Masterclass – Class 28

Richard Foster examines a locomotive that had the power but, ultimately, enjoyed little of the glory.

A detailed look at this diesel underdog, plus how to improve Heljan’s rendition.

The last survivors were gathered in – or more correctly banished to – the north-west. They eked out their last days around Carnforth during the summer of 1968 and had all gone by the end of the year. Sorry… we’re not talking about ‘Black Fives’. Fifty years ago, BR disposed of what was arguably the most ambitious of all the ‘Pilot Scheme’ diesels. But the Metropolitan-vickers Type 2 ‘Co-bo’ was as flawed as it was ambitious. It’s often referred to by its TOPS classification – Class 28 – even though they’d all been withdrawn from active service five years before BR’S new computer planning and operating system was introduced. They might have all been withdrawn, but one was still lurking about on the national network to act as a reminder for what might have been. The design was almost perfect in theory. Let’s compare it to Brush’s Type 2, which would later become Class 31. The Crossley V8 diesel engine was a two-stroke and developed 50,000lb of tractive effort. The Mirrlees JVS12T V12 engine of the Brush design could only produce 42,800lb. Brush’s machine weighed 104 tons and that weight was carried on two six-axle bogies, but the middle axle was not powered. Metrovick’s new design would weigh just 97 tons and that weight would be borne on five axles, all powered.

ATTRACTIVE PROPOSITION

Really, what could be better than a powerful diesel engine (with fewer moving parts) that could develop a higher tractive effort than others in the same power band? It was the bogie arrangement that grabbed the attention. Both had heavy Commonwealth castings, but it was the pairing of a two-axle (‘Bo’) and three-axle (‘Co’) bogies that made the ‘28s’ unique. Quite why this arrangement was chosen has been lost in the mists of time. Contemporary literature focused mainly on the promise of efficient power that Crossley’s two-stroke diesel would bring. It has been suggested that the ‘28’ concept began life as a ‘Bo-bo’, but the addition of a three-axle bogie helped spread the weight. Whatever the reason, BR gave Metropolitan-vickers and Crossley its blessing, presumably in order to be able to test two and four-stroke diesel engines against each other. Twenty were ordered, as part of a ‘Pilot Scheme’ to build 174 diesels, from the likes of English Electric, North British, British Thomson-houston, Brush, and its own works at Derby and Swindon. The 20 ‘Co-bos’ were built at Metropolitan Vicker’s Bowesfield factory. Crossley supplied the engines with electrical gear coming from General Electric Company and Brush. The first, D5700, was accepted into traffic in July 1958 and went to Derby shed. D5700 was a handsome ”Its enough looking machine. 56ft 7in long body featured one large grille and several louvred panels, with slab-nosed cabs at each end. The three-screen arrangement was reminiscent of English Electric’s Type 4 but the outer windows wrapped around to the cabside. Things began to go wrong almost immediately. The class was officially allocated to Derby shed and locomotives were rotated, six at a time, to Cricklewood to work BR’S premier freight service. ‘Condor’ was an overnight London-glasgow container service. It emerged in the wake of the Suez Crisis of 1956, when rising fuel costs pushed freight back onto the railway, and it would often be loaded to 550 tons. Two ‘Co-bos’ were diagrammed to work ‘Condor’ north, do some work from Glasgow (heading as far as Stirling and Perth) and work a sleeper south again. However, such mileage put a strain on the Crossley engines and local duties were soon replaced by spending more time in depots to keep them in tip-top condition for ‘Condor’. Derby’s allocation was kept busy on the Midland Main Line from St Pancras to Manchester via Matlock. Again, weaknesses in the Crossley engines were revealed and less taxing duties soon beckoned. D5719, the last of the 20 locomotives, entered service in October 1959; by January/ February 1961, the whole class was in store. Engine failures had been traced to the crankcase, while excessive vibrations caused the curved screens to fall out. Who should pay for the repairs? Once BR and Metropolitan-vickers had worked things out, all 20 locomotives moved to Metropolitan-vickers’ Manchester factory for new crankcases and modified, flat-fronted windscreens. Despite Metrovick and Crossley’s desperation to prove that their design was a good ’un, BR declined to order any more. The class re-entered service from Barrow (11A), apparently banished to

“Metrovick The Type 2 ‘Co-bo’ was as flawed as it was ambitious