British Rail class 56 and Electroputere LDE 3500

The class 56 originated in the need of British Railways for a new power class 5 diesel locomotive in the seventies. It was specified that the bodyshell and many mechanical parts would be from the class 47. The engine was a Ruston-Paxman 16RK3CT, that was a development of the English Electric diesels. It was rated at 3,520 hp, but set at 3,250 hp. Instead of the main DC generator of earlier diesel-electrics, now an AC alternator powered the DC traction motors via a rectifier.

Since the British builders didn't have capacities at the time due to years of cost savings, the manufacturing was transferred to Electroputere in Romania. They called the type LDE 3500 and delivered the first 30 in 1977 to Britain. It didn't take long until it was found out that they were of poor build quality and had to be withdrawn after only a few years. They only entered service again after extensive rebuilds. So a low-rate production of a revised design was started at BREL. Until 1984, they built 85 at Doncaster and 20 at Crewe with sub-assemblies coming from other works.

All in all, they delivered valuable services. Although maintenance wasn't as easy as for the modular class 58, they were less prone to wheelslip than this. In 1995, all remaining locomotives came to the English Welsh & Scottish (EWS). Withdrawals started soon, with the last ones being withdrawn in 2004. After some years of storage, many were sold to a multitude of new owners. So some were soon used in construction trains, some were used by private operators for freight traffic and three even came to Hungary.