Caledonian 2-6-0 Locomotives in Great_Britain

Class 34/3F (Locobase 20141)

Data from "Caledonian Railway", Locomotive Magazine, Volume 19 (15 August 1913), p. 181. See also Steamindex's disimissive description of the design at [], last accessed 9 January 2017 and Alex K Bowman, "The McIntosh Locomotives of the Caledonian Railway", Railway Magazine, Volume XXXIV, January-June 1914 , pp. 201-210.

It's not often mentioned that superheating an existing design added considerable weight. In the case of this quintet, fitting the 812 0-6-0 design described in Locobase 5538 with a superheater added 2 1/2 tons (5,600 lb or 2,540 kg). "The extra weight," noted the LM report," is largely in the neighbourhood of the smokebox and cylinders." So the Caley tacked on a truck to carry the weight and turned the six-coupled into Moguls; as such, they were often described as the "Converted 30 class" because some 652s had been superheated in 1912.

John McIntosh took the opportunity to increase cylinder diameters by an inch and feed them steam through 8" (203 mm) piston valves. Steamindex observed that the truck had lateral springing, but, although resembling a radial truck, didn't have the curved guides normally associated with them. Yet the LM report said that the leading truck's inclusion also stemmed from "the inducement of greater safety at high speeds in the provision of a leading truck" adding that in service "these engines have been noted for smooth and easy running."