In a wood near Ilkeston in Derbyshire, there is a large earthmover and trailer that were deposited there over 20 years ago, no doubt when local coal opencasting work ceased. I remember seeing similar machines during the 1960s.
Out of idle curiosity, I recently copied off the maker’s details from it and tried googling them, in the expectation of being able to find out a lot about it. However, no information seemed to be available.
It states:
ONIONS TRACTOR EQUIPMENT
MANUFACTURED BY
VICKERS-ARMSTRONG TRACTORS LTD.,
ONIONS WORKS,
BILSTON, STAFFS,
MODEL NO. 12-10
MARK NO. II
SERIAL NO. 1206.
Being of metal about 2 inches thick, and some 20 feet long, these machines are pretty well indestructible so I suppose plenty survive and perhaps are still in use. Is it a common model? It seems so strange that I could find nothing about the factory on the Internet. I am a lead mining historian (though from a coal mining family) and my knowledge on coal mining is limited.

You obviously haven't googled very hard:



http://www.contrafedpublishing.co.nz/Contractor/2009/July+2009/The+history+of+the+towed+scraper.html 

http://www.google.co.uk/search?q=onions+scraper&hl=en&prmd=imvnsfd&tbm=isch&tbo=u&source=univ&sa=X&ei=S3BEUMP0EueK0AWi8YGoAw&ved=0CEcQsAQ&biw=1152&bih=573 

Towed scrapers were in common use in the construction industry until the 1960s, and were still to be seen in limited numbers until quite recent times.

They still occasionally appear on pipeline contracts, because some contractors still use cable-equipped Caterpillar sidebooms, but otherwise they are pretty much out of use now.

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.....cable-equipped Caterpillar sidebooms....

We still have 2 of them, and they are as lethal now as they were back in the day 😮 I have at least 2 photos of them on their sides :lol: along with Volvo dump trucks that turned over if you just looked at them the wrong way :lol:

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I have at least 2 photos of them on their sides

Very interesting if they rolled 360 and you finished up with the ropes round the drawbar.

Either roll it back 360 or un-thread and re-thread all the ropes. Not easy either way!

You can see the attraction of hydraulics.

Thank you all for sorting it out. I had just googled the phrases given on the manufacturer's plate and this yielded no hits.