G&SWR 540 Class

Glasgow & South Western Railway 540 Class
Type and origin Power type Steam Designer Robert Whitelegg Builder North British Locomotive Company, Hyde Park Works, Glasgow Serial number 22886-22891 Build date 1922 Total produced 6
Specifications Configuration: ​  • Whyte 4-6-4T Gauge 4 ft 8 1⁄2 in (1,435 mm) Driver dia. 6 ft 0 in (1.83 m) Loco weight 99tons Boiler pressure 180psi Superheater Robinson Cylinders Two, outside Cylinder size 22 in × 26 in (559 mm × 660 mm) Valve gear Walschaerts
Performance figures Tractive effort 26,741 lbf (118.95 kN)
Career Operators G&SWR • LMS Class G&SWR: 540 Power class LMS: 5P Disposition all scrapped

Type and origin
Power type	Steam
Designer	Robert Whitelegg
Builder	North British Locomotive Company, Hyde Park Works, Glasgow
Serial number	22886-22891
Build date	1922
Total produced	6

Specifications
Configuration:	​
• Whyte	4-6-4T
Gauge	4 ft 8 1⁄2 in (1,435 mm)
Driver dia.	6 ft 0 in (1.83 m)
Loco weight	99tons
Boiler pressure	180psi
Superheater	Robinson
Cylinders	Two, outside
Cylinder size	22 in × 26 in (559 mm × 660 mm)
Valve gear	Walschaerts

Performance figures
Tractive effort	26,741 lbf (118.95 kN)

Career
Operators	G&SWR • LMS
Class	G&SWR: 540
Power class	LMS: 5P
Disposition	all scrapped

The Glasgow and South Western Railway 540 Class were 4-6-4T steam tank locomotives designed by Robert Whitelegg and built in 1922, shortly before the G&SWR was absorbed into the London Midland and Scottish Railway (LMS). They were referred to in official G&SWR publicity as the Baltic Class, although they were also known more prosaically to enginemen as the 'Big Pugs'.

The G&SWR had historically favoured small tender locomotives for almost all duties other than light shunting, and prior to the delivery of the Baltics its only passenger tank engines were 14 small 0-4-4Ts built for suburban services. However, Robert Whitelegg had previously served as Locomotive Superintendent of the London, Tilbury and Southend Railway which made almost exclusive use of tank engines on its heavy commuter traffic, and he brought this experience with him when he joined the G&SWR as Chief Mechanical Engineer in 1919. During his time at the LT&SR Whitelegg had designed the first 4-6-4T locomotives to operate in Great Britain; the LT&SR 2100 Class. Some of the G&SWR's passenger traffic resembled the LT&SR express services, so Whitelegg again opted for a 4-6-4T.

The new Baltics were built to a very high specification and were intended to represent the very best practice of their time, so they were very expensive to build. They were also easily the most powerful locomotives ever operated by the G&SWR, and the company made the most of their delivery for publicity purposes. In service the locomotives performed very well on express passenger trains between Glasgow St Enoch and the Ayrshire coast towns or Kilmarnock, however they were expensive to maintain.

Within a few months of delivery the locomotives passed into the ownership of the newly formed London, Midland and Scottish Railway, and their green G&SWR livery was replaced by LMS crimson lake. By the end of the 1920s they were being repainted into lined black.

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