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Many thanks indeed to Mike Boyle who has kindly written to us with an excellent report of installing Protocab in a Lima Class 73 loco. Mike writes:

The reasons for choosing the Lima class 73 (‘photo 1, cover photo above) as a starter loco are:-


1. It is generally available on the second-hand market at a reasonable price and so replaceable in the event of a disaster.
2. It is easy to dismantle and re-assemble both in terms of body from chassis and glazing from body. This means you can acquire and ‘swap’ bodies if you want to.
3. There is plenty of free space inside so that different arrangements can be contemplated.
4. Being an electro-diesel means that it has a wide potential in terms of both period and location.

Once the body is unclipped and the body shell and glazing shell separated (‘photos 1 and 3) it becomes apparent that some parts of the installation have been made easy by the design and construction of the model itself.

Photo 2: Photograph (c) 2018 Mike Boyle

Photo 3: Photograph (c) 2018 Mike Boyle

A great bonus is the gap between the glazing shell and the ballast weight where the battery can sit on a metal heat-sink and be retained by shortening, as appropriate, the two columns extending down from the glazing shell to prevent the ballast weight itself from shifting during use (see ‘photo 4). Since the battery rests its entire lower surface on the weight I have not taken the precaution of insulating it (as per Tony Hagon’s advice in the Youtube installation videos) because the weight can act as a heat-sink which is considered desireable in the installation instructions. Also, because of the restraining columns, air can easily circulate over the upper body of the battery. The snug but adequate fit of the battery in this space means that it really is the only place worth putting it and the extra weight can only assist the ballast in improving traction.

Photo 4: Photograph (c) 2018 Mike Boyle

The second design bonus is the arrangement of the non-power bogie which can be gently pulled downwards from the body against a light spring which then allows it to be rotated through 90 degrees across the line of the body. This, in turn, allows the exposure of a big enough area of floor to accommodate the body of the charging plug thus providing a well concealed but easily accessed site for the charging socket (‘photo 5). In order to achieve this the pcb containing the socket needs to be mounted diagonally in the body space so that the protruding socket can be located by drilling carefully through the floor to offer a securely located socket to the outside but with no protrusion beyond the bottom of the floor. Co-incidentally the thickness of the floor is exactly right to achieve this! At the same time another smaller hole should be drilled through the floor so that the red/green charging light (mounted on the same pcb close to the socket) can be observed through the floor (see ‘photo 5) to help regulate the charging process.

Photo 5: Photograph (c) 2018 Mike Boyle

The only problem I have found with the charging process is the significant force required to both engage and dis-engage the charging plug from the socket. This requires that the pcb be located very firmly and carefully (see again Tony’s Youtube video on installation) to avoid any potential damage.

Photo 4: Photograph (c) 2018 Mike Boyle

I have done this by gluing small chunks of pvc to the floor on each side and at each end of the pcb (‘photo 6) so that it cannot move laterally and then gluing small sheets of pvc to the underside of the glazing shell (‘photo 2) until they just retain the pcb vertically (against the insertion forces) and so prevent the socket escaping into the interior of the body. The glazing shell itself is prevented from moving upwards by several nibs that bear against the underside of the roof.

The other pcb, the lcu, is small and can be easily located in the remaining space at the non-powered end of the model. Since it is extremely small and light I have simply attached it to the floor with a small piece of blu-tack (‘photo 6) which would simply give way if any pressure was encountered during the re-mounting of the body and glazing shells.

Apart from removing the original connections to the motor and replacing them, as instructed, with the new lead supplied I think it is worth dismantling the non-power bogie since the brass retaining clip inside the body is electrically connected to the rail beneath but can be isolated by the removal of a phosphor-bronze ‘spring’ joining the axles to the bolster. In theory this is unnecessary but you never know what might come along the rail in addition to 12v dc or 16v ac and wave its magic wand around next to your delicate control gear. The clip itself retains the bogie but is also quite large and I have used two more chunks of pvc (‘photo 2) to restrict its movement inside the body to avoid any contact with the delicate components on the two pcbs.

That leaves the proximity switch on the copper sheet which I have mounted above the glazing shell attached to the bottom of the roof (‘photos 7 and 8) where it works perfectly well away from any physical interference and the motor at the other end.

Photo 7: Photograph (c) 2018 Mike Boyle

Photo 8: Photograph (c) 2018 Mike Boyle

Wiring is allowed to find its own routes to a degree but restrained, where necessary, by small pieces of masking tape to avoid any pinching on assembly. There are enough windows in the assembled loco to allow the blitz light on the lcu to be observed in operation so that you know when you have woken your loco up.

The loco now operates ‘as advertised’ and can be seen in ‘photos 9 and 10 putting in its first appearance at an exhibition as a guest on a dcc layout at the show in Barton Peveril in January. Some of the punters were quite impressed with the new ‘magic’ loco!

Photo 9: Photograph (c) 2018 Mike Boyle

Photo 10: Photograph (c) 2018 Mike Boyle

There is one remaining advantage to the relatively complex fitting arrangements used here. With the exception of the soldered motor leads everything can be easily removed for adjustment or repair and could actually be fitted to another locomotive at a future date. I can certify that no components were modified or harmed in the installation process.

One thing I am sure of, though. Time spent measuring and planning before installation is definitely not wasted.

For the future I am now looking at installing Protocab in a class 123 DMU (large guard’s section) which has yet to be built and after that I might be ready to tackle the squeeze involved in the tender of a steam loco (see Tony’s videos again). Perhaps I should measure up a GWR 4000 gallon job – they used to run behind quite a lot of different classes right down to the Collett Goods ( yes, I know, but there are several ‘photos).

Text and Photographs (c) 2018 Mike Boyle






Page last updated: 28 May 2018