Wheel Drops

At the firebox end the boiler sat on angle brackets riveted to the firebox and resting on the top face of the frames, so was free to slide as the boiler expanded and contracted due to temperature changes (wide firebox fitting was slightly different). But it was restrained in the vertical direction also so the boiler could not lift at the trailing end.

 

Plus the fact that shear legs could be comparatively easily taken down and erected elsewhere, whilst digging abloody great big pit and then installing equipment would be considerably more expensive.

 

The MHR has one. Ex-Bricklayers Arms, which was significantly modernised in late SR days.

On another note, a one-time colleague of mine commented once on the oddity that nobody ever questions propping something on big wooden blocks, whereas with a steel frame every man and his dog wants to see the design calculations.

 

Modes of failure perhaps?

 

Ah, but big wooden blocks tend to be just that, and provided the load isn't along the grain, are pretty good in compression. Steel structures, on the other hand, are built up and as well as struts and ties, they need fastenings. All are usually designed to use the minimum possible materials, so the strength factor needs to be proved.

 

We used to prop 75 ton steam turbine cyliners up on oak blocks. The blocks did not even creak. In my 1942 edition of the Machinery's Handbook it has permissible working stresses for various timbers. For oak in compression it is 900 psi for stresses parallel to the grain, so a design calculation is not too difficult. A 12" square should therefore support 57 tons if it is in good condition without defects. I do not know if there is more modern information which changes these values

 

[off topic]And yet still people insist "they" will never allow a new wooden underframe for a vintage carriage body. [/off topic]

 

GCR has the rusting remains of a wheel drop somewhere. They sat in Loughborough yard for years, then more recently were loaded onto a well wagon but have since been unloaded from it, I'm unsure where the bits are now. I'm not sure if it's complete. Maybe one day...

 

Sorry to go [off topic] But talking of things sat on the GCR, what happened to Workington Shed? [/off topic]

 

most of it forms a rather large rockery at the back of swithland sidings.

Colin

 

In the world of structural engineering an oak beam has better fire strength than the equivalent steel beam.

 

I'm sure if you make your new carriage a solid wooden block with no room for people in it "they" will happily allow it.

 

Oh, I'm perfectly happy with the appropriate use of big wooden blocks, absolutely essential for a lot of propping and assembly work. But it's amazing how infallibility is conferred upon the engineer who is seen shepherding a flock of oak blocks and strange looking plywood pieces towards the job, muttering about corbel arches and generally making it up as they go along, as compared to the one carefully designing fabricated tooling which can be proof tested in advance, who must surely have made some mistake and must be rigorously checked.

I have been both of those engineers at various times...

 

I believe the Isle of Wight Steam Railway has a wheel drop.

 

The WSR have one as yet not installed. Its is not ex BR though and is of fairly recent manufacture IIRC.

 

Yes it has although it must be regarded as being a rather rudimentary one.

 

There is some midland pattern sheer legs at Barrow Hill. I dont think they are in use though, seems some of the parts are missing http://www.barrowhillcollections.com/sheerlegs/4587539324

I suppose the advantage of sheer legs is that they can be used to lift other stuff and also parts onto an engine etc, whereas a wheeldrop can only be used to drop wheels. As for wooden blocks, at least they cushion the load a bit.

 

The BR western region shed at Southall had a wheeldrop in its own building that's still there. It was used in 2013 (if I remember rightly) to remove driving wheelsets from Union of South Africa.

There was a period where the shed was occupied by the GWRPG, and I remember a few of the more mischievous members working out if they could hide their Peckett under the floor!

 

Two surviving operational wheel drops in former steam sheds are those at Carnforth (10A) and the NRM at York (50A).

Peter James

 

I'm sure you're on the right lines.
In the 1930s, the LMS invested £75'000 in shed improvements including coaling plants, pits, wheel drops, etc., a collosal sum for the times. They also reorganised their maintenance regime.
It paid off in getting locos to spend more time in service and less being serviced and shopped, improving engine-miles per day per loco from 95 in 1929 to 118 in 1936. This meant they got 25% more work per loco, and could reduce loco numbers by 25% between 1923 and 1936. Meanwhile 'casualties' (unscheduled stoppages of engines) reduced by more than 30% between 1934 and 1936 alone...!
Although Josiah Stamp oversaw the main period of implementation of all this, the initiative partly predated his appointment, and were a marriage of Midland and Caledonian ideas.