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LIMA CLASS 31 (fitted with Hornby'Railroad' motor bogies) by PAUL JAMES


I had been looking for alternative ways of powering some of my Lima Class 31 loco's running on Wibdenshaw. Some have been double motored by splicing the relevant sections of chassis together, but having run out of doner parts and associated EM conversion wheelsets, the expanding Hornby 'Railroad' range caught my eye. I had already converted some of my DMU fleet with the new type of motors, so a suitable loco from the fleet was selected for a trial conversion using the co-co motor bogies available on the Railroad class 37.


A hole was cut in the chassis 75mm long by 24mm wide to accept a motor at the non-powered end, with the pivot points needing to be 58mm from the centre of the chassis.


The mounting brackets for the two motors are fabricated from 2mm thick plasticard, fabricating the 4 side supports 25mm X 18mm high, and the 2 cross pieces 25mm X 30mm with a centre hole just large enough for the spigot on top of the motor to push through (but not drop out). I drilled out to just undersize, and then using a round file opened up the hole until the motor was a gentle push fit.


A close-up view of the mounting bracket showing a half-round packing piece between the motor bogie and the cross piece (fixed lengthwise in line with the chassis), to allow the unit to pivot and adjust to any track irregularities.


There is another half-round section on the other motor mount (shown by dotted line), which is fixed across the chassis and allows the motor to pivot fore & aft, and effectively giving the loco an articulated 3-point suspension.


The Hornby motor bogie footprint is not as large as the original Lima unit, so allows the buffer beam to be removed from the chassis and fitted to the body. This view shows the new strengthening beam on the end of the chassis to ensure rigidity.


There is also enough room to fit a Hornby class 31 cab interior. Bufferbeam detail has been added (sprung buffers, air pipes, MU jumpers and sockets), available as spare parts here Front corner footsteps are fashioned from brass angle section, and the Hornby class 50 ETH jumper cables and box are used, with a cut-down electrification warning sign applied.


As the motor bogies were intended to power a class 37, new side frames would have to be fitted. Plenty of Lima unpowered bogie frames were in my scrap box (from previous double motor conversions), and aren't too difficult to obtain secondhand.


The centre section of the Lima bogie frame was cut out, leaving the side stretchers in place and making sure that enough of the end block is retained to clip over the locating lugs on the motor bogie. This is the only tricky bit, as just enough has to be removed to allow the Lima bogie to fit onto the Hornby unit, and with enough left to clip over the locating lugs.


Modifications to the Hornby unit consisted of adding some plastic strip to stop the bogie frames sitting too high. The Hornby plastic is the 'soft & soapy' type, and difficult to glue without roughing up the surface beforehand. Superglue does the job, although care has to be taken not to glue the two halves of the motor bogie together, as it's designed to split for repairs and maintenance.


One of the completed motor bogies ready for fitting to the chassis.


The loco has been tested on both Hornsey Broadway and Shenston Road, with both layouts having suitable gradients for testing 8+ coaches in tow. Some lead weight had been added inside the battery boxes, with some already fitted in the loco body, providing that essential weight for haulage and roadholding. All in all, it's been an interesting project that's injected a bit more life into a 20+ year old model, which is still held in high regard against the more modern offering.


The prototype seen at Kings Cross in 1981, with later added fan cowling on the roof.