LMS Route: Evesham to Birmingham

Kings Norton Locomotives: mrkn2005

A down train of Esso Class B 4-wheel tank wagons passes Kings Norton goods yard as ex-MR 0-4-0 No 41535 and an unidentified ex-LMS 4-6-0 Black 5 locomotive approach the camera. Alan Drewett Writes, 'In comparison with some of the other Esso designs this wagon has a simple yet elegant twin-saddle attachment between cylinder and chassis although the 22ft 6in cylinder noticeably stops short of the full length of the chassis (27ft 9¾in over buffers) and is far enough inside the loading gauge to permit sub-solebar length ladders to be attached amidships. Other visible refinements include roller bearing axle boxes and two brake blocks acting on each wheel. The latter were applied either by manual lever during shunting or by twin vacuum cylinders as part of a vacuum brake fitted train. Like later airbraked monocoque tank wagons, the buffers were either hydraulic or pneumatic. The two stars are also a clue that this 15' wheelbase Class B wagon was designed with the post-1955 Modernised British Railways in mind and intended to be run at over 45 mph without frequent inspection stops during transit. Such special treatment was made necessary by the general age and obsolescent design of Britain's tank wagon fleets, which had not been Nationalised along with the rest of British Railway in 1948.

In 1956 the Esso Petroleum Company Limited approached British Railways to design a maximum capacity four wheeled tank wagon within the existing 35 ton gross laden weight limit and more than 800 examples of this pattern were constructed by various builders to carry both Class A and B liquids. Load discharges were to be controlled by an internal rod and plug operated by a handwheel on top of the tank barrel, some 12ft 6in above rail level. The same wagon design was also built for operators such as TSL in the early 1950s by Powell Duffryn of Cardiff, later to absorb the remains of the Gloucester Railway Carriage and Wagon Company. In the case of Esso's Class B variants the loads would have included diesel fuel and kerosenes with steam coils fitted to assist the offloading of heavy fuel oils. An alternative way of heating tar (also known as bitumen ashphalt) from its room temperature solid state to fluid aboard post Second World War wagons was by means of flame tubes. These would be set low on the wagon ends and end in a chimney at the top, the heat being provided at the discharge location by means of a gas lance. Indeed, one of my earliest memories of visiting the East Somerset Railway at Cranmore was walking toward the steam locomotives saved by David Shepherd past lines of what looked like petrol tankers that had been set on fire! Luckily the "SUKO" (short for Shell UK Oil) wagons did not explode but just wafted warm tar as they prepared for bottom discharge of their loads - possibly sourced from Californian crude oil or the tar sands of Trinidad. Unlike Class A tank wagons, Class B vehicles were permitted to be coupled next to guards vans and locomotives without any intervening barrier vehicle.'

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