wheel-slip detector). The main generator and the traction motors are identical to those used on the BR Type 3 and Deltic locomotives. Contrary to BR Class 50, the Portuguese Série 1800 locomotives were built to be as much compatible with the smaller Série 1400 (themselves similar to BR Class 20) as possible and also to use as many common components as possible. They were the only diesel locomotives in Portugal authorised to run at 140 km/h. The CP Série 1800s were all withdrawn in 2001 and (as of 2012) several have been cut up, and the future of the rest is unclear. Today some of these locomotives are still mostly seen as freight trains rather than passenger trains. Locomotive 1805 has been preserved in operational condition by the Portuguese National Railway Museum at Entroncamento. Since the 1980s it had been painted in CP's corporate orange livery; it has been repainted in its original distinctive blue livery by the CP workshop at Contumil near Porto. While still an integral part of the National Railway Museum, is set to return to service pulling tourist trains in the Douro River Line. Preservation Class 50 locomotives proved popular with rail enthusiasts, with eighteen locomotives saved for preservation and several subsequently registered for use on the mainline. An ambitious project involving preserved Class 50s was "Operation Collingwood", an engineering charity established in the early 1990s. The aim had been to train young engineering apprentices by getting them to rebuild railway locomotives and Class 50s were chosen both for the fact that they were a British design throughout and that all were named (so the apprentices would derive some pride from rededication ceremonies at the completion of their work). To this end, Operation Collingwood purchased and stored 50001, 50023, 50029, 50030, 50040 and 50045. All except 50029 and 50030 were heavily stripped examples sold to scrapyards for final cutting up. The intention was to restore them by using industrial sponsorship money to build an engineering centre and overhaul the components, making brand new ones where necessary to overcome lack of availability of some parts unique to the original design. These ambitions failed when sponsorship did not reach the required level and the project lost various key people. The charity was wound up in 2002; 50001/023/040 and 045 were sold back to scrapyards and their state as little more than bodyshells deterred most further preservation attempts. 50045