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BR Shunting Locomotives - Class 12
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A total of 26 SR / Bullied designed 0-6-0 diesel electric shunting locomotives were built
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ModelRail / Heljan Class 12 - EM Conversion Notes
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by 1952 at Ashford Works for use on the Southern Region of BR, all being withdrawn by 1971.
Class 12 - 15221 shown straight from the box with the crank pins and rods removed. An
easy job on this version of the model.
It would appear that some variants of the ModelRail / Heljan Class 12 are produced
differently, with some having the crank pins applied with a thread-lock
compound. The green 15221 models with red rods are easy to dismantle, whilst the Tilcon blue
examples with black rods have tight (and easily broken) crank pins, with evidence of
thread-lock compound after removal. The rods have been factory fitted with little regard to
their orientation, the knuckle needing to be at the cab end. One silver lining in the case
of these 2 models is that one has 2 left hand rods, whilst the other has 2 right hand rods.
Alan Gibson crank pins have been used to replace the broken set, although this did involve
broaching the holes on the rods to accomodate the crank pin bushes.
As with the Class 11 wheelsets shown here in the lathe, the Class 12 conversion to EM gauge
benefits from having 0.5mm faced off the back of the wheel, resulting in each wheel only having
to be moved 0.5mm on the axle to EM gauge so that the completed wheelsets fit nicely back into
the frames. This method of using the existing wheels doesn't require removal of the cranks,
keeping the quartering intact.
The sand pipe bracket which is secured inside the frames, fouls on the rear wheelset due to
the 18mm diameter wheels (not a problem with the 16mm wheels on the Class 11), so the bracket
needs to be cut short and glued onto the underside of the frames for clearance. This view also
shows a tie bar secured to the cab footsteps on the Class 11, as they are unsuported and too
easily broken off (several times being clumsy).
Correct height comparison between a Hornby 08 and the ModelRail 11 & 12. The Class 11 has 4'
driving wheels and is 3" lower than the outer two that have 4'6" driving wheels.
