4mm Wantage Tramway - Matthews Tram Engine (EM)

Discussion in 'EM/S4 & S scale' started by chrisb, 25 December 2016.

  1. chrisb

    chrisb Western Thunderer

    I was recently asked to undertake a commission to build the Wantage Tramway's Matthews tram engine. To be honest, I'm not much of an engineer and would more happily spend my time working on the scenic side of things but a quick bit of research revealed Worsley Works produces a very inexpensive etched kit in 4mm scale for the tram engine body and, given the presence of side skirts on the prototype, I realised I wouldn't need to perform any scratchbuilding heroics to create the chassis.

    So I accepted the commission only to subsequently discover the customer expected the chassis to be built as close to the prototype as possible.

    Well then, after a large intake of breath, here goes...

  2. Obblygobbly

    Obblygobbly Active Member

    Good luck with the build. I will follow this with interest.

    I would love to know where you could find enough information on such a rare loco to make an accurate model. Apart from the chassis, there must be quite a lot visible through those windows.

    At least there is some info about Hughes tram locos to help guess what No4 may have been like in detail, but No 6 was a one-off, I believe.
    David Varley likes this.
  3. Overseer

    Overseer Western Thunderer

    There are quite a few photos of No 6 as it lay around for many years. I am in Myanmar at the moment so don't have access to info but from memory it was an outside framed 2-2-0 with near circular outside cranks. Hardly seems worth building it all when it will never be seen, especially in 4mm. But good luck and I will be interested to see progress.
  4. chrisb

    chrisb Western Thunderer

    Thankfully (and no doubt how the customer knew so much about the tram engine) there is an excellent article written by Jack Meacher in issue No. 36 of Railway Archive which provided me with the basic dimensions and arrangement of the 2-2-0 chassis.

    Wagonman and AJC like this.
  5. chrisb

    chrisb Western Thunderer

    Being a 2-2-0, the chassis is relatively straightforward and I felt I could put it together fairly easily using available parts and spares - except for the odd-sized disc cranks (the purpose of the smaller crank on the leading axle is a bit of a mystery.)

    Manufacturing these cranks is something well beyond my skillset (not to mention my toolkit), but thankfully Steve Cook kindly came to my rescue and agreed to make the cranks for me:
    AJC likes this.
  6. adrian

    adrian Flying Squad

    Sorry I'm not quite following this - if it's a 2-2-0 what is the purpose of the crank on the front axle at all i.e. irrespective of size. I presume it's inside valve gear as it seems that the valve rod/radius arm is curved over the front axle.
  7. Scale7JB

    Scale7JB Western Thunderer

    It probably is the valve/connecting rods.

    It's definitely a concept used on a number of engines. On some the rods will have a complete loop passing both over and under the leading axle.

  8. adrian

    adrian Flying Squad

    I have seen it before with the rods passing under and over the leading axle so that's not a problem - it's the crank on the leading axle that is puzzling me as to it's purpose.
  9. Scale7JB

    Scale7JB Western Thunderer

    It could be some kind of a water pump? Can't think of the technical term for it at the moment, but traction engines have similar on the main crank.

  10. chrisb

    chrisb Western Thunderer

    Jack Meacher admits (in the article mentioned above) that it's all a bit of a mystery - "The purpose of this is a puzzle...Perhaps there was some (unseen) constraint as to why...".

    If you're really interested there's a lot of information in the article but basically the Matthews patent documents show a more conventional 0-4-0 arrangement with equal-sized disk cranks on both axles whereas photographic evidence (specifically H. C. Casserley's print No. 6596) shows a mechanism that was anything but conventional - the wheels were inside the frames with the cylinders, valve gear and steam chests outside the frames. The radius rod that you mention can be seen in Casserley's print curving over the front axle outside the frames and it appears to be manufactured from flat plate.
  11. adrian

    adrian Flying Squad

    I thought that axle pumps were more commonly driven by an eccentric rather than a crank drive, also I would expect that they would be driven from a powered axle. If it's a 2-2-0 then the front axle is not powered so I'm surprised that anything would be driven from it.
    The only thing I can think is that it was originally built as a 0-4-0 but for what ever reason the coupling rods were removed to make it a 2-2-0.
    Isambarduk likes this.
  12. Obblygobbly

    Obblygobbly Active Member

    Could it have been just some kind of retaining device for the axle?
  13. Scale7JB

    Scale7JB Western Thunderer

    Are we definitely sure it isn't just a bearing that's being shown? It's not particularly clear I know..

  14. Stevesopwith

    Stevesopwith Western Thunderer

    The 1879 Matthews Patent drawing, in Vol 1 of David Gladwin's 'History of the British Steam Tram', includes a plan, as well as the side view used to produce the drawing above.
    As Chris says, the wheels were inside the frames, while outside, in order, were the valve eccentrics, equal sized crank discs for each axle, the coupling rods, and lastly, the connecting rods. In service on the Wantage Tramway however, the coupling rods were removed, (as was also the case with the Hughes Loco). Photographic evidence indicates that the redundant forward crank disc was also removed. The drawing doesn't show a " smaller crank on the leading axle", its the original disc and crankpin.

    I'm assuming the original patent drawing has had 4mm model related additions, ie. the larger than scale wheels, with a modified frame outline to suit, so the rear yellow disc is appropriate for a somewhat enlarged crank disc. However while the forward yellow ring might represent the front axle stub, there shouldn't be a crank or anything else on the end. The ring would be appropriate for the model's front axle bearing, as JB suggested.

    There is one 'in service' photo showing the loco with it's side panels raised, probably for a bit of attention; all the many other photos show it running with the side panels closed, so I am inclined to echo Overseer's reservations, although I too have considered a similar arrangement when I build my second, upgraded version of this loco in 7 mm, because I can, and I'll know it's there. :)

    Incidently, for what it's worth, I believe the Worsley etches incorrectly include a boiler tube access panel at both ends.

  15. Stevesopwith

    Stevesopwith Western Thunderer

    Having checked my sources this morning, I'd like to make a couple of corrections to my earlier post.

    I found two more photos, probably taken on the eve of closure of passenger services in 1925, which show No 6 at the platform with the front right hand side panel raised. I don't think there would be enough clearance to open it between the platform face, so I assume it must have at least entered the train shed with it already open. That said, it did usually run with the panels closed.

    I also found my copy of the Casserley photo of No 6 posed with the panels open, ( I should have done it last night ) ... and I have to admit that I see what Chris was getting at with the small yellow ring. Under magnification it is possible to make out the ends of both axles, with a small disc on the front one, corresponding to Chris' drawing. It does not appear to have a crank pin or anything else to explain it's function.

    I wonder if it is the remains of the original crank disc, that has been turned down, removing the portion supporting the crankpin, allowing improved access to the valve gear, while retaining the axle and hornblock alignment. Whatever the explanation, I now think Chris is correct in his proposed depiction of this detail.

    I apologise for my rather hasty earlier comments. :oops:

    Happy New Year to everyone! Steve.
  16. chrisb

    chrisb Western Thunderer

    Yes, that's correct. The side skirts are also incorrect in that the toe-hold step is at the same end on both sides whereas on the prototype they were on opposite ends (and sides of course).

    Luckily neither issue is a problem. For the ends, one etch can be reversed (i.e. the side with the etched access panel will face inward rather than outward so that the blank side is shown.) One of the side skirts can also be reversed and while that will hide the etched detail for the side access panels, I'm making working hinged access panels anyway (which will also ensure that the effort put into modelling the motion won't be hidden/wasted) so the etched lines will be redundant.

    As an aside, the Worsley etches are, I think, very good value despite these errors.
    Isambarduk and Steve Cook like this.
  17. chrisb

    chrisb Western Thunderer

    Some progress photographs of the chassis:

    IMG_7109.jpg IMG_7110.jpg

    The gearbox (Horizontal MicroMiser/108:1) and hornblocks are from High Level, the wheels are Alan Gibson.

    Being so tiny weight is an issue at present (in the first photograph you can see how the pickups are pressing on the compensated axle and causing the rear of the chassis to ride up) but I plan to replace the brass pickup wires with finer phosphor bronze wire and to also mount the boiler and water tanks on the chassis which will give plenty of opportunity to pack in some extra weight.

    The next task is to mount the supports for the motion on the outside frames and then permanently mount the frames to the chassis.
  18. Matt.S.

    Matt.S. Member

    is this not an ideal candidate for split axles?
  19. chrisb

    chrisb Western Thunderer

    An embarrassingly long time since the last update but progress... IMG_9064.jpg

    It looks much larger than it is - not only is this a close-up but the photo was taken at 2x magnification.

    Apart from the disc cranks which Steve Cook kindly made for me, the motion has been cobbled together from bits and pieces in my spares box. I need to add some bolt heads and could add more detail but when the body is mounted it will be hard to see.

    The body is almost complete with a little more detail still to be added, primarily the chimney, the wooden buffer beams and couplings. The water tanks have been fashioned from styrene sheet and I'm waiting for some resin rivets before they can be completed.
    Dave, decauville1126, Simon and 8 others like this.
  20. chrisb

    chrisb Western Thunderer

    Current state of play showing the "skirts up" side after an initial coat of primer:

    The water tanks look a bit wonky but haven't yet been fixed in place - still waiting on the resin rivets in order to complete them - but they do a great job of hiding the mechanism and the DCC chip which is sitting on top of the motor.