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Gwr 'Mermaid'


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  • RMweb Gold

Whilst tidying the model room today I came across a part built Cambrian kit for a BR Mermaid ballast tipper.

 

Now I understand that the BR prototype is based upon a 1930s GWR design, which has left me thinking about converting the kit into something more useful.

 

I am interested to hear what differences there are between the two types.

 

So far after looking at photos I can see that it will need 2 shoe Morton breaks, along with different buffers.

 

Comparing photos I was wondering if there is a slight difference with the ends?

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Now I understand that the BR prototype is based upon a 1930s GWR design, which has left me thinking about converting the kit into something more useful.

60 Mermaids were purchased by the GWR from Metro-Cammell in 1930. No official GWR diagram was issued. They had single-sided Morton brake gear.

 

 

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Thanks, I think I will have to hold on any more building until I can get a copy of Russell, unless I manage to find something on the internet... Does the Russell photo show the end of the wagon?

 

Further reaserch seems to indicate that the mechanism for controlling the unloading is different on the gw, (I understand it's a much larger ratchet)

 

Under the sole bar shouldn't be to difficult to work out, and the Paul Bartlett photo shows the Morton breaks clearly.

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The ends might need a bit of modification if I find a clearer photo, but here is the almost completed wagon.

The body has a little damage (it was built over ten years ago and left in a box...), I'm tempted to bin it and replace with a new body, but will see how it looks once painted.

 

Chassis wise I removed the mountings for the breaks, along with the vac cylinder and the v hangers. New single side Morton breaks were fitted (park side I think from the bits box) with some etched brass v hangers (dc kits again from the bits box). New buffers complete the chassis along with a couple of lengths of brass rod.

 

Under the body I have fitted a lot of lead sheet to add some much needed weight. It still needs break leavers, however I have not got anything suitable which matches the distinctive shape.

 

Photo below showing it alongside a Kirk ballast wagon who's diagram escapes me (which uses leavers from the parkside spur I used on the mermaid

post-54-0-26984700-1390340202_thumb.jpg

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Hi Rich,

 

Interesting to see someone having a go at one of these wagons.  I made the moulds for this kit some thirty years ago when working at Cambrian.  We had a copy of the BR Diagram GA drawing, but did also  refer to  the Jim Russell book as mentioned above.  I had assumed that the GWR batch were to  the same design as the BR ones apart from the brake gear and buffers, just like the GWR designed Tunny in your picture having been the basis of the later BR-built Grampus (with the addition of drop-ends of course). 

 

Presumably the GWR Mermaids had the screw-coupling type rail clamps on the solebars fitted from new.  The clamps stopped the wagon tipping as it discharged its load, but tipping too many wagons at once would have pulled up the track they were standing on. 

 

All the best,

 

Colin

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Hi

 

Stephen Harris does a kit in 2mm for the Mermaid and both the GWR and BR versions can be built from it. There are no obvious body differences but it is supplied with parts to build two different chassis with brake levers.

 

Cheers

 

Paul

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Presumably the GWR Mermaids had the screw-coupling type rail clamps on the solebars fitted from new.  The clamps stopped the wagon tipping as it discharged its load, but tipping too many wagons at once would have pulled up the track they were standing on. 

 

All the best,

 

Colin

No sign of the rail clamps in the photos in the Tourret bible.

 

The ends look very similar to the BR ones either side of this http://PaulBartlett.zenfolio.com/brmermaid/e1ce7881c

 

Paul

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Back in the day when in the old brown brittle plastic it was a fiendish kit to make................ :O

The Ling I've got went together quite well; however, a couple of minerals of the same vintage crumbled as I took them off the sprues. Would this have been 'oil crisis' polystyrene of 1973 vintage, I wonder?

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The 'flat-bottomed' ballast is a P19 or P21 'Ling' as in these photos:-

http://paulbartlett.zenfolio.com/gwrlingzco

It would be nice if this model were to reappear; I wonder who took the moulds over for it?

Oops!

 

Forgive my mistake as the GWR 14t  LIng and 20t Tunny were very similar, with the latter having slightly higher sides.  Chivers make the GWR Tunny, but it is from (relatively) new tooling.

 

All the best,

 

Colin

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The Ling I've got went together quite well; however, a couple of minerals of the same vintage crumbled as I took them off the sprues. Would this have been 'oil crisis' polystyrene of 1973 vintage, I wonder?

Hi Fat Controller,

 

I can't comment on those specific kits and why they were brittle, but when I was involved with Cambrian (now Cambrian Models) it was quite easy to 'cook' the polystyrene. 

 

This was sometimes the result of overheating of the mould during a lengthy moulding process, or from working the moulding machine with a higher temperature to  get the plastic to flow into the smaller cavities of the mould (but too hot = flash).   The Mermaid is a case in point, as it had many fine parts on the sprue.  The other means of filling a mould would be to increase the pressure on the plastic to force it in.  We only used a manual moulding machine plus one with an air-ram for filling larger moulds.  It was all a matter of touch really with the manual machine. 

 

Some manufacturers, such as Chivers, use thicker cavities and larger gates (the bit between the sprue and the component cavity) to ensure reliable filling of the mould without running the machine too hot. But you could be right in saying the brittleness in the case of your kits was down to the grade of plastic: I know that my brother now uses a more durable grade of styrene granules which is less likely to 'cook' and can be used  at a higher temperature.

 

All the best,

 

Colin

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Thanks again to all, a very interesting look into the moulding process there.

 

As for my model it's now sat awaiting paint, far to tired to contemplate that any time soon.

 

In the meantime if anyone finds any other photo showing the lettering / gw logo position that would be very welcome.

 

Would be a nice addition if Cambrian could tool up the gw under frame and offer as a kit..

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  • 9 months later...
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As far as the research shows its only tge differences described in this thread

Not major work at any rate.

 

My plan is to follow this one up with 3 or 4 more

 

Though I'm still short of photos showing the logos.

Hopefully I will soon find a reasonable priced copy of the Russell Gw wagons and loads book.

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