Will L wrote:Getting it to Run.
The Gibson driving wheels have been quartered using the CW jig, as always. The gearbox is a standard Highlevel Loadhauler which, because the design of horn blocks used by the kit maximises the space available, just fits between the frames. Washers eliminated all the side play on the drivers. Only a modicum of opening out of crank pin holes in the rods was necessary and the chassis was soon bind free and turning over sweetly. All in all a nice bit of chassis design.
My only other mod was the up stand I used to attach the torque reaction link, the other end of which went through a hole drilled in the side frame of the gearbox. Bill does provide bits for this but no guidance as to how they fit. I’d gone my own way before understanding dawned.
Balancing the assembled chassis and loco
From the posts further back up the thread, you should have gathered that, as the bogie is separately sprung from the driving wheels, the available options for balancing the chassis resolve around placing the CofG some way forward of the classic “central over the CSB” position. Because the CSB on the driving wheels is a symmetrical 4 wheel arrangement, if the chassis sits level then the weight carried by all the driving wheels will be equal, which is just what we want. So the trick is to get the chassis sitting level. My available choices were either, to set the Loco CofG a fixed amount forward and juggle with the height at which the bogie supports the chassis, or, to adjust the position of the CofG of the loco. In either case you're done when the chassis sits level. Given the bogie modifications involved in fitting the pick ups, only the "adjusting the CofG" position option was really available to me.
For the sake of argument, I did a trial with the body weighted to put the CofG central over the driving wheels. In this state, the results were as you should have expected. The loco was visibly sitting high at the front. The pulling power was very limited, three relatively light bogie coaches had the wheels slipping on the flat, and it was inclined to derail at the slightest excuse.
Measuring buffer heights confirmed that the front of the loco was sitting markedly higher than the back, by more than 1mm at the top edge of the buffer face. So lead was added into the front of the boiler and between the frames over the bogie, until the buffer height was the same front and back. These measurements were not particularly precise, and the possible error could be a few 1/10s of a millimetre, but despite this, the haulage power and road holding were transformed. Now five much heavier coaches could be pulled up an incline with no problem. I’m still waiting to get access to a larger layout to find how big the load has to be before she starts struggling.
And that was it. Off she went to the paint shop, and when last seen she was earning her keep on Knutsford with no issues. All she needs now is lamps and a new layer of coal on the bunker!
CSB C12 veiw 1.jpg
And Finally
Here ends my planned posts to this thread, although I’m happy to discuss what I’ve done further with anybody who wants to. I hope this has sorted out the options for doing CSB’s on 4-4-0 loco’s and got it to the point where anybody else who wants to have a go can try it and be confidence of success.
One final word, I plan a post or two on the theory, when we might stretch a point and think about 4-6-0s too. I know a lot of you find the theoretical stuff more off putting than helpful, so they will turn up on another thread. After that it will be back to the J10 which requires a lot of non CSB related work.
Hello Will, having carefully bookmarked this topic for future CSB reading, I realised it might also help with a far smaller point I'm currently unsure about. I'm building an LRM C12 and amongst the included detailing are spark shields. They're even shown on the Isinglass drawing but it isn't quite clear exactly where they sit in relation to the cab window and its beading.
You show a couple of pictures of that excellent looking C12 early on in the thread, including what look to me like the very spark shields I've been agonisng over, but because the photos are quite low resolution I can't tell for sure, even by zooming in (no criticism intended, they look absolutely fine for normal viewing and I know I'm asking a lot to examine such small details in close-up!).
I realise you posted the pictures a decade ago (times flies...) but I wondered whether by any chance you still have access to the loco and if so, could you please post a close-up picture of the shields? Or did you might perhaps keep high resolution versions of the pictures you took at the time?
I've already collected several dozen C12 pictures from the famous Interweb but aside from those two of yours, I've found no others so far that show this small but interesting detail. Neither have I so far turned up anything in my own library, though every time I start going through another book, I get distracted by all the other lovely photos...
Thank you in advance,
Chas