The order for the construction of two diesel electric locomotives was signed between the English Electric Company (EE) and the London Midland and Scottish Railway (LMS) in April 1947.  The diesel and electrical components were designed and supplied by EE while the mechanical parts were designed and erected by the LMS at Derby Works under the guidance of Mr. H. G. Ivatt, the LMS Chief Mechanical Engineer. The locomotives were numbered 10000 and 10001 respectively.  The locomotives were given the class code  D16/1. No TOPS numbers were allocated as both units were withdrawn in advance of the implementation of TOPS. The first locomotive was delivered in December 1947 on the eve of nationalisation with the second unit being delivered to the nationalised railway British Railways (BR) in July 1948.  The main physical details of the locomotives are as follows:

Wheel arrangement                                        Co-Co

Length over buffers                                         61 ft 2 in (18.64 metres)

Overall width                                                   9 ft 3 in (2.82 metres)

Overall height from rail level                         12 ft 11.5 in (3.95 metres)

Total wheelbase                                              51 ft 2 in (15.60 metres)

Bogie wheelbase                                            15 ft 8 in (4.78 metres)

Wheel diameter                                              3 ft 6 in (1.07 metres)

Weight in working order                                127 tons 3 cwt (129.2 tonnes)

Maximum axle loading                                   21 tons 5 cwt ( (21.59 tonnes)

Number of traction motor                              6

Gear ratio                                                        55/18

Maximum tractive effort (starting)                 41400 lb (184.16 kN)

One hour tractive effort                                 18 500 lb @ 26 mph (82.29 kN @ 41.86 kph)

One hour rail power                                       1283 HP @ 26 mph (957 kW @ 41.86 kph) 

Transmission Efficiency                                   80.2%

Continuous tractive effort                              15000 lb @ 32 mph (66.72 kN @ 51.52 kph)

Continuous rail power                                    1280 HP @ 32 mph (955 kW @ 52 kph)

Transmission Efficiency                                    80.0%

Maximum service speed                                 93 mph (149.73 kph)


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The locomotives were tested using a dynometer car and a tractive effort curve was published in a brochure produced by EE in 1951.  The graph included tractive effort vs speed as well as tractive effort vs current in both full field and weak field conditions.  The graph was hand draw and was approximately 1/3rd of a standard A4 page in size. The graphs appear to be reasonably accurate although the slight increase in rail horsepower from 28 to 37 mph is interesting.  The transition from full field to weak field can be clearly seen at 38.1 mph as can the unloading point at 74 mph.  The article quoted speeds (using both locomotives) of 58 mph on the 1:106 of Grayrigg bank and 49 mph on the 1:75 of Shap with a train of 390 tonnes gross

The speed on Grayrigg definitely represents a full throttle effort however the indications are that  speed was still falling on the steeper 1:75 of Shap.  The article also quoted a run with both locomotives hauling 16 coaches of 545 tons gross which averaged 38 mph on the 1:75 of Shap and 36 mph on the slightly steeper Beattock bank. These also represent full power ascents which would be expected for publication in a company brochure

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