GWR 633 Class

The GWR 633 Class were 0-6-0 tank locomotives designed by George Armstrong and built at the Wolverhampton railway works of the Great Western Railway between November 1871 and April 1872. These were always southern division locomotives but over the years some were fitted to work the metropolitan lines and played a large role in the transportation of goods from Acton to Smithfield. Unusually, they had side (not saddle) tanks, and inside frames, with wheels of 4 ft 6 1⁄2 in (1,384 mm) in diameter and a wheelbase of 15 ft 6 in (4.72 m). The weight was 34 tons 12 cwt. There were twelve locomotives, numbered 633-644.[1]

GWR 633 Class
Type and origin
Power typeSteam
DesignerGeorge Armstrong
BuilderGWR Wolverhampton Works
Specifications
Configuration:
​
 • Whyte0-6-0T
Gauge4 ft 8 1⁄2 in (1,435 mm) standard gauge
Driver dia.4 ft 6 1⁄2 in (1,384 mm)
Wheelbase15 ft 6 in (4.72 m)
Loco weight14 long tons 12 cwt (14.8 t; 16.4 short tons)
Cylinder size16 in × 24 in (406 mm × 610 mm) dia × stroke
Career
OperatorsGreat Western Railway
Class633

Modifications

Nos. 643 and 644 were fitted with condensing apparatus when built, for working on the Metropolitan Railway Widened Lines and this was added to some others in the 1890s. These were the first size-coupled engines to be accepted for the widened lines. From 1887 they were reboilered with Dean pattern boilers and the wheels were enlarged by one inch (25 mm) by means of thicker tyres. The class was reboilered again with Belpaire fireboxes (but not pannier tanks) between 1916 and 1925. 633, 634, and all the others fitted with condensers were sent to the London Division and were cabless to work through then metropolitan tunnels. The ones not fitted with condensers were fitted with a cab and allocated to South Wales.

Service

They were intended for the Southern Division of the GWR. The condenser-fitted engines worked in the London area, others at Neath in South Wales. Withdrawal took place in 1928-34.[2]

References
  1. Smith, Martin, Steam on the Underground, Ian Allan Publishing 1994, p.22, ISBN 0-7110-2282-8
  2. le Fleming 1958, pp. E33-E35.

Sources
  • le Fleming, H. M. (1958). The Locomotives of the Great Western Railway, part five: Six-coupled Tank Engines. Kenilworth: RCTS.CS1 maint: ref=harv (link)
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