Frequently Asked Questions

Do you have a question about Deltics or the society?

Contact us on infoAT
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How do I get to the DPS Depot?

The DPS Depot is located at Barrow Hill, which is near Chesterfield w from where a regular bus service operates. For those travelling by road, the depot is close to the M1 (Junction 29/30). The depot is open most weekends. For further details of how to get there with maps and details of bus services, please visit the ‘Where we are’ section on Barrow Hill Roundhouse Railway Centre website by clicking here.

How do I submit photos for the website?

Photos (recent or ‘nostalgic’) and information for the website is always welcome, please contact the DPS webmaster at webmasterAT
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How do I access the forums on this website?

The forums are not currently active, although a user account enables you to see extra sections on the website – for example, polls and news stories not available to non members. DPS members can obtain a user account by e-mailing the membership secretary at membershipAT
(amending ‘AT’ to read ‘@’)quoting your name, address, membership number and e-mail address.

When were the Deltics withdrawn from service?

The first two Deltics to be withdrawn were 55001 ‘St Paddy’ and 55020 ‘Nimbus’ on January 5th 1980, although neither of these locos had worked since March 1978. Both were cut up by the end of the month. The next casualty was 55003 ‘Meld’ which was withdrawn on 30th December 1980 at York followed by 55005 and 55006 in February 1981 at York. 55012 ‘Crepello’ was next being withdrawn at FP on May 18th followed by 55018 ‘Ballymoss at York on October 18th.

The final run down of the class started in earnest in November 1981 when 55004 and 55011 were withdrawn at Stratford, and 55014 at York. By the end of December all remaining Deltics were withdrawn with the exception of the four ‘railtour’ locos. These were 55002/9/15/22 which survived until January 2nd 1982 for the farewell railtour.

Does a Deltic sound different to any other diesel loco?

A Deltic sounds very different to any other locomotive. At idle, the phasing gears inside the engine can be heard as can the scavenger blower and the exhaust. The noise varies depending on where and how far you are standing in relation to the locomotive. The engine note is like a low, rumble of thunder.

An 18 cylinder Napier Deltic rail traction engine idles at 700 rpm (faster than most other diesels at full bore) and can run up to 1500 rpm. As the engine rev’s increase the Deltic engine also changes character. The rattling and vibration in the phasing gear changes frequency, and the engine note becomes a higher-pitched, very smooth drone. For this reason the locomotives are sometimes nick-named ‘Drones’ or ‘Lancaster Bombers’.

After hearing a Deltic engine, be it in a Class 55 or a naval craft, it is very difficult to mistake them for anything else.

Does a Deltic Look Different?

When studied a Deltic has a beautiful symmetry to its design. Having two engines the exterior number 1 and 2 ends are hard to differentiate (1 end has an access plate to the exhausters while 2 end has a waste pipe from the urinal). Unlike many other classic English Electric designs the cab had two tear shaped front windows contributing to the impression of power that the class exude.

Quite apart from the external design of the Class 55 locomotive, a Deltic exhaust is similarly unique. When setting off the Deltic engines can expel two large plumes of exhaust. The two stroke engine design carries over a quantity of oil into the exhaust collector drum. This gets hot, leading to a pale blue exhaust trail in many cases. After standing idling for some time, a Deltic can produce a cloud of smoke that many steam locomotives would find hard to match. Notwithstanding an engine that is running efficiently will soon loose this trait and the exhaust will clear.

Was a Deltic Engine Operated Differently?

The locomotives were operated very differently to any other machines in the British Rail fleet. They were the first locomotives expressly designed to be maintained by component replacement. Up until that time, a locomotive had an associated engine and generator. If it broke, it went into the local repair shop and was fixed. The locomotive then returned to service days or weeks later. The Deltic was designed to be diagrammed for a high availability. Thus, 44 engines were ordered for the locomotives themselves, along with 13 further spare engines. When a power unit developed a problem, the locomotive would enter Doncaster Plant, the power unit was exchanged, locomotive tested and released. Often an engine change could be accomplished in only a day. This method of repair-by-replacement enabled the Deltic locomotives to achieve higher mileages than other locomotive classes. Indeed, in less than 12 years D9010 /55010 became the first Deltic to achieve 2 million miles.

Was the Deltic Engine Unreliable?

Fundamentally no. The Deltic engine was a complicated machine. Class 55 Deltic engines were initially repaired and tested by Napier in Liverpool and then BR in Doncaster. Throughout their lives various problems did occur, but were eventually solved. In terms of miles per casualty, the Deltic engine was broadly similar to slow diesels, but suffered higher stress levels due to the nature of its work and the fact that it operated at much tighter tolerances than more conventional units.

In the mid 70’s the locomotives suffered because of the unavailability of spares. Also at the end of their lives, when repair costs were being further trimmed, it was not unusual to see locomotives travelling on one engine. The Deltic locomotives were withdrawn in 1982 (at 20 years of age) as BR considered that there were no services that needed their high power. The Deltics also suffered the fate of many small first generation diesel classes; there were relatively few locomotives and thus considered a non-standard class. Furthermore, the fact that few crew outside the confines of the East Coast Main Line had experience of Deltics meant that cascading them to other regions was undesirable. The 20 year Deltic rule saw them replace steam and pave the way for high speed trains (HST’s), and subsequent electrification.

What makes a Deltic Engine so different?

Most internal combustion diesel engines used in marine or rail-traction use are of a conventional ‘straight’ or ‘Vee’ configuration, running a four-stroke combustion cycle. Often they will be slow revving (operating at perhaps 800rpm maximum), but with high torque characteristics. In the 1950′s, when the British Rail modernisation plan diesels were being developed, conventional engine designs tended to be heavy, and have a poor power to weight ratio (e.g. the Class 40’s and 45’s). Engine assemblies such as turbo chargers and cylinder heads were over-engineered to cope with the stresses associated with high-mass engines. Typically, many diesels operated at a power to weight ratio of around 20hp per ton. The Deltic engine was developed by the D. Napier & Sons at Acton and constructed at their works in Liverpool as a compact unit with a very high power to weight ratio.

The Admiralty saw the engine’s potential for use in fast patrol craft however it was the Chairman of English Electric later Lord Nelson of Stafford who saw their potential in a rail traction unit. A Deltic is named after the engine configuration, an inverted triangle – similar to an inverted Greek letter Delta.

The engine consists of three cylinders arranged as an equilateral triangle. A class 55 Deltic engine has six banks, i.e. 18 cylinders with three crankshafts. Opposed pistons were fitted in each cylinder (removing the need for heavy cylinder heads seen on conventional engines) and these attached to the three crankshafts (one at each point in the triangle). These crankshafts feed into a phasing gear case from which an output shaft drives the main generator. Other outputs and drives operate the auxiliary generator, scavenger blower, pumps, etc. Being a two stroke eliminated the need for valves and having a scavenger blower ensured that the engine efficiently expelled the exhaust and recharged the cylinders with clean air.

At 1650 bhp a rail traction Deltic engine is considerably de-rated (the turbo-charged version was capable of 3,700 bhp. The engines optimally run at a constant high speed but railway timetabling and signalling means frequent stops and slacks. By derating the engines a longer engine life can be obtained. Regardless the Class 55 locomotive at around 100 tons and with 3300 bhp at call still remains one of the most successful low weight high speed locomotives ever.

How many other Production Deltics were saved?

In addition to the three locos owned by the DPS, another three Deltics escaped the cutter’s torch in 1982. 55002 ‘The Kings Own Yorkshire Light Infantry’ became part of the National Collection and was exhibited at the National Railway Museum, York. since then it has been partially overhauled by Brush (Loughborough) and after a sojourn at Wabtec (Doncaster) awaiting completion of repairs it is was moved in June 2004 to the DPS Depot. Following cosmetic restoration in BR blue, it has since returned to the NRM at York and has since been returned to main line working order by the ‘Koyli Group;.

55016 ‘Gordon Highlander’ and 55022 ‘Royal Scots Grey’ were purchased from BR by the Deltic 9000 Fund, which later became Deltic 9000 Locomotives Ltd. In 2004 55016 was sold to a private owner and moved to Tyseley while 55022 was purchased by Beaver Sports and has been fully restored for use on Network Rail lines. It is now based at the East Lancs Railway, while 55016 (now painted green as D9016) was acquired at a later date and moved to Bury in January 2010.

In addition to the locomotives the DPS own the Number 2 end cab from 55008 mounted on a low loader. The cab was recently restored by DPS volunteers and converted into a train simulator for the NRM’s Railfest 2004 event and is a popular exhibit at Barrow Hill. Also saved is the Number 1 end of 55021 which is now in the hands of the South Wales Loco Cab Preservation Group in Bridgend.

What happened to the remaining Deltics?

The remaining 16 Deltics were cut up by BR at Doncaster between 1980 and 1983. The DPS obtained a large number of spares, including five power units, which are now located at the society’s depot at Barrow Hill. Various other parts, such as bogies, were re-used by BR.

How many colour schemes have the Deltics carried?

In BR service, the Deltics carried two basic colour schemes – first two-tone green, followed by BR blue. There were several variations on these liveries including no/small/full yellow warning panels on the green, and white window surrounds on blue. In more recent years (between 1999 and 2003), 9016 ‘Gordon Highlander’ carried the purple/grey colours of Porterbrook Leasing. This livery is now itself historic, following a repaint into two-tone green.

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