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Battery Multiple Unit - Derby 2-car BMU


The northern part of Scotland had an abundance of hydro-electric schemes. This 'white power' as it was known had a huge advantage over coal and oil which involved transportation to remote areas. As a result there were recurring proposals for battery electric railcars, which also alleviated the necessity for capital outlay on overhead equipment.

As early as 1954 the North of Scotland Hydro-Electric Board (NSHEB) had been having been prompting the BTC about using the power for traction purposes, although at this stage only battery locomotives were mentioned.

The 1955 report of the Electricity Consultative Council for the North of Scotland (ECCNS) suggested that experiments should be made with battery railcars on one or more of the branch lines where closure was imminent. This was brought up in the House of Commons, and the Transport Minister replied that the proposal was considered carefully by the BTC in consultation with the NSHEB and a great deal of detailed investigation undertaken. The Scottish Area Board of the BTC had concluded that the potential running and maintenance costs of battery railcars would make little difference to the economics of branch lines and further experiments would not be justified.

Obviously unhappy with this reply, Sir Robert Boothby raised the matter again in an adjournment debate, and also criticised the BTC's lack of support for railcars in general. Elaborating on battery vehicles, the Joint Parliamentary Secretary to the Ministry of Transport pointed out that battery vehicles were expensive in first cost, having to be built of a special light alloy because of the great weight of the batteries. The Commission would undertake experiments if the batteries could be recharged at 0.75d per unit, but the figure quoted by the NSHEB had been 2.1d a unit.

The public responded to this, stating that normal household "off-peak" rates were much cheaper than this, between 7pm and 7am, an ideal time for charging traction batteries. They pointed out that although the NSHEB did not offer an off-peak rate, it did charge less than 1d per unit for certain uses, and the public urged the matter to be re-addressed.

At the start of 1956 the Chairman of the ECCNS stated that the BTC had given a definite promise to carry out an experiment with battery railcars on a branch line in Scotland. The Council considered that their use should lead to increased passenger traffic on lines threatened with closure in it's area.

Formal Announcement

At a press conference in Glasgow on the 15th October 1957, Sir Ian Bolton, chairman of the Scottish Area Board of the British Transport Commission, announced that a battery multiple unit was being constructed at the British Railways Carriage & Wagon workshops at Cowlairs, with the intention of it being introduced the following summer on the Aberdeen - Ballater route. Accompanying Sir Ian Bolton were other members of the Scottish Area Board, the Rt Hon Thomas Johnston, Chairman of the NSHEB, and James Ness, General Manager of the ScR. The 117 seat unit would be introduced into a revised timetable in conjunction with steam power on the Deeside Line, which had a fair level of passenger traffic capable of being increased. The four daily steam returns would be increased to six; three of them by the battery railcar. It was hoped that the attraction of extra passenger traffic to the route, along with the performance, could be checked as a blueprint for the future of other branch lines.

Press conference

The image shows Mr Thomas Johnstone, Chairman of the NSHEB addressing the press conference in Glasgow. To his left is Mr James Ness, General Manager, and beside him is Sir Ian Bolton, Chairman of the Scottish Area Board who presided at the conference.

The North of Scotland Hydro-Electric Board, who had initiated the proposals some years before, acted as joint sponsor of the set with the Scottish Area Board of the British Transport Commission and management of the Scottish Region of British Railways. Its contribution was the electric traction and control equipment, and made an agreement to supply the charging current at no more than 0.75d. a unit for a period of two years. British Railways provided the mechanical portions, which were those from two in the series of diesel railcars produced at Derby Works in 1956 and modified slightly to take the more than 17 tons of batteries required. The batteries were supplied by Chloride Batteries Limited, under favourable terms, and the stationary charging plants at Aberdeen and Ballater were similarly supplied by Bruce Peebles Limited.

The origins of the two body shells remain a bit of a mystery. It is fairly certain though that two cars were taken from the "assembly line" of diesel mechanical Derby Lightweights being built at the time. Looking at the numbering of the lightweights, two numbers were not used in the middle of their numbering scheme. 79169-81 were DMBSs of lot number 30321 which formed power trailer sets with 79670-82 (30322). 79184-8 were DMBSs of lot no. 30324 and formed power twins with 79189-93 (30325). 79182/3 were unused. They could have been the original two numbers allocated for the battery set, and later changed to keep them separate, or it may be that the two cars were selected just before being released from Derby and so they may have reached the stage of having engines and transmission fitted, although this would be unlikely as it would be easier to take a part finished vehicle. The set was certainly at St Rollox Works in May '57, without traction equipment of any sort. They were numbered 79998/9 at this time, with the paint date of 21/9/56. Both bore notices that anyone climbing in them would be severely dealt with!

BMU before conversion

This image shows the two cars before the experimental equipment was added. As well as the bare underframes, of note is the grille under the centre cab window, normal on a Derby Lightweight but this was removed during the conversion. The date and location are unknown. Any information would be appreciated.

Non-Passenger Use

Details about the unit in preservation can be found here.

The following publications were consulted in the preparation of this article:
Railway Gazette; 25 Years of Research - C. Marsden; British Railways Scottish Region Staff Magazine; Scottish Urban & Rural Branch Lines - G. O’Hara; The Deeside line - Dick Jackson; Railway Observer; Railway Bylines Summer Special No.1.
All pictures are official ScR shots unless otherwise stated.

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