Bulleid's Diesel-mechanical Shunter   '11001'.

11001 running through Wallington Station in 1952.   Photograph reproduced by arrangement with Honeywood Museum, Carshalton, courtesy of Tony Price.

                                                          
Prior to nationalisation, the Southern Railway's experiments with diesels included Maunsell's three 350hp diesel electric shunters built at Ashford, which entered service in 1937.  Bulleid's batch of 26 new Class 12 diesel electric shunters which were also 350hp were already being outshopped, when this further design was tried.

Bulleid's prototype 11001 was also designed and built at Ashford, and used the same 4' 6" Bulleid-Firth Brown type wheels as the Class 12 shunter; however this shunter was installed with a larger 12 cylinder Paxman RPH series V-type diesel engine, with a maximum of 500hp output at 1250 rpm.

And to produce a shunter that could drag pick-up freights at greater speed, 11001 incorporated a mechanical gearbox set up to give a 45 mph top speed.

Drive was through a Vulcan Sinclair fluid coupling to a 'Synchro-Self-Shifting' gearbox which provided three forward and reverse gears in either high or low range.

The plate sided chassis was somewhat akin to a standard tank engine, but it is perhaps curious that the drive from the rear jack crank shaft was taken to the centre axle through chunky connecting rods, resulting in massive balance weights on the centre driving wheels and jackshaft cracks.

11001 as introduced in B.R. black livery.
Photo: British Railways.

A rear view of 11001 showing the very plain cab and domed roof.  Note the massive connecting rod from the jack shaft to centre crank pin.
Photo: courtesy of C.J.M. collection.

                                                          
Although innovative in it's own way, 11001 was not one of the more obviously Bulleid influenced designs conceived during his time as CME.  That said, its body styling was unique, with a long bonnet which unusually housed the fuel tank at the front, rather than a radiator; and a very high arc cab roof with large angled front windows.

Principle Dimensions:    Height, rail to top of bonnet: 10' 9".
Height, rail to top of cab vent: 12' 11½"    Overall length:   33' 3"
Wheel centres:   6' 3"    Weight in working order:     49 tons 9 cwt 3 quarters

                                                          
11001 it is apparently credited as the first diesel locomotive put into service by British Railways.

The locomotive was completed in 1950, after Bulleid had departed the his C.M.E. post, the same year as diesel 10201 was outshopped.

11001 was originally finished in plain black livery, unthinkable in these days of Health & Safety legislation, but was later repainted into green.

For most of it's life 11001 was based around Norwood yard.  It was intended for shunting and short pick-up trips, but the locomotive was just fitted with air brakes, with no provision for train braking.

The compromise meant it was was not entirely successful at either role, and was gone within 10 years.  Clive Young recalls that it suffered a gearbox failure, which would agree with the 1958 photo below, which shows 11001 in a forlorn state with the gearbox clearly removed.

A fascinating picture of 11001 c.1958 at Ashford Works, probably just prior to withdrawal in 1959.  Notice how the whole gearbox / jackshaft assembly has been dropped out just like an axle set.  Also clearly shows the double brake shoes per wheel.   Photo: Ron Fisher.

                                                          
As a variation on modelling the standard Class 12 shunter, this would make an useful yet compact model in 5 inch gauge; the casing should be big enough to fit a couple of reasonably sized batteries, enough for a few hours of shunting wagons.