About

No 790 is GWR chief mechanical engineer, George Jackson Churchward’s dynamometer car and was built in 1901 at Swindon at a cost of £890.

It was designed for measuring real world engine performance and was marshalled behind the locomotive while the technicians in the coach monitored speed, steam pressure, coal and water consumption, tractive effort and so on. Its internal equipment included a Hallade recorder, which recorded on a roll of paper, revolved by clockwork, the oscillations of the coach during a test journey, thus indicating the condition of the permanent way (i.e the track). There was also a retractable, flangeless wheel for recording speed, which could be raised and lowered on to the track as required.

No 790 has a ‘royal’ clerestory roof and has observation windows at each end and side lookouts.

Its last GWR run was in October 1947 when Castle class No 5056 Earl of Powis reached 96mph. Its last BR run was behind BR Standard 9F No 92178, which reached 87mph.

790, which by then had its final number W7W, was withdrawn in 1961 and stored at Swindon until purchased for preservation in 1965. Sadly, none of its fascinating recording equipment survives.

Specifications

  • Designer -|- William Dean
  • Builder -|- GWR - Swindon Works
  • Build Date -|- 1901
  • Cost -|- £890
  • Diagram -|- Q20
  • Total of Diagram Produced -|- 1
  • Lot -|- W293
  • Gauge -|- Standard Gauge - 4ft 8 12 in (1,435mm)
  • Bogies -|- Dean 8'6
  • Bogie Wheelbase -|- 8ft 6in (2.59m)
  • Wheelbase -|- 39ft 3in (11.96m)
  • Length -|- 45ft (13.72m)
  • Width -|- 9ft 34 in (2.76m)
  • Height -|-
  • Tare Weight -|- 27 long tons (27,433kg)
  • Passenger Capacity - 0

Current Status

  • Status -|- Awaiting Restoration
  • Location -|- Buckfastleigh
  • Livery -|- GWR Lined Chocolate and Cream
  • Owner -|- South Devon Railway Trust

Drawing

Pictures

If you have any images of any of our locomotives, at any time or any place and don’t mind letting us use them, then please get in touch with us.

No. 790 in the News

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Company

South Devon Railway Trust, Registered Office:
The Station, Dartbridge Road, Buckfastleigh, Devon, TQ11 0DZ
Registered in England No. 01150799
Registered Charity No. 800299

Contact Us

T: 01364 644 370
E: trains@southdevonrailway.co.uk

© Copyright South Devon Railway

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