Izzy

A GE area Class 21 in P4 - updated **** Some years back now Dapol finally got around to producing a NBL type 2 later known as the Class 21. It was I believe 10 years between announcing the intention to make a 21/29 and when they actually arrived. In the end I wonder if this was no bad thing because they are to my mind a really nice loco and a world away from the previous class 29 produced by Hornby back in the 1980’s which I converted a few of to P4 over time. One of the original early diesel classes they used MAN engines produced under licence by NBL and were found wanting, being highly unreliable. At first located to Hornsey for North London commuter services they were soon moved to the exGE area and stationed at Stratford and Ipswich before being moved to Scotland in 1960 reputedly to be nearer the NBL works in Glasgow for all the warranty work they needed. Although their stay on the exGE lines thus turned out to be quite brief, 12-18 months, I thought it might be nice to add one to my loco stock as their size means they are a nice alternative to the class 15 and 24 I have and were mostly used on light local duties once the extent of their problems became clear, those of them that could be coaxed into life. Since the Dapol model arrived there have been several postings on different forums on the ways they might be converted to P4. These are: machining the wheels to reduce the flanges. Machining the wheels and fitting new steel tyres to P4. Replacing the wheels with Gibson tender wheels and drilling out the gear muffs to take the 2mm axles along with fitting wiper pickups. Having read all these I hesitated over getting one so it was only recently, four years after they reached the shops, that I finally decided to chance it and obtain one. I have to say that I’m now very glad I did, but that the experiences gained with converting my other diesel locos has come in very handy. My conversion started with an almost complete strip down to remove all the electrics. They are fitted with lights with options for different settings when fitted with a 21pin 6 function decoder on DCC. There are also four switches on the bottom of the fuel tank for DC users. As these class 21’s had disc indicators and I never use lights on my models all this is surplus to my requirements so I chose to remove it all and fit an 8-pin socket so I could plug in whatever decoder suited my needs. The intention was to fit a sound install but with different decoders available to test the loco with while the conversion went on this seemed a sensible course to take. All the wiring connections are via plugs on the circuit board. Most parts are screwed together. The fuel tank screws in place and removing it allowed the switches to be taken out after unsoldering the wires. Once the only wires left were the track feeds from the bogies and to the motor tags I replaced the plastic top plate and fitted the 8-pin socket to it. This was a home brew affair using a piece of pcb. There is plenty of room to fit a large speaker, 40mm x 20mm, and leaves loads of room for a decoder and stay-alive should you desire the latter. I have not found one necessary. Removing the cabs should you wish to fit a crew is difficult. You need to remove the lighting bits that plug into the cab fronts to allow it’s removal and in doing so the lights which plug into the moulding can break off. This is the only poor bit of design I came across. So, now we come to the actual conversion to P4. As this just (!) involves the wheels/axles in the bogies removing the latter from the chassis is not needed and can be accomplished by removing the outer bogie frames which clip into place on the inner gear towers. However ‘clip’ is a bit of a misnomer. They do clip into place, but are so tight that getting them both off and then back on requires a considerable amount of force with a jewellers screwdriver. You need to be very careful because there is a considerable amount of detail on these bogies, brake details and sanding pipes etc.. all individually added and breaking some of it was always my fear. With luck nothing was damaged but a lot of care was needed to ensure this didn’t happen. The bogies use split axle current collection. Nice nickel-silver plated cast mazak spoked wheels with shouldered steel stub axles running in brass bearings with a central plastic gear muff. Having a lathe my decision was to first see if conversion was possible by machining the wheels to both thin the flanges and reduce their depth, so they would pass through P4 flangeways. This I found was indeed possible to achieve, the stub axles being drifted (tapped) out of them and the wheels mounted on an arbour to ensure concentric turning. As the flanges were about 0.9mm deep and wide taking 0.5mm off the rear brought the flange width down to around 0.4mm and 0.4mm off the diameter left the depth at 0.5mm. After machining they were dressed with a flat needle file while spinning in the lathe to round off the edges. As the front faces of the wheels are nice I left the overall width alone, which had reduced to 2.4mm. Running behind the bogies they aren’t really very visible at all although at low angles the spokes of the wheels are just about seen. I guess you could almost get away with using plain disc wheels if you needed to. To get the wheels remounted at the right btb of 17.7mm I left the stub axles about 0.5mm out of the wheels when I refitted them and also left them about the same distance further out in the gear muff. The stub axles were an interference fit in the wheels and a tight push fit into the muffs so no gluing etc. was required. The end result is a nice, smooth, and quiet running loco. Currently a sacrificial TTS class 31 decoder and speaker have been fitted to test the loco out while a decision is made with regard to a proper sound install via a Zimo or ESU setup. Enquiries have been made. Once finished it was discovered that the fine etched fan grille on the roof can be seen through at certain angles and the speaker inside then seen. So as no fan was fitted beneath one was made up in plasticard and installed. It was painted red but isn’t as visible as with other models that have them. All it’s needs now is to be weathered to match my other rolling stock. Not too much because they never worked enough to get very dirty. Hope this is of help and interest for other Dapol class 21/29 owners Bob

Interesting to see the design changes that have happened in comparison with previous bogie diesels where the basics have remained virtually unchanged from the early Farish onwards. Not only the brass bearings but the two stage reduction and offset gear chain. Similar to the Bachmann American diesel bogie designs. Many thanks for posting the details, very helpful. Bob

A quick look on the web brings up SEERS (South East Essex Railway Society), a railway club/society local to Leigh. There is also Shoeburyness Model Railway club. Perhaps someone from either knows your grandad. Contacting either would seem to be the best course of action. Bob

That seems a good idea. As mine have been all bespoke installs I could do them separately and then add them together afterwards. Or you could just give the new decoder a different address until setting up is complete and then change it to be the same after. Would save any future consist issues that might arise Bob

Oh, so it’s another stunning layout on the horizon? Something else to look forward to then. Bob

You may be a trailblazer with this one Pete… go on, you know you can 😁. A 128 on Mortonhampstead, well fancy that! Bob

To avoid this kind of issue with droppers I always bend them at right angles so they lay flat along the underside of the baseboard and after soldering on the wires tape over them to assist in holding them in place without the danger of the joints breaking under strain. Bob

Yes, will be a case of disconnecting the wires to the motor, I presume it won’t be hard connections through the chassis for that aspect but just for current collection, and then adding ones for the extra decoder along with feeds. This always presupposes there is space to fit the second decoder on top of the existing board with appropriate insulation. Bob

I've done similar in the past with the early TTS decoders, using basic Zimos for the motor control and the TTS for the sound. This is with diesels and worked okay until I could get around to fitting decent sound installs on Zimo and ESU both of which have much better motor control. Obviously you have to give both decoders the same address so conflicts with Functions have to be avoided such as extra lighting etc. Since I only wanted motor control and sound fuctions all was well. Worth a try I would say although with a built-in sound system trying to separate out the motor control might prove awkward, would depend on the whole loco design I guess. Bob

I don't know Simon I have no knowledge of the design. It's really mostly about the rear bogie and the total end swing such long locos have, remembering they are Pacific locos back-to-front. So how much side play the middle and rear drivers need in conjunction with the bogie movement. Easy if you treat the pony truck and bogie as free apendages and just rely on the six-coupled drivers to do all the guiding, but that rarely gives good results and allows the front/rear to swing about with wanton abandon which doesn't look good. Bob

Thanks Ian. I've used several of the Shed Bash UK lists to try and pin down suitable locos. Those for not only Colchester (inc Clacton/Walton), but Parkeston, Ipswich, etc. The trouble is the lists don't always match up with the info on BRdatabase and that then makes me wonder how accurate any of it might be on either site, though wonderful resources both are in general. There is also the shed allocations on the GER society modelling pages for the early diesel era which is equally helpful. Bob

Ha, I like your optimism Simon! I did have a plan for the L1 and various etches gathered together to assist but every time I look at it I wonder if I have the mental energy and desire to push myself to make a start on it, trying to visualize how I will tackle it and the issues that could arise with particular aspects. Getting it around tighter curves is a prime consideration and experience suggests it will need a bit of thought to get the result I want. Bob

Henkel make Multicore rosin solder in both lead free (Green label) and Leaded 60/40 (Red label). I only use the latter which is available in reels from a range of suppliers. My last reels came from Axminster tools as they were miles cheaper than anywhere else at the time. Bob

…and also clean the toilet and rot your teeth….. I also use dilute phosphoric acid. Just not sure where you would get it these days. Mine came from Boots back in the ‘80’s when it was a proper chemists, a 500ml bottle I reduce down to 15/20% - quite strong. I’ve used about half so it should see me out…! Bob

Ah thanks Angus, I hadn't appreciated the difference between the two models before. Your dead right the turnunder is part of the look of the loco and I recall there was a lot of debate over the Dapol 4mm model in the early design stages when it wasn't correct. I'll certainly follow your lead with that. Bob