Restoration diary

As long-term followers of RRRG will know, for some time now we have been investigating the remanufacture of CU2 field divert units to replace the ones missing from our locomotives.  Our contractors for the job, Industrial Electronic Services Ltd, had analysed a genuine CU2 kindly loaned to us by another Class 50 owner and were confident they could reproduce the circuitry and components in the unit, using modern equivalents where possible/necessary.  They had however hit quite a snag when it came to replacing the little relay in the original unit.  The CU2 is a really amazingly compact piece of equipment for mid-1960s electronics as seen in the photo of the loaned unit below.  The relay in question is the small black box seen in the centre of the picture.  It switches at the operating voltage of Class 50 auxiliaries, namely 110v DC which brings about the problem of how to find a modern equivalent.  Electronics is obviously one area where technology has progressed leaps and bounds in the near-half century since the Class 50 was constructed by English Electric and relays to operate at such high DC voltage, let alone such compact ones (it appears the original was custom-made for EE by ITT) are almost completely obsolete these days.  Most modern relays, even of a size too big to fit the case, would burn out very quickly if asked to switch 110v DC.

We thought about various ways to overcome the problem.  Inverting the current to AC, using an AC relay and then rectifying it back to DC was suggested but dismissed as impractical.  50030 Electrical Officer Andy Rowlands suggested using a spare NR28 relay, as used elsewhere in the locomotive to switch 110v DC.  It wouldn't fit in the box for the CU2 (and the CU2 is deliberately designed to be compact as it fits into a very tight space in the cubicle) but Andy reasoned it could be mounted externally and wired in.  We supplied IES with a couple of NR28s to test the theory and they agreed it would work but felt the new divert unit would need some circuit modification if it were to be used.  IES decided to have another look at the relay market and managed to source a relay from the US which has a 24v coil and can switch up to 220v DC.  IES ordered a number of these relays on our behalf and have now advised us that they have arrived and appear to work fine in our 110v DC application.

We now expect progress to be rapid on the rebuild of these electronic units.  IES have invited Andy to inspect the new relays in person the first week in March and if approved by us, IES expect to finalise the design within the next couple of weeks with production of the two units requested following imminently thereafter.

A full description of the electronic units in a Class 50, and how many of each type RRRG has, can be found in RRRG newsletter Issue 23 (Autumn 2011).  Since that article was written, we have acquired one original CU2 from another Class 50 owning group however we still intend to have two units built by IES to cover for possible future failures.

A large amount of heavy boulders blocking the path to the container where our purchased spares were.

On Friday 29^th June 2012, Sarah and myself set off together with our trusty hound Toby to meet up with the contacted transport company at a site near Worcester to collect electrical items we had purchased from 50021 Rodney Group, this also included a Radiator Fan Motor and Traction Motor Blower for the D400 Fund.

When we arrived at site, we introduced ourselves to the Lorry Driver Nigel Chapman. The first problem we encountered was that due to the heavy deluge the day before, a delivery of large boulders had been delivered and dumped in front of the grounded curtain-sided truck body that our items were being stored in.

After a little head scratching it was decided we could get into the other side of the body if we removed the site security fencing. When we obtained access to the other side of body, the next obstacle was to release the tensioning mechanism, which through the passage of time had sunk into the ground, and after some digging with spades and persuasion with the site dumper truck which lifted the sunk body out of the ground we gained access.

We moved some fencing to gain access to the other side of the container.

With the transport lorry manoeuvred into position and stabiliser legs down the next problem encountered was a temperamental hydraulic hi-ab which with the technical know-how of Nigel, eventually played ball. The first two items strapped up and lifted out were the Cubicle and Rad Fan Motor. The two compressors and traction motor followed soon after. The items were secured down and we then drove to where the traction motor blowers and spare power unit (ex-50045) were stored. One blower motor was lifted and secured down.

We needed the site dumper truck to force our way in...

RRRG's main purchase, the electrical cubicle, safely loaded onto the lorry.

Once everything was checked to be secure we set off on our journey North, up the M5, M42 etc heading for Derbyshire with Bowers Electrical being our first port of call. We had anticipated the journey to be difficult with the usual Friday afternoon traffic, however also had the added problem of road closures along the A6 between Derby and Rowsley due to the Olympic Torch relay, fortunately the journey went without delay or incident. At Bowers we had the assistance of a forklift and very quickly off-loaded D400 Fund's Rad Fan Motor and Blower Motor together with our two compressors.

RRRG's haul included two genuine Class 50 compressors, ex-50011, seen being guided onto the lorry.


We then set off for Rowsley, arriving at site about 4:45pm, where we were met by local “BG” resident Dave Rolfe. Once on site we discovered one of our ETH generators (in worse condition than the others, which is why it was never sent for overhaul) was obstructing the route of the lorry to our storage shed, incidentally we also needed this moving, so with the Hi-ab on site we took advantage and relocated it dropping it near Renown together with the Traction Motor.

A further spare traction motor was also included in the deal.


A short break was had whilst we retired to the BG for a brew. Once refreshed we returned to our storage shed to off-load the electrical cubicle although this was not without problems as the hi-ab could not manoeuvre the cubicle all the way into the shed so with a solid steel bar and some brute force we pushed the cubicle in. Space in the shed being what it was, we had to man-handle the cubicle in at an angle until the doors could be closed and locked.  Everything was then sheeted up, secured and we eventually left for site calling at Frankie & Bennies for a very well earned bite to eat and pint, eventually getting back home some 15 hours after starting out earlier that morning.

After some manhandling to make it fit the available space inside RRRG's designated facility, the newly-purchased cubicle was safely stored awaiting future work. With this final act, a long and satisfying day finally came to an end!

A big thank you to Nigel Chapman the jovial lorry driver, who was a tremendous help on the day, enjoy your retirement!!  Photos by Sarah McCall.

RRRG has just purchased a traction motor, two compressors and an electrical cubicle (all ex-50011 Centurion) from the 50021 Rodney group/ owners . The items will be collected, together with items bought by the D400 fund, and transported to Bowers Electricals Ltd. at Heanor for assessment and any work that may be needed.

The  electrical cubicle that has quite a few re-usable components will be dropped off at Rowsley where the parts will be stripped for future use or spares.

Back in 2002 when RRRG successfully bid and secured Renown and Repulse together with various spares David Phillips was a volunteer at Pontypool & Blaenavon Railway and safely stored a CU1 on our behalf. As Sarah & I were travelling down to Swanage diesel gala this weekend to enjoy recently restored 50026 it was decided to call in to David's home in Trowbridge to collect the CU1 en-route. Whilst there I received a bonus in the form of an Ammeter for one of the cabs. I would like to thank David for safely storing the parts and also for the hospitality he and his wife offered us.

CU1 collected from David Phillips	CU1 Wiring Loom and Plugs	Cab Ammeter

Preliminary discussions have been engaged in with a good contact who can overhaul KV10s.  RRRG has a good number of both KV10s and their control cards in our possession but we have no idea if any or all of them are actually serviceable!  For the uninitiated, a 50 has two KV10s: one controls the main generator field strength and the other the ETH generator field strength - the difference being the control cards in the KV10 which define its function (main or ETH generator).  We understand this same contact can overhaul CU1 control units (the "master brain" of a 50) and we hope to have more news on these electronic component overhauls in a month or so.