The Class 50 Story

Picture

From DP2 Prototype to British Railways Premiere Mainline Diesel Locomotive

A brief history of the fifty 50’s from the design stage in 1956 to the withdrawal of the final member of the class in 1994

The Class 50 Concept

The birth of the Class 50 was largely due to the realisation in 1966 that B.R. required a “stop gap”, high power, high speed class of locomotive for use on Anglo-Scottish West Coast Main Line Services in pre-electrification days. It was decided that the Class should be based on the well proven English Electric DP2 prototype, but with considerably modified bodywork and incorporating electric train heating, full air braking and slow speed control. All class members were also fitted for multiple working, but, initially, only the first member of the class D400 had these cables fitted.

The DP2 Story                                              

“Diesel Prototype 2” entered service on the London Midland region in May 1962. It bore the Vulcan Foundry No D733 and English Electric Rotation No 3205 of 1961. 

 Unlike its competitors, it was denied the luxury of a name, several including “Challenger” had been suggested but rejected by the management, so that it always bore its simple project code DP2, DP1 having been regarded as the prototype “Deltic” of 1955. In concept it was a simple, lightweight and robust unit in the true English Electric tradition and the main power producing and transmission components were common to those of a class 50. In working order DP2 weighed only 107 tons with a maximum axle load of 17.5 tons giving it a significant advantage over its competitors. For a diesel-electric employing a single heavy medium speed engine it at last provided comparable power to weight ratio (871b/hp), comparable to the diesel hydraulics of the Western Region.

Some leading particulars of DP2 were:  

Locomotive weight, empty:                                                                       97.2 tons

Length over buffers:                                                                                  69ft 6in

Overall width:                                                                                           8ft 9.5 in

Overall Height:        

            12ft 10 in

Total wheelbase:                                                                                      58ft 6in

Bogie wheelbase:                                                                                     13ft 6in

Bogie centres:                                                                                          45ft

Wheel diameter:                                                                                      3ft 7in

Minimum curve negotiable:                                                                       4 chains (260ft)

Maximum tractive effort:                                                                           55,000lb

Continuous tractive effort:                                                                         36,000lb at 21.5 mph

Maximum service speed:                                                                           90 mph (105 mph provided for)

DP2 Operational Experience

On the LMR, DP2 had been working 2,000bhp Type 4 schedules and was therefore, not fully extended. This brought about the agreement to transfer the unit to the Eastern Region in July 1963. Here an opportunity for more rigorous proof of its reliability had arisen. Withdrawal of the 3,300bhp “Deltics”, one by one for train heating boiler modifications had been ordered and this operating loss was covered by rostering DP2 to a “Deltic” diagram, no mean feat for a 2,700bhp locomotive. Over 58 consecutive days it covered 43,000 trouble free miles, a record probably never regularly equalled by any European locomotive operating Inter-City services over comparable distances. During its first 21 months and 270,000 miles DP2 suffered only one on line failure, this was caused by water freezing in the outer radiator coils during a protracted period of slow running and signal stops in freezing blizzard conditions in January 1963.

 A history of a locomotive must record its demise, for DP2s brilliant career was abruptly terminated on the 31 st July 1967 in tragic circumstances. DP2 was hauling the 12.00 Kings Cross-Edinburgh service, part of its then regular diagram. Whilst crossing the Vale of York at 80mph, Driver John Evans and Secondman Dennis Smith saw clouds of dust billow across the track some 600yds ahead. They made a full emergency brake application. Out of the dust suddenly lurched a derailed wagon and collision was inevitable. On impact speed had been reduced to just below 50mph. Both DP2 and the leading seven coaches were derailed but remained upright, sadly 7 passengers were killed and 45 injured, though the enginemen survived. The nose and left hand side of DP2 had been ripped away as was the left side of the leading coach.  

DP2 was removed to York depot and on 8 th September was towed to Vulcan Works; the sad procession arrived behind English Electric Type 3 No D6947. At Vulcan Works DP2 was deemed to be beyond economic repair and dismantled during 1968, undamaged internal equipment was removed for later re-use. Such was the sad end for one of the most successful Main-Line prototypes to be built in the world. Its final mileage was 627,000 miles.

Construction and early success's

Following the success of DP2, British Rail placed an order for 50, Class 50 locomotives, Then known as the D400 series. Construction of the class began at English Electric's Vulcan works during early 1967 with the first loco (D400 now 50050) entering service from Crewe in the October of that year, deliveries then proceeded at a rapid rate with the final member of the class entering service during November 1968.  

All locos were initially leased by “English Electric Leasing Ltd”; this fact being indicated by a small die cast plaque carried mid bodyside by all locos at the time. 

The initial agreement guaranteed an 84% availability level, Crewe depot was the prime operating base although at various times the locos were loaned to other depots for crew training or test purposes.  In an effort to maintain the high availability requirements spare engines were located at Crewe, Carlisle and Polmadie depots.  

During 1969, multiple working cables were fitted to the remaining class members as a prelude to the use of pairs of locos on the greatly accelerated Anglo-Scottish services, which became the norm from 5 th May 1970. 100 miles per hour running became commonplace, with cuts of up to 45 minutes from the pre 1970 journey times.

The Western Region Saga 

As a result of the success of the class on the West Coast Main Line it was decided that members of the class were to be transferred to the Western Region. On the 11 th October 1972 class member D400 was transferred to Bristol Bath Road to commence crew training, it was joined shortly by sister loco D401 and by mid summer 1973 both locos were operating in revenue earning service on the Paddington-Bristol expresses.  

A further 3 class members were transferred to the W.R. during 1974, with a mass transfer taking place to the region upon inauguration of the “Electric Scots” WCML service in May 1974, final transfer of the remaining 50's taking place in May 1976.  

British Rail finally purchased the locos from English Electric during the mid “70's”, the small bodyside plates being removed at this time.

Refurbishment

The class suffered poor availability shortly after its arrival on the Western Region, partly due to lack of staff familiarity with the locos and partly due to the extremely sophisticated control system that had been fitted.  

Hard work on the part of the depots led to an improvement in availability, but during 1977 the decision was made to embark on an extensive refurbishment program to be carried out at British Rail's Doncaster Depot.

This was to include the removal of the inertia filtration system, the rheostatic braking and the slow speed control fittings plus a complete rewiring and the fitting of the now familiar headlight.

 50006 entered Doncaster in September 1977 for refurbishment, finally returning to service in September 1979, the first of the reborn locos.

Refurbishment then followed for all other class members, the final loco to be refurbished being 50014 which was completed during late 1983.

The first six locos to be refurbished appeared from the works in their original livery, but, on the 15 th August 1980 50023 reappeared resplendent in the new eye catching livery, since adopted for the Class. 50030 was the last to be repainted appearing in September 1984, however 50007 had reverted back to the old style of livery but in “Brunswick Green” for its imminent renaming.  

Locomotive Naming 

From an enthusiasts point of view possibly the most gratifying decision was to name class members, 50035 being the first member of the class to be named on 17 th January 1978 at Plymouth and the last class member 50006 in September 1979.

On 25 th February 1995 on the 50 th anniversary of the composer Sir Edward Elgar's death it was decided by the management of the Western Region to rename class member 50007, then named Hercules, after the composer. This did not go down well with the enthusiasts who presented a petition to the management but to no avail, the locomotive was renamed Sir Edward Elgar at a ceremony at Paddington Station.

However it would seem that the locomotive itself was not happy with its renaming and had the last laugh by running late on its post naming run from Paddington to Oxford due to a failed traction motor.

The Twilight of the 50's 

In much the same way as the 50's replaced the 52's on the prime Western Region services, they themselves, were replaced by the HST's on the prime routes.  

 From May 1980 the class took over the haulage of the Waterloo-Exeter services over the former LSWR main line. Class members were also put on to a variety of duties including the majority of the ex GW main line routes from Swansea to Birmingham, Paddington to Penzance.  

The class were also in their latter years put to work on more mundane duties such as freight and postal diagrams and they also provided almost exclusively the power for the engineers trains in the Plymouth division.  

Finally, in February 1987 the first member of the class to be withdrawn from service was 50011 Centurion and from then on members of the class were slowly taken out of service as they failed or became too expensive to repair.  

The final pair of the class 50007 Sir Edward Elgar and 50050 (the first fifty) Fearless were withdrawn from service in March 1994 having completed the final Class 50 Farewell Railtour the “Terminator”.  Which ran from London Waterloo to Exeter and then back to London Paddington.

Chronology of the D400 Series.

May 1962 DP2 enters service

July 1963 DP2 moves to ECML on Deltic diagrams

July 1967 DP2 written off in tragic accident on ECML

August 1967 Order for 50 D400's Placed

  Final cost per locomotive £126,870.00

September 1967 D400s first test run to Chester

  D400s begin service on WCML

November 1967 Final member of the class, D449 enters service

October 1972 First member of the class on the WR

September 1977 Refurbishment program begins on the class

September 1984 Refurbishment program completed

January 1978 First member of the class 50035 named

September 1979 Last member of the class 50014 named

February 1980 50007 renamed “Sir Edward Elgar” at Paddington

May 1980 First of the class transferred to the SR

February 1987 First member of the class 50011 scrapped

March 1994 Final members of the class 50007 & 50050 withdrawn

CLASS 50 LEADING PARTICULARS

BR locomotives D400-D449

( English Electric Co Ltd ) as delivered

Axle Layout:                             Co-Co   

Weights

Total service weight:           117 Tons

Empty weight:                         112.5 Tons

Unsprung weight:                    21 Tons

Maximum axle load:               19.5 Tons

Principal dimensions

Length over buffers:               68ft 6in

Length over body:                   66ft

Overall width:                          9ft 1 1/4 in

Width over panelling:              8ft 10 3/8 in

Overall height:                         12ft 9 1/2 in

Total wheelbase:                    56ft 2in

Bogie pivot centres:               42ft 8in

Bogie wheelbase:                   13ft 6in

Driving wheel diameter:         3ft 7in (New)

Min wheel diameter:  3ft 4in

Clearance above rail level:    7 1/2 in

Power equipment

Diesel engine:                 English Electric 16CVST

Continuous rated output: 2,700bhp at 850rpm

Maximum tractive effort: 48,500llb at 18% adhesion

Continuous tractive effort: 33,000lb at 23.5mph

Rail HP continuous rating: 2,070

Full engine output:        Available between 15 & 87mph 

Braking

Brake force:                           84.9% of loco weight

Brake force:                           59 tons as displayed on loco 

Speed

Maximum permitted speed:   100mph

Copyright Alistair Field 2021