been drilled in the wrong place?) and had been rivetted over on the back of the wheel. The only way to get it out was to drill off the outer end of the pin and then drive the spigot out the back of the wheel. The two long driving wheel crankpins passed through the wheel bosses and had nuts fitted on the back for some reason. A closer inspection showed that one of the wheel bosses was actually cracked in three places around the crankpin and this may be the reason for the nut on that pin. It looks like the pin had been made too tight a fit when pressed in causing the boss to crack. This is very easy to do with press fits if you are not careful, especially with cast iron which is very brittle. Fortunately, the wheel seems solid enough and I'm hoping that it will be ok with a new crankpin Loctited in. I also noticed that one of the wheel flanges has been repaired at some time and must have had a piece chipped out at some time.

I've decided that the play in the two front axles/axleboxes is acceptable and it is not worth the hassle of trying to press off the wheels and bush the boxes. Removing the wheels from the crank axle would be a bit tricky anyway and may do more harm than good!

I've made a new axle and axleboxes for the trailing wheels and at the suggestion of fellow club member Dennis, have drilled the axle ends and put a cross drilling in the centre of the axle boxes. This will allow oil to be squirted into the bearings from the outside now and again to flush any grit and ash out of the bearings. However, when the time comes, I intend to fit a shield of some sorts to try and stop the ash getting to the bearings in the first place. As they say, prevention is better than cure!

I've also turned up and fitted new silver steel crankpins with Loctite.

New axle and axle boxes made for trailing wheels and new crankpins fitted

It was when I fitted the crank axle in the frames and spun the wheels that I noticed one wheel was wobbling violently! A close look revealed that one of the crank webs was loose on it's crankpin and could move. Aaah! this gets worse!!

The crank assembly appears to have been brazed or silver soldered together and it looks as though the spelter or solder has not penetrated through the joint and only formed a ring on the outside. This has obviously fractured over the years resulting in the looseness. A close inspection revealed what looks like a pin in the offending crank web which suggests a repair attempt at some time. None of the other joints show any sign of pinning. What to do?

I decided the easiest way out was to drill the web and the crankpin again and fit another pin at right angles to the other one. This would prevent the web moving in the direction causing the problem which was vertically through the web. The web was drilled vertically right through the crankpin and into the other side and reamed to take a 3/32" silver steel pin. A flat was filed on the side of said pin, the pin coated in Loctite, and then driven in. The flat on the pin was to let the excess Loctite escape. This seems to have done the trick as the crank is now solid.

At this point I thought it would be a good idea to check the quartering of the wheels to see if there are problems there. To do this I mounted the wheels between centres and rested one crankpin on a length of bar sitting on the cross slide. A dial gauge was then mounted in the lathe toolholder and wound in to touch the other crankpin. I then noted the reading on the cross slide dial when the dial gauge indicated a certain reading. This reading should be the same for all the wheel sets if the quartering is all the same. At this point I had not fitted the trailing wheels to the new axle so could only compare the front wheels and the driving wheels.

The setup to check the wheel quartering using a dial gauge on one crankpin and a vertical bar on the other

As expected, there are very slight differences between the two wheel sets but only a few thou so I'm hoping this will not cause major problems. It will just mean allowing a bit more clearance in the coupling rod bushes (fingers crossed!)

Using a similar set up, I Loctited the trailing wheels onto their new axle. To set the position of the crankpins I replaced the dial gauge with a piece of bar. This was set in position using the driving wheel axle and then used to set the position of the trailing crankpins before the Loctite went off. There is not much time to do this once the Loctite is applied and the wheel pushed on!

Setting the trailing crankpins after Loctiting

I'm now waiting for some 7BA csk screws to arrive when I can start bolting the chassis back together.


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