Friday 22 November 2013

Railcar glaze and turntables

 Work on the railcar continues apace. Basic box complete, floor in and Kato chassis temporarily  clipped on. Next problems are rigging some seats up and working out how to glaze it. The DHLR had no partitions and a central motor with underslung rad' so a fairly clean machine will result.
A second view of Bembridge with the swivelling plate end. Question: If it is pivoted in the centre, but doesn't turn 360 deg is it a turntable or a sector plate and why?


  1. Hmm. A very good question - which like all such deserves a very good answer.

    [1] As it does not turn through 360 degrees it is not a turntable.

    [2] If it pivoted at the end it would be a sector plate - the shape through which it moved would be a sector of a circle. That is to say the area within a circle between two radii and the arc (the relevant part of the circumference) joining them. I simple terms it is like a piece of pie shape.

    [3] However, that would only apply if the pivot point was at one end. As it is in the middle each end of the plate would move through an identical but different sector. Does that make it a "double sector plate"? Or would that imply two tracks on the plate?

    [4] Sometimes there is no simple and quick term to describe something accurately and seeking such may be a waste of time. Therefore might it not be called - "a centrally pivoted sector plate"? Not I grant short and snappy, but it is clear and self explanatory.

    Christopher Payne

  2. Turning plate? Sector table?
    I don't know whether the prototype table at Bembridge was used to turn locos or not.
    Pretty sure there weren't any tender locos used on the IoW, you wouldn't usually need to turn a tank loco and space doesn't seem to have been at a premium so why was there a turntable there at all? Perhaps someone thought it would confuse railway modellers in 150 or so years' time.
    I don't think I have got any books on the railways of the IoW so perhaps a visit to the library will shed some light.

    There is a plan for a micro-layout based on Bembridge in one of Paul Lunn's books, I have thought about using it as a basis for something French so my Michelin rail bus could be turned around. Brassac had a similar arrangement with a railcar shed on the other side of the turntable.

    It is an attractive arrangement for a layout even though it was rare in reality. I seem to remember one of Don Sibley's narrow gauge layouts having a small turntable that served as both engine release and access to the loco shed......a lot of space saved with a small turntable doing the work of several points.

    If you wanted an easy solution, the PECO H0m turntable could be used as it has an optional solid top, C&L chairs or PECO Pandrol clips then being used to lay rails to the desired gauge.

    Simon H.

  3. As far as I'm aware the 'swivelling plate' at Bembridge was an proper turntable although never used as such. In actual fact, if a loco was standing on it there wasn't clearance between the loco buffers and the platform end/fence etc. to turn completely around. It was installed for space reason's because immediately beyond the end of the turntable was a main road, so there was no room for a set of points and a headshunt. There used to be another example at Ventnor, although this was later replaced by a conventional (but very cramped) headshunt). As Simon says, the IOW was a tank engine line, so no need to turn loco's.
    Incidentally, did any British 'Real Railways' use Sector Plates, or are these a space saving invention of modellers?
    And....what was the sideways moving plate at Birmingham Moor Street called?

    Graham W

  4. Erm. I seem to have answered the original CF question. Interesting as the above answers from Si and Graham are, I suggest they have not. Unlike self to be direct and to the point - but there you are = exception that proves the rule.

    The Don Sibley layout that Si refers to is I methinks "EL TORTUEGO" (yeah I may have the spelling wrong without looking up the relevant CM article - apologies).

    Christopher Payne

  5. My thanks to the above. My question was possibly two-part 1. turntables and sector plates the difference of. and 2 How this applies to the example shown in it's prototype form.
    Graham answers the question (and Simon's sub question) to whether the Bembridge plate was used for turning and clarifies that it was not. This is useful purely as it suggests that even though not for complete turning it is designed as a centrally pivoted table - one supposes because of 'balance'.
    CP gives the technical answer, but in 1. states 'not a turntable' However in this example one presumes that as it is capable of 360 deg that it is and was not used thus because of loco swing, and not because the 'plate' could not do so.

    GW's comment that sector plates may be more of a model term is probably nearer the mark - the IOWR refer to this and the Ventnor plates as 'turntables'.
    So taking all that on board: sector plate - end pivot, turntable -central pivot, but does not necessarily need to turn 360 deg in operating to qualify. The defining item is the pivot.

  6. CF says - "The defining item is the pivot."

    CP says - "Is it?"

    [1] Would it not be better to say that the defining item is the MOVEMENT about the pivot?

    [2] In other words to ask if the movement is rotational or simply pivoting back and forth.

    [3] Not that I suggest these terms are appropriate for a turntable, sector plate, whatever, but is not the distinction somewhat like that between movement about an axis that rotates or oscillates?

    [4] And should we be considering what the "moving table" (for want of a better neutral phrase) does OR the locomotive upon it.

    [5] I would also suggest we consider common usage of the word "turn". It is of course confused - for on the one hand we speak of a 360 degree rotation as being "one complete turn", but on the other of "turn (a)round" and "about turn" as being only 180 degrees.

    [6] And locomotives aside what about "wagon turntables"? No doubt there are all sorts of examples that either prove rules or prove to be the exception to them. Typically, however, did they not function to turn a wagon through 90 degrees for example to allow it to enter a warehouse or similar premises alongside the track. And that said was not the table capable of further rotation.

    [7] Bearing all that in mind (and perhaps despite the "wagon turntable") would it not be fair to say that to qualify for the name "turntable" the movement of the table about the pivot should ideally be at least 180 degrees.

    [8] Finally is not the real issue how such items of machinery can be described accurately and without confusion? Therefore, and yet again arguing that short snappy descriptors are not necessarily a good thing, it would still seem to me that "centrally pivoted sector plate" achieves that end.

    Christopher Payne

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