This wagon is a later, heavier, riveted version of SR 61107, the Bulleid cast steel well wagon. B900036 is one of
a batch of trolley wagons for transporting large heavy loads, such as transformers and steel castings, into continental Europe via the
Dover–Dunkirk train ferry. As a consequence it was built with a Westinghouse air through brake pipe in order to travel in European goods
trains, which were air-braked. It was built in June 1958 to diagram 2/525 at BR's Lancing Works in West Sussex, under Lot No.2927. As it was
built for the Southern Region, it was coded "Flatrol SB".
With the decline in the British heavy engineering industry, and the improvement in road heavy-haulage, the vehicle became surplus to traffic
requirements and was placed into departmental service with the Chief Civil Engineer (SR) in 1978, becoming DB900036. It was subsequently
modified with a steel floor, track stops and hitching points to carry tracked excavators. Its new TOPS diagram number was ZV189B and it was
coded "ZVR" (two-axle departmental wagon, "V" type, dual air and vacuum pipes).
B900036 was designed and built with volute spring suspension. Coil springs were substituted for the volutes later in its life, and the
resultant lively riding led to a 25 mph speed restriction on this and similar wagons. There was no place for such wagons on the modern
(post-privatisation) railway and it was acquired by Bluebell for use as a trolley wagon for smaller locomotive boilers and other uses.