Southern Electric Group 4Cor unit 3142 Preservation Report 9

4 COR Preservation Report Summer 2001

At the end of the last report you may remember that we had just come to the painful decision to remove the front corner panel on the drivers side because of rot in the wooden frame under the top of the panel. The rot in the woodwork turned out to be much less serious than we originally feared, water had seeped into a joint where a repair had been carried out following an accident in the 1950’s. We made an iroko (hard wood) patch which was, glued and bolted in place similar to the many we have completed on the main bearer at the bottom edge of the frame.

The metal panel itself however turned out to be in a rather worse state, so we used a spare panel to replace the original. This replacement was the remaining half of a pair which were made professionally at least 10 years or so ago, one of the front corner panels having been replaced on another motor coach (11201), while the unit was still at Preston Park.

The construction of the panel is quite interesting. The originals were pressed (or beaten?) into the correct shape which inevitably curves in two directions at the lower end, as it goes round the front corner and at the same time curves in following the tumble home of the side. Figure 1 shows how the replacement panel was cut and welded to form the correct profile. The method of producing the shape was to cut up the old original panel (from 11201), flatten the pieces and use these pieces as templates. The finished result shows no sign of joins, it is only after careful inspection of the inside that the construction is apparent. Note that the small sections are only necessary on the back edge as it is here that the curve in two directions occurs. The front of the carriage is of course flat.

All fine so far, but when it came to fitting the new panel we discovered that the two motor coaches must have been slightly different shapes! Fortunately the one we are restoring (11187) is the smaller. It became apparent that the wrap around at the front was too great and we had to carefully cut thin strips off until it fitted. This is no easy job using a hacksaw along a 7 foot length, it took two of us most of a day to get it right then re-drill the holes, but in the end it produced a very pleasing result. Another item that I touched on in an earlier article was the compressor this as you may remember was hauled into place reconnected, and started to pump as soon as power was applied. The problem was that not very much air was produced. A good piece of detective work however established that the problem was due to two of the valves being missing. This type of compressor is still in use on much more modern units including DEMU’s. Hastings Diesels Limited were able therefore to provide us with a couple of replacements. These were cleaned up and refitted, this time when the power was applied the air pressure started to build up as it should.

Inside the driver’s cab is the equalising pressure valve whose purpose is to switch the compressor off when the pressure reaches 100 psi. The compressor even with the fairly low voltage we are using proved well able to pressurise the system to this level, and sure enough as soon as the figure of 100 was indicated on the pressure gauge in the cab, the current was cut off. There are a few small leaks in the system and after a few minutes when the pressure had dropped back to about 95 psi, the compressor cut back in. We believe this is truly remarkable after so many years out of use. Now that we had air pressure we could start to look at the control gear for the motors. Control of the motors is achieved by means of electro pneumatic actuators which are located in a case under the centre of the coach. Inside this case the switching of load resistors in series with the traction motors is performed by air operated switches. Control of the air to activate these main switches is by means of valves operated from the 70 volt auxiliary supply. The air pressure involved in all of this is at 50 psi i.e. only half of that required for the brakes. A reducer valve is fitted to do the reduction, situated underneath the coach. At first this leaked rather, but after cleaning out, now works quite efficiently. The 70 volt control system to operate the switches is not at present in a working state but the valves to control the air operated main switches can be activated manually. All of these operate correctly but it remains for the 70 volt control wiring to be replaced before any more progress can be made on this part of the project.

One curiosity (to my mind) is the windscreen wiper, which we had to remove during the replacement of the front corner panel. This is also operated by compressed air, which seems odd for an electric train. It is not unlike the use of oil lamps on the rear of the trains, presumably in the days when they were built people were none to keen to trust this new fangled electricity. The windscreen wiper motor has now been cleaned up and freed (it was originally seized), but has yet to be replaced.

In an earlier article I described the restoration of one of the passenger doors. There are only four of these but in addition there are double doors on each side of the guards compartment, and a drivers door on each side. The double guard’s door on the blind (off) side has now also received similar treatment to the earlier passenger door. These doors are obviously similar to the passenger ones, except for the windows, and the internal panelling. The windows are of the older type held up by a leather strap, this of course necessitates the window being in a wooden frame. In their early days these window frames were varnished, but later were painted. We pondered whether it may be possible to restore them to the original finish, the wood is still in good condition, but many layers of paint are not easy to remove, also varnished wood is not really contemporary with yellow front ends. However we decided to have a go at recreating the old style, it is always possible to paint over it, if it doesn't look right. The best way of removing the old paint turned out to be paint stripper, heat guns are not good near glass and power sanders would probably damage the wood too much, even so after getting the bulk of it off with stripper some sanding was still required. Even with all of this done there is always some paint buried deep inside the wood grain. So we decided the best solution was to apply a dark stain before varnishing. We are quite pleased with the results, although it is almost certainly darker than the original. It does help to create a vintage atmosphere in keeping with its age.

The method of holding the window in the up position is very simple as may be seen in Figure 2. A right angled brass strip on the bottom edge of the window simply slips over a strip on the edge of the door frame. To close the window, it is hauled to its fully up position and then pushed forward over the strip on the door edge to hold it up.

The inside of the door is simply panelled in tongue and groove and painted, to match the inside of the guards compartment, none of the varnished wood of the passenger doors.

As with the passenger door it is amazing how much needs to be trimmed off after the door is replaced, it is almost as if the train shrinks as soon as the door is removed. It is not even that the hinges are worn or have moved as there is no appreciable gap on the hinged edge.

Work has also been going on inside the cab. The door inside the gangway (which folds back to close off the drivers cab during multiple unit running) has been taken off and the panelling replaced. This panelling is only thin plywood and was crumbling away at the bottom edge in particular. The new panel is now being varnished, not really authentic but adding a nice touch of class we feel.

Also inside the cab is an air reservoir above the driver’s window. This is probably to ensure that there is enough air available for the whistle or air horns. This has also been repainted in green. Switch boxes fitted behind the drivers seat have also been removed, cleaned and repainted. The doors of these having been repainted orange to indicate danger, again not really like the original but apart from its value as a warning also adds a bit of colour.

The longer term goal of the work in the cab is to re-install the controller to enable the contactors described earlier to be operated. As part of this rewiring the 12 way control cable has been replaced the full length of the carriage from the controller to the junction box on the rear. This involved using the old wire to pull the new one through the conduit (12 times!).

The last window has now been refitted in the passenger saloon. The glass in this one was fitted in situ, the frame having been replaced a couple of years ago. Normally glass would be replaced in this way and in fact it is just as easy to do it this way as with the frame out. It still remains to refit all the sliding top lights but this should be a much simpler job, all they require is to be cleaned and repainted.

One last job on the body sides was to replace the overlap strips where the body panels meet, there is one of these between all the lower body panels, a total of six per side, making a weatherproof seal over each of the vertical joints, see Figure 3. We could only find 11 of these originally and so had to make a replacement, and then as you can probably guess, as soon as they were all fitted the missing twelfth one turned up. The body is thus now ready for painting, red oxide is not really sufficient weather proofing, and odd spots of rust tend to show through. Gloss paint is necessary to keep the wet out completely, also I am sure it will lift our spirits to see it all in gloss green. We have now made a start on the painting which I will describe next time, but it certainly seems that it will be a pretty long job.

It has taken us about six years to bring the carriage up to the standard that it is now and although a good deal still remains to be done we know that it is within our capacity to do it.