In October 2002, 50029 Renown and 50030 Repulse were delivered to Peak Rail. Renown Repulse Restoration Group (RRRG) immediately set to work and began devising a plan of action. But sometimes the best-laid plans of mice and men …
RRRG begins work – ‘the eyesores’
It quickly became apparent to us that our new charges were hardly a fine advert for the professional image our hosts at Peak Rail sought to portray. Quite apart from faded paintwork and bodywork corrosion last attended to in the late 1980s, at the last Network SouthEast repaint, 50029 and 50030 were missing windscreens and the bodyshells were not weatherproof.
Operation Collingwood (a charity set up to train apprentice engineers on Class 50s) had at least had the foresight to block up the four exhaust ports on the roof of each locomotive – this prevents rainwater collecting in the turbochargers and ultimately overflowing into the engine cylinders. We agreed with Peak Rail’s management that our priority would be to make the locomotives look presentable and so we set to work sanding down the bodysides and repainting each locomotive.
For now we contented ourselves by replacing missing windscreens with Perspex sheets – even in 2004/5 genuine main line standard class 50 windscreens were some £1,000 each and replacing all four windscreens per locomotive was a cost we could not justify at the time.
We held a poll of our members to decide the new livery for 50030. The winner, by some margin, was ‘large logo’ British Rail (BR) blue with a grey roof, the typical early 1980s colour scheme for a Class 50. For 50029 we decided as a publicity stunt to repaint the locomotive in a similar livery but with a black roof and disguised on one side as its long-scrapped classmate 50003 Temeraire. In an additional act of silliness and in tribute to the England footballer of the time, we temporarily doctored the nameplate on one side of 50029 to read Roonown.
Pressing mechanical matters
We knew from our initial surveys of 50029 and 50030 that without major expenditure we could only make one good engine/main generator set. 50030 had been withdrawn following main generator damage and the engine in 50029 was seized. We made a start on overhauling the diesel engine in 50030 which was complete but had very high engine hours. This engine would need a complete rebuild with new bearings on the crankshaft and both ends of all 16 conrods, as well as all 16 pistons needing overhauling with new rings. The damaged generator would still need repairing at a potentially very significant price.
A fortunate development came to our rescue. After initial preservation by Pete Waterman, classmate 50008 Thunderer was bought by Sea Containers (SeaCo) who at the time operated the Great North Eastern Railway rail franchise from London Kings Cross to Leeds, York, Newcastle and Edinburgh. SeaCo had conducted a thorough overhaul of 50008 including replacing its engine/main generator set with a reconditioned ‘zero hours’ pairing. A combination of factors caused SeaCo to declare bankruptcy in October 2006 and their assets were to be sold off.
Following enquiries, we were able to purchase the engine/main generator that had been removed from 50008 prior to its overhaul. While the engine side of it had high hours and required a complete overhaul, the main generator was in good condition and this engine/generator combination is destined for use in 50030. The engine formerly inside 50030 will be combined with the good main generator inside 50029. This saves us the trouble of having 50029’s seized engine examined and avoids the prospect that it might not be repairable.
Small generators
In addition to its main generator, driven by the engine to provide power to the traction motors and move the locomotive, a Class 50 has two small generators. One of these is the auxiliary generator which creates 110V DC and is used to power systems such as lighting within the locomotive and electrical machines. The other is the electric train heat (ETH) generator which notionally provides 850V DC to power heating, lighting, hot water and, optionally, air conditioning in the passenger coaches.
However the radiator fan in a Class 50 is also powered from the ETH generator, which means that if the locomotive is hauling a load such as freight that does not require train heat, the ETH generator is always in use and will not ‘glaze over’. During Operation Collingwood’s ownership these small generators had been the subject of unwanted attention from copper thieves and were badly damaged.
Luckily the auxiliary generator is the same as that used in BR’s Class 37. Large numbers of 37s were going for scrap in the mid-2000s and we were able to purchase good condition aux generators as a result. The ETH generator is, however, unique to the Class 50. We were fortunate to strike a deal with the owner of a good condition ETH generator and resigned ourselves to a bill to get one of the damaged ETH generators rebuilt when we need it.
Train braking systems
Class 50s were introduced at a time when BR was transitioning from vacuum-braked trains to air brakes. On a steam locomotive it is easy to generate a vacuum by use of a steam ejector. In practice, two are used: one large ejector to exhaust the train brake pipe (this is responsible for the characteristic hiss and jet of steam as a steam train sets off from a stand) and a small ejector to maintain the vacuum whilst the train is moving. The system is failsafe in that the train brake pipe must be evacuated to release the brakes and air readmitted to apply the brakes. Should the train split in two, the vacuum would be destroyed and the brakes applied automatically.
In the early 20th century the US company Westinghouse held a number of patents on air brakes and so the ‘Big Four’ interwar railway companies in the UK standardised on vacuum brakes. Vacuum brakes are less efficient than air brakes because the maximum pressure difference obtainable is that between atmospheric pressure and a perfect vacuum. However, on a diesel or electric locomotive the operation of air or vacuum brakes makes little difference – both require an electric pump.
Class 50s have two exhausters for vacuum brakes and two air compressors – one compressor for the train brakes if hauling air-braked stock and the other for the locomotive brakes. If hauling vacuum-braked stock only one compressor is needed but they can both operate either train or locomotive brakes. While vacuum brakes are obsolete on Network Rail, heritage railways have acquired large fleets of vacuum-braked passenger coaches where they complement the use of vacuum-braked steam traction. Working vacuum brakes are therefore essential for a locomotive to be useful on preserved lines.
Brake system electrical machines
When restoring 50029 and 50030 we decided upon a strategy of ensuring they would be reliable and dependable machines for heritage railway use. We decided that the locomotives would receive fully overhauled electrical machines including the brake pumps. We had a stroke of luck, again, as Unipart Rail in Doncaster approached a number of preservation groups, including RRRG, offering surplus/obsolete stock at keen prices. We purchased a couple of good condition brake compressors and exhausters amongst other parts; these too went for electrical overhaul.
The electric motor end (left) and cylinder block (right) of a brake system air compressor seen partway through overhaul and after overhaul at our contractors.. Photos: Mark Burrows
The traction motor blowers received similar treatment. These electrical machines blow air over the traction motors to cool them and there are two per locomotive (one per bogie). Such motor blowers were partially responsible for BR’s infamous and embarrassing ‘wrong kind of snow‘ in 1991. With these electrical machines now overhauled, it was time to turn our attention to other items.
The electric motor (left) and ‘snail’ housing with fan (right) of a traction motor blower during overhaul at our electrical contractors. Photos: Mark Burrows
