Detailing of 4701 has continued and is now almost complete. Given the size of the loco plus the very tight radii it has to negotiate trial running at almost every stage of the build has been essential. In the past week some five hours of trialling has been required! Generally the running was OK but not surprisingly a number of issues were identified which needed rectification, principally the pick-up arrangement and pony truck.
As mentioned previously the fully compensated engine frame was constructed by David Amias who had installed current collection on all driving wheels via contacts on the rear of the wheels. These could cope with the huge amount of sideplay while acting as springs to keep the alignment of the frame generally as it should be. In service they proved to be overly flexible and kept fouling the spokes and being pulled out of alignment. To overcome this issue I fitted wipers onto six of the wheel flanges. Issues with the pony truck appeared to be insufficient sideplay with the wheels rubbing on the back of the leading cylinder relief valves plus an ATC shoe I'd soldered too low and struck point blades. Both issues were easily rectified.
With a completely new pick-up arrangement another emergency trial was arranged, only half an hour would be needed. Wrong! This session lasted almost three hours. Buoyed up by the fairly good running the previous evening the loco was put on the track and moved off. Almost immediately it started to derail at the most obscure of places. Most of the derailments concerned the pony truck so it was decided to run as an 0-8-0. With the loco back on the track it ran reasonably well but a short kept recurring but where? This proved to be in the area of the third axle. It was decided to strip the engine down completely and as tender and engine frame it ran perfectly.
Next the body was put back onto the frames and bolted down. Derailment followed plus increased shorting out. Eventually this was narrowed down to the throatplate striking the back of the wheels on the third axle. Out with the Dremel and the offending areas ground down. With the loco reassembled it ran perfectly as an 0-8-0 so now to try the pony truck. 98% perfect running has been achieved but the pony derails at one location in one direction only. Very frustrating, the pony truck is quite weighty, the pivot is not restricting movement but one wheel still rubs against a relief valve. The latter is easily dealt with but why does it continue to derail? This is an ongoing issue, can anyone suggest a solution? Back at home 4701 has reached this stage, very dirty from constant handling I'm afraid.
After all these problems a change of loco was necessary so out came the D1 and further progress on the frames has been made. The kit includes inside motion which is best described as basic, however it fills a void. Here are just some of the parts
![Valve gear 1 140516.JPG Valve gear 1 140516.JPG](https://www.westernthunder.co.uk/data/attachments/54/54868-d877d082f366da12ce52f2ee3ebe6ef8.jpg)
This little lot has taken over four hours to build up into what at best can only be called a representation. I am adding some more details although they won't be noticeable once the boiler is in place. The build instructions were brief but adequate although I used a GA drawing to construct the "unit".
![Valve gear 2 140516.JPG Valve gear 2 140516.JPG](https://www.westernthunder.co.uk/data/attachments/54/54869-d6b6b67498c19b16064f66426362dd13.jpg)
This has been followed by detailing of the frames with springs, brake gear, sandboxes and other parts fitted. Wiper pick-ups on the flanges have been installed and trial running may start later today, overall there is a 10 wheel pick-up arrangement including the tender.
Tomorrow I plan to start building the running plate and then address the frame profile issues identified by Steph a few days ago.