RMweb Gold Stubby47 Posted March 21, 2015 Author RMweb Gold Share Posted March 21, 2015 Nope, it's exactly the sort of post that fits on this thread ! As I've said before, if wagon kits only had three wheels I could make them all reach the rails. Four wheels is much trickier, so to scratch build a 16 wheel loco..... Link to post Share on other sites More sharing options...
RMweb Premium uax6 Posted March 21, 2015 RMweb Premium Share Posted March 21, 2015 Yes and it actually leads to all sorts of issues... What is the minimum radius that she needs to get round? This will have a direct result on how you arrange the leading and trailling bogies for instance. You will have to do some experimentation with some mock up frames. The ideal way of mounting the bogies is to have them on a pin with a small amount of side-play (and some springing to act as side-control, so always trying to keep the bogie pivot along the centre-line of the chassis. This will then make the bogie steer the loco correctly into the curve). If this won't work on your bends, you will have to have them on Hornby style drag links, which will remove the steering effect either completely or with a link from the centre-line of the bogie engaging with a wider loop hung from the body, will empart only a small amount of steer.... Then you will have to have plenty of sideplay in the drivers as well.... Not the easiest loco to build! Andy G Link to post Share on other sites More sharing options...
RMweb Gold Stubby47 Posted March 21, 2015 Author RMweb Gold Share Posted March 21, 2015 Phew ! My simple thinking was this : If a 6 coupled loco, such as a pannier, can negotiate points & curves without any bogies or pony trucks , then so should an 8 coupled fixed frame. As Mike Edge has pointed out on his diagram, the two Fell outer bogies were standard 7MT ones, which can be bought as replacement spares for the Hornby Britannia. So, the bogies would be merely cosmetic-ish and the main chassis would look after itself. Possibly ! Link to post Share on other sites More sharing options...
RMweb Premium uax6 Posted March 21, 2015 RMweb Premium Share Posted March 21, 2015 Ahh, so you will be going for the 'toy' approach of the bogies just being there because they have to be. 'Tis a shame, as with just a tad of work you can make them do the job that they should. A good example of an easy mod is shown in Ben Alders black 5 workbench thread/blog. Such a big improvement for a small amount of effort. Do the 7MT bogies have pick-ups? If they do it will be a big bonus! Andy G Link to post Share on other sites More sharing options...
Popular Post brian daniels Posted March 21, 2015 Popular Post Share Posted March 21, 2015 I built the Fell in 7mm from a Jim Harris kit that was just a blow-up of the A1 job I think. I have kept it in sync by using delrin chain and cogs to connect the two halfs. 20 Link to post Share on other sites More sharing options...
RMweb Premium Sidecar Racer Posted March 21, 2015 RMweb Premium Share Posted March 21, 2015 Why ? I could still add short rods one side and a long 4-wheel rod the other. All the wheels should turn at the same rate, I think. In theory you could have long rods on both sides as in model form at least it will just be like an 8 coupled steam loco , I assume the real one had it's problems due to slip in the gearbox's . Link to post Share on other sites More sharing options...
RMweb Premium Sidecar Racer Posted March 21, 2015 RMweb Premium Share Posted March 21, 2015 Ahh, so you will be going for the 'toy' approach of the bogies just being there because they have to be. Sorry , but I think that is a bit harsh , Stu has already said he has NO experience of loco building so he is looking at a simple beginners way , I would and to some extent still do even though I've built several kits . 2 Link to post Share on other sites More sharing options...
RMweb Gold Stubby47 Posted March 21, 2015 Author RMweb Gold Share Posted March 21, 2015 Thanks Mike, but I think it's a fair comment. I could do it the way I suggested, because I know no better. But if experience of others shows a better way, and I think I can achieve that higher level of engineering, I ought at least to consider it. I might still make it a static model..... 3 Link to post Share on other sites More sharing options...
RMweb Premium Clive Mortimore Posted March 21, 2015 RMweb Premium Share Posted March 21, 2015 Hi Stubby Make it a 4-8-4, you can always change one side to 4-4+4-4 arrangement at a later date to see if that would work. Allow all axles some side play and use jointed coupling rods. I another idea, a wee bit more engineering, would be to have the motor drive a set of spur gears, which in turn drive a lay shaft with worm gears for the two inner axles. This should keep the two sets of 4 coupled wheels synchronised. 4 Link to post Share on other sites More sharing options...
RMweb Premium Clive Mortimore Posted March 21, 2015 RMweb Premium Share Posted March 21, 2015 This may be better for weight distribution. 3 Link to post Share on other sites More sharing options...
Andy Reichert Posted March 21, 2015 Share Posted March 21, 2015 Hey, Just use two power bogies for the ends, and let the centre just free-wheel. With those high hoods, you could fit just about anything. Andy 2 Link to post Share on other sites More sharing options...
Dr Gerbil-Fritters Posted March 21, 2015 Share Posted March 21, 2015 I built the Fell in 7mm from a Jim Harris kit that was just a blow-up of the A1 job I think. I have kept it in sync by using delrin chain and cogs to connect the two halfs. Brian, is there a single diesel class you have't built? I am amazed at the quality and quantity of your output. Kudos! Link to post Share on other sites More sharing options...
cctransuk Posted March 21, 2015 Share Posted March 21, 2015 Not the cheapest of options, but mine will have a pair of High Level gearboxes on either end of a Mashima motor; that way, as a 4-4-4-4 the rods will remain in sync. Originally I bought an A1 Models Dinosaur Diesel kit of 10100, but the etchings were so far out, especially around the cab windows, that I sold it on. You told me some time ago that you have one of these in your 'to do' list; hope that it arrives whilst I am still of this world !! (Only kidding, Mike). Anyway - there's nothing stopping me from getting on with your 11001. Regards, John Isherwood. In the light of the debate around producing a model of 10100, and in the hope that it will stimulate the production of Mike's kit, I reproduce below the drive arrangements that I developed for the A1 Models kit. The motor is a Mashima 1620 and the gearboxes are High Level. The main flaw in the design, IMHO, is the use of the flywheel as a splice between the motor shaft anf the drive shaft of the RH gearbox. This may well result in the whole caboodle shaking itself to bits - but then that might be prototypical too !! The green outlines are the A1 etchings, and a quick study of the area around the cab windows will indicate why I didn't proceed using that kit !! Regards, John Isherwood. 2 Link to post Share on other sites More sharing options...
Penlan Posted March 21, 2015 Share Posted March 21, 2015 Stubby, why not have a motorised four wheel van attached to the loco, and let that do all the work with the loco free wheeling... Simples....... Link to post Share on other sites More sharing options...
RMweb Gold Stubby47 Posted March 21, 2015 Author RMweb Gold Share Posted March 21, 2015 Nice idea Sandy, but I need to keep the two sets of wheels synchronised if in 4-4-4-4 formation ( which I could do of course if one side was 4-8-4).... Hmmmmmmm........... Link to post Share on other sites More sharing options...
AndyID Posted March 21, 2015 Share Posted March 21, 2015 Nice idea Sandy, but I need to keep the two sets of wheels synchronised if in 4-4-4-4 formation ( which I could do of course if one side was 4-8-4).... Hmmmmmmm........... If I understand correctly, you are considering coupling four wheels one side and not using a synchronizing gear? If so, I don't think that will work. You would have to couple all wheels on both sides to prevent the mechanism from locking. Link to post Share on other sites More sharing options...
RMweb Gold Stubby47 Posted March 21, 2015 Author RMweb Gold Share Posted March 21, 2015 I understand what you say, but am still not convinced..... Each set of 4 wheels has 2 rods, so will work as an independent unit. If the two sets are connected on one side, wouldn't the existing rods keep all the wheels in sync ? Link to post Share on other sites More sharing options...
cctransuk Posted March 21, 2015 Share Posted March 21, 2015 I understand what you say, but am still not convinced..... Each set of 4 wheels has 2 rods, so will work as an independent unit. If the two sets are connected on one side, wouldn't the existing rods keep all the wheels in sync ? Nope - if it did, you could get away with three rods on an 0-6-0. Even though the wheels are quartered, you need rods both sides to keep the wheels in sync. through the full 180 degrees. Regards, John Isherwood. Link to post Share on other sites More sharing options...
RMweb Gold Stubby47 Posted March 21, 2015 Author RMweb Gold Share Posted March 21, 2015 3 rods on an 0-6-0 would leave one wheel unconnected. This loco would have all wheels connected and running in sync in each set. Using a long rod on one side should keep one full side in sync, the other sides would be in sync in each of their sets. Gents, I'm not trying to be awkward here, I fully understand your view point and respect your experience. It's just the logical, theoretical part of my brain that would need to be convinced, either way, with a physical demonstration. Link to post Share on other sites More sharing options...
RMweb Premium Sidecar Racer Posted March 21, 2015 RMweb Premium Share Posted March 21, 2015 Here's an option for getting drive between the two 4-4 parts that would keep it in sync . http://www.mfacomodrills.com/pdfs/belts%20&%20pulleys.pdf Link to post Share on other sites More sharing options...
AndyID Posted March 21, 2015 Share Posted March 21, 2015 (edited) Hi Stubby, It's a bit difficult to explain why it will bind. Probably calls for a diagram, but I'll try it in words: Take the simplest case of four wheels with only one coupling rod on one side. All will be well as long as the axis of the rod is not in line with the axes of the axles (here be Vikings!). When the rod is in line with the axis of the axles (that's the same as the rod being half-way between its high and low travel) there is nothing to maintain the wheels at the same angle of rotation. In fact, it's actually possible for the wheels to start rotating in opposite directions! They won't rotate very far before they tend to lock up. Best, Andy EDIT: I forgot to mention that because the coupling rods are offset by 90 degrees (a quarter turn) one of them is always able to maintain the correct relationship between the axles even when the other one cannot. Edited March 21, 2015 by AndyID Link to post Share on other sites More sharing options...
RMweb Premium Clive Mortimore Posted March 21, 2015 RMweb Premium Share Posted March 21, 2015 Hi stubby Having seen John's idea for motorising it as a 4-4+4-4 where he was concerned about the linkage in the fly wheel, how about mounting the second gear box on the thrid axle and doing away with the fly wheel. Link to post Share on other sites More sharing options...
RMweb Premium Sidecar Racer Posted March 21, 2015 RMweb Premium Share Posted March 21, 2015 (edited) Hi stubby Having seen John's idea for motorising it as a 4-4+4-4 where he was concerned about the linkage in the fly wheel, how about mounting the second gear box on the thrid axle and doing away with the fly wheel. fell drive 3.png But will this work or will having the g/box's facing different ways cause one end to go forward and the other to go in reverse , or do the worms work in both directions ? Yes I know that they do , but that is when you reverse the motor , here we have a common shaft rotation but g/box's facing two ways . In other words , are there left and right leading worms or are they all straight ahead ? Or am I just confusing myself . It certainly would be a neat and effective solution though . Edited March 21, 2015 by Sidecar Racer Link to post Share on other sites More sharing options...
Horsetan Posted March 21, 2015 Share Posted March 21, 2015 If it's going to be a rigid chassis, why not have spur gears linking all axles, Ringfield-style. Link to post Share on other sites More sharing options...
N15class Posted March 21, 2015 Share Posted March 21, 2015 To me if Stu is going to build this as a 4-8-4 I would use a single motor and gearbox, flywheel if required. and as someone else said a Delrin chain between the two halves. Keep things simple. Link to post Share on other sites More sharing options...
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