Ruston Posted November 28, 2012 Share Posted November 28, 2012 Hello peeps, I'm hoping someone can give me some answers to a few questions regarding what will be a first for me. I have just bought a kit for a 7mm scale Hudswell Clarke 0-6-0ST. I've now built 4 locos with some form of compensation or springing but all have been of the 0-4-0 variety and it's obvious that only one axle needs to be made to move relative to the chassis. I find it neccessary to fit compensation or springing in order to maintain electrical pickup when you've only got 4 wheels in contact with the rails at the best of times... But I've never built anthing with more than 4 wheels before so... What about an 0-6-0? Do they need compensation, or are they OK as rigids? Then what are the options - which axles should be fixed and which should be free to move etc? Link to post Share on other sites More sharing options...
RMweb Gold Donw Posted November 28, 2012 RMweb Gold Share Posted November 28, 2012 0-6-0s can be built sucessfully as rigid chassis providing the track is fairly flat but compensated or sprung chassis work better. If you build rigid do make sure the centre axle not lower than the outer ones or it will rock. If you adopt compensation it is easier if one of the outer ones is fixed. If sprung and you use a motor gearbox you can spring them all. DO remember you need jointed rods for compensated or sprung chassis for best results. Don Link to post Share on other sites More sharing options...
davknigh Posted November 28, 2012 Share Posted November 28, 2012 Everything you wanted to know about suspension but were afraid to ask http://www.clag.org.uk/41-0rev.html Yes it is about 4mm scale but the principles apply to all scales. Cheers, David Link to post Share on other sites More sharing options...
davelester Posted November 29, 2012 Share Posted November 29, 2012 What about an 0-6-0? Do they need compensation, or are they OK as rigids? That depends. (On track standards and personal choice.) Then what are the options - which axles should be fixed and which should be free to move etc? One solution is to treat your 0-6-0 as an 0-4-0 and put light springing on the centre axle. The advantage is that you have a larger area in which you can place the Centre of Gravity, without the loco toppling over. Link to post Share on other sites More sharing options...
chaz Posted November 29, 2012 Share Posted November 29, 2012 Dave, I built my first 7mm 0-6-0T (an ex-LNER J50) with a rigid chassis. It ran well but was quite sensitive to dirt on the wheels. Eventually I rebuilt it with sprung hornblocks which transformed it. Now it only stalls when the wheels are really dirty. Later I built an 0-6-0ST with the leading two axles in rocking compensated beams. This also is almost dirt-proof. The advantage of beams over hornblocks is that they cost little - just the time involved in making them. You can use standard axle bearings soldered into the beams. I can post you more info' - including a snap or two - if you are interested. Another link for you... www.abcgears.co.uk If you find this, go to "downloads" and you will find a PDF which deals with compensation. Well worth a look. Chaz Link to post Share on other sites More sharing options...
Kenton Posted November 29, 2012 Share Posted November 29, 2012 IMO/E 7mm (O) track is more forgiving and so springing/compensation is less of a requirement - as the track standard gets finer in each scale then the small differences become more acute to both road holding and electrical pickup. I would always fix the driven axle in whatever arrangement. I hate over complication simply for fashion sake and I consider compensation and even more so springing an over complication. With often the movement well and truly exaggerated to the point of a wobble. If the track is that uneven the fix the track. Besides remember all that trouble you went to to get everything exactly lined up as a fixed chassis (jigs, graph paper, alignment bars) now multiply it ten fold to get everything to work when deliberately not lined up. I think it has been said somewhere before but I would rather have a sweet running fixed chassis than a poorly sprung one any day. Link to post Share on other sites More sharing options...
RMweb Gold ngtrains.com Posted November 29, 2012 RMweb Gold Share Posted November 29, 2012 But you don't need to do anything to your Ixion. A closer look will reveal it has some springing on (i think) the rear axle. This is enough to maintain electrical contact on average track. Link to post Share on other sites More sharing options...
JeffP Posted November 29, 2012 Share Posted November 29, 2012 Kenton, do you build all your chassis rigid then? Or do you introduce some form of compensation to some? Link to post Share on other sites More sharing options...
Kenton Posted November 29, 2012 Share Posted November 29, 2012 Kenton, do you build all your chassis rigid then? Or do you introduce some form of compensation to some? Probably 90% locos rigid (I do the occasional EM/P4 sprung) but most are 0-4-0 or 0-6-0 with a very high proportion of diesel shunters. For wagons oddly enough the vast majority are compensated, very few are rigid. I don't avoid build coaches. I guess this would be quite different if I built / had an interest in the P4/S4/S7 arenas but can't escape the fact that most people operate OO or O or OO9 (I shake'n'struggle too much in 2mm these days). Link to post Share on other sites More sharing options...
chaz Posted November 30, 2012 Share Posted November 30, 2012 IMO/E 7mm (O) track is more forgiving and so springing/compensation is less of a requirement - as the track standard gets finer in each scale then the small differences become more acute to both road holding and electrical pickup. I would always fix the driven axle in whatever arrangement. I hate over complication simply for fashion sake and I consider compensation and even more so springing an over complication. With often the movement well and truly exaggerated to the point of a wobble. If the track is that uneven the fix the track. Besides remember all that trouble you went to to get everything exactly lined up as a fixed chassis (jigs, graph paper, alignment bars) now multiply it ten fold to get everything to work when deliberately not lined up. I think it has been said somewhere before but I would rather have a sweet running fixed chassis than a poorly sprung one any day. Oh, so would I Kenton - but my preferred choice is definitely a sweet running beam compensated chassis. I am about to embark on an 0-6-0 and will be buying the kit tomorrow at the Reading trade show. I intend to build this with the front and middle axles in twin rocking beams and the rear (driven) axle in a rocking arrangement. If necessary I will modify the frame spacers to get the beams in. When it's done all six wheels will be in contact with the rails, so getting better adhesion and better pickup. Your trackwork is almost certainly better than mine but, even if it's nearly perfect (perfection is unobtainable to mere mortals), a lot of the time a rigid 0-6-0 will only have three of its wheels in contact. I have to conceed that it's more work to build a chassis like this but once done it pays off everytime the loco moves. My locos normally move off when I tell them to - occasionally they don't and that's the signal to clean the wheels and maybe the track. The difference is that the locos I have that are compensated are much less sensitive to dirt and I am often staggered by how filthy the wheel treads are when they finally stop moving. I'm not advocating neglecting a cleaning regime - merely making the point that rigid locos will inevitably be more prone to pick-up problems. Springing? It's OK, but more expensive if you are buying in hornblocks and, if you spring all six wheels, it's a real pain to adjust to get the loco to sit upright and level. Still, Rule One applies at all times..... Chaz Link to post Share on other sites More sharing options...
MarkC Posted November 30, 2012 Share Posted November 30, 2012 I like the Sharman "Flexichas" system for my 0-6-0s; and it works well for 2-4-0s too. I have also built a Brassmasters Deeley 0-4-0T with simple compensation - slightly uneven track is absolutely no problem for that one either, unlike 'fixed' 0-4-0s. I've not yet had the need to try Flexichas on other locomotives; however I've a couple of 4-4-0s & 0-4-4T kits to build, so may give it a go soon. To my mind, it's as much about having as many wheels in full contact with the rails for good pick-up of power, as it is for traction purposes. Mark Link to post Share on other sites More sharing options...
chaz Posted November 30, 2012 Share Posted November 30, 2012 I like the Sharman "Flexichas" system for my 0-6-0s; and it works well for 2-4-0s too. I have also built a Brassmasters Deeley 0-4-0T with simple compensation - slightly uneven track is absolutely no problem for that one either, unlike 'fixed' 0-4-0s. I've not yet had the need to try Flexichas on other locomotives; however I've a couple of 4-4-0s & 0-4-4T kits to build, so may give it a go soon. To my mind, it's as much about having as many wheels in full contact with the rails for good pick-up of power, as it is for traction purposes. Mark A 4-4-0 is a good proposition for beam compensation, Mark. The 0-4-4T is the tricky one. It can be done but the problem is that the driven axle is usually No 2. I did once see some 2mm finescale LSWR O2 tanks that had been built as if they had two bogies. The ran beautifully and you couldn't tell that the driving axles weren't fixed in line. Chaz Link to post Share on other sites More sharing options...
Sandy Harper Posted November 30, 2012 Share Posted November 30, 2012 You don't need to spend money on expensive horn blocks. See my 'Gordon Castle' and 'HR Loch' forums on this site to see how it is done. On a three axle chassis you would be wise to consider some movement of the middle axle to accommodate any discrepancies in your track. The dirt problem is caused because there is a momentary gap between wheel and rail and a spark will be produced which will 'burn' any dirt/dust and fix it to your wheel. If you can keep all your wheels in contact with the track you should reduce this to a minimum. The other option is to stuff your loco full of lead!! Good luck and keep us posted of your results. Sandy Link to post Share on other sites More sharing options...
Kenton Posted November 30, 2012 Share Posted November 30, 2012 0-6-0 with only 3 wheels in contact? I'm trying to figure this one out? In theory for electrical contact only one on each rail is critical - if clean wheels and track is a given (forgetting isolated plastic frogs because they have no place as far as I am concerned. (BTW my track is far from the perfection you might otherwise believe but clean it most certainly is) I could never support the concept of introducing the complication of compensation or springing simply to avoid the chore of cleaning wheels and track properly. I am also very suspect of compensation as a method of getting all the wheels in contact. AFAIC the only way is to fix one axle and to spring the rest, suffering the hell of hornblocks (hell - when these require any cutting of frames - fairly straightforward when the frames come designed and etched accordingly) Please though don't misunderstand me. I would so much prefer to have a sprung chassis than a fixed one but the majority of kits do not come that way. I find the introduction of such "nice to haves" into those kits a big hassle in both alignment (possibly as I have no fancy jigs), time (a fixed chassis can be up and rolling in a couple of hours anything else seems to take a day or more), not to mention cost as suitable hornblocks are not in the kit and not in the designer's mind at the time. Link to post Share on other sites More sharing options...
chaz Posted November 30, 2012 Share Posted November 30, 2012 0-6-0 with only 3 wheels in contact? I'm trying to figure this one out? In theory for electrical contact only one on each rail is critical - if clean wheels and track is a given (forgetting isolated plastic frogs because they have no place as far as I am concerned. (BTW my track is far from the perfection you might otherwise believe but clean it most certainly is) I could never support the concept of introducing the complication of compensation or springing simply to avoid the chore of cleaning wheels and track properly. Three wheels touching? Well not all the time! As the loco moves it will always be at least three (think of a 3 legged stool) - but microscopic variations in wheel diameter, rail level etc will ensure that a rigid chassis rarely, if ever has all six wheels touching. Electrical theory is fine, but if the only wheel touching the rail on one side just happens to encounter some dirt the loco stalls. I am also very suspect of compensation as a method of getting all the wheels in contact. I felt much as you do, but conversations with a couple of blokes who are much better engineers than I will ever be persuaded me. It's a fact that if all the wheels are allowed a small amount of vertical movement, and the loco is sufficiently heavy to overcome any inertia (and it doesn't take a boiler full of lead to do it) then all the wheels will be touching the rail. a fixed chassis can be up and rolling in a couple of hours anything else seems to take a day or more), not to mention cost as suitable hornblocks are not in the kit and not in the designer's mind at the time. Can't argue with that! Yes, it takes some time to make and set up compensation but I am sure it's time well spent. And as to the cost of hornblocks - I have stopped using them since I saw the light and switched to beams. I solder the axle bearings into the beams - but the other way round to those in a rigid chassis - that is with the flange inwards. But Rule One applies (thank goodness!).... Chaz Link to post Share on other sites More sharing options...
Kenton Posted November 30, 2012 Share Posted November 30, 2012 chaz, surely with a 6 wheeler the three axles would be equivalent to two 3-legged stools. I must admit to being the first to get confused between compensated and sprung chassis but I had always thought of the beam method you describe as being closer to compensation than springing - even when a torsion wire is used to apply downward pressure on the axle. The whole nature of the beast makes it overly complex and in the end hornblocks can be the simplest solution IF it is pre-designed into the kit as it sometimes is. But it is easy to forget that although simple in concept the extra time and parts can soon add considerably to the cost of a build. Regarding your comment on soldering the bearings into the beams - perfect sense - but once again how do you cope with the gearbox bearings - there is little enough space on most kits as it is, or are we once again only talking about widened frames as in EM/P4? Link to post Share on other sites More sharing options...
JeffP Posted November 30, 2012 Share Posted November 30, 2012 With beam compensation, how is the ride height altered? Or does it have to be carefully pre-set? Link to post Share on other sites More sharing options...
chaz Posted November 30, 2012 Share Posted November 30, 2012 With beam compensation, how is the ride height altered? Or does it have to be carefully pre-set? The latter, Jeff. In fact it is set by the position (height above the rail) of the beam pivots in relation to the the axle centres. I usually arrange mine so that the beam pivots lie on the same line as the driving wheel axles. Chaz Link to post Share on other sites More sharing options...
Ruston Posted November 30, 2012 Author Share Posted November 30, 2012 But you don't need to do anything to your Ixion. A closer look will reveal it has some springing on (i think) the rear axle. This is enough to maintain electrical contact on average track. It's not Ixion. I'ts a kit, an Agenoria Models kit. Thanks for the replies. Lots to think about and I guess the first thing will be to see if the rods are jointed or not. Hornblocks aren't a problem as I've got a lathe with a 4-jaw chuck and a milling machine. Link to post Share on other sites More sharing options...
chaz Posted November 30, 2012 Share Posted November 30, 2012 chaz, surely with a 6 wheeler the three axles would be equivalent to two 3-legged stools. I must admit to being the first to get confused between compensated and sprung chassis but I had always thought of the beam method you describe as being closer to compensation than springing - even when a torsion wire is used to apply downward pressure on the axle. The whole nature of the beast makes it overly complex and in the end hornblocks can be the simplest solution IF it is pre-designed into the kit as it sometimes is. But it is easy to forget that although simple in concept the extra time and parts can soon add considerably to the cost of a build. Regarding your comment on soldering the bearings into the beams - perfect sense - but once again how do you cope with the gearbox bearings - there is little enough space on most kits as it is, or are we once again only talking about widened frames as in EM/P4? OK Kenton, I will try to answer your points. Firstly let's get springing out of the way - with beam compensation, as propounded by Sharman (amongst others) there are no springs. The beams allow each wheel to rise and fall a little - half a mill' in each direction is considered ample - if it isn't you really do need to fix your track! The best way I can answer your other points is with a couple of photos of the underside of one of my locos - an 0-6-0ST. The first picture shows the front two axles. You can see one of the beams with the wheel bearings soldered into it. The rod you can see passing over the speaker is the pivot pin for the beams. There is a shortened Slater's crank pin bush on each end of the rod to beef things up a bit. The holes in the frames (which you can't see) have been enlarged to allow the wheel bearings to move up and down. So, the first two legs of our three legged stool are the two pivots in the middle of the beams. Now for the back axle... This engine has a rigid back axle - which is a bit of a compromise - which I will deal with in a moment..... That's an ABC gearbox - which fits nicely between the axle bearings with a bit to spare - you can glimpse a bit of axle between the gearbox axle bearing and the one in the frames. Now were the bearings in the frames to be reversed and put in a beam the gearbox would still fit - I know because I've done it. I said that the rigid axle is a bit of a compromise - it means that the third "leg" is the whole axle - the weakness of this arrangement is that if one of these wheels wants to move up or down the whole loco has to move. This is OK but it is theoretically not the best solution. A refinement (the Rolls Royce version) would be to put the axle bearings into two short beams pivotted somewhere close to the middle axle. These would move through a small arc to give each wheel a small amount of movement up and down. The level would be maintained by fixing a rod in the chassis at right angles to the axle against which it would rub. The net effect is to allow the axle to rock - which gives excellent 3 point suspension - the third point being the contact between the rod and the axle. BUT to do this you would have to turn the gearbox round and drive the centre axle. No problem - the gearbox is axle hung anyway. In the photo you can see a torque arm - a strip of brass soldered into the frame spacer. it has a D shaped slot filed in its end which fits around the steel pin in the gearbox. Using that, repositioned, would allow the axle to move and the motor to go with it. Remember, we are only expecting very small movements. Having said that this loco, with its rigid driven axle, is an excellent runner and the compromise appears to have very little effect. Sorry to go on a bit, but you did ask. I know it's tricky getting your head round this stuff - it took me a while to get it - but it is not a difficult as it looks and the result is a very reliable model that rarely stalls and has good adhesion. Feel free to post any other questions you might have - I'll do my best to answer them.... Chaz Link to post Share on other sites More sharing options...
Ruston Posted November 30, 2012 Author Share Posted November 30, 2012 I like the idea of beam compensation. I suppose the ultimate would be springs and beams, like the suspension on a Barclay 0-6-0ST. Link to post Share on other sites More sharing options...
chaz Posted December 1, 2012 Share Posted December 1, 2012 I like the idea of beam compensation. I suppose the ultimate would be springs and beams, like the suspension on a Barclay 0-6-0ST. Dave, IMHO adding springs to beam suspension would do nothing to improve a model, in fact it might well prevent the beams from moving as freely as we want them to. Remember that the springs on a real loco do several jobs, one of which is to lessen the shocks caused by poor track, rail joints etc which might otherwise cause damage (frame fractures, loosening the driver's teeth etc). We don't need to worry, our driver's teeth are white-metal! No, we can rely on gravity to make the loco sit on all of its wheels. I ought to say that springing can be made to work fine in 7mm - I have two six-coupled tanks locos which are sprung but, having seen the light, my next loco (a J6) will have beam compensation and no springs - easier and cheaper. Chaz Link to post Share on other sites More sharing options...
RMweb Gold Donw Posted December 1, 2012 RMweb Gold Share Posted December 1, 2012 Kenton it is quite easy for an 0-6-0 to be on only three wheels. As the loco passes over a dip the two centre wheels will be clear of the rails. So the loco should be on the four outer wheels If there is a slight bit twist in the track all four cannot be in contact the loco will rock on two wheels on the diagonal with one of t'other pair making contact.We are only talking of fractions of a millimetre here but it will be enough to cause sparking which increases the problems with dirt. Similarly if you go over a hump the two centre wheels can be in contact and the highest of the other four in contact will balance the loco. In practice the loco runs along with the contact intermittantly coming from different wheels. Run a loco round in the dark and you can usually see small sparks at the wheels even if it keeps going. Do the same with a well srung or compensated loco and the amount of sparking is greatly reduced. Is it extra trouble yes extra expense well for sprung hornblocks yes but there are inexpensive ways. Is it worth it yes. Having a plumbed in bath is more expense and work than the old tin tub I know which I prefer. In 2mm the most popular method is to increase the bearing diameter by about 0.1mm and add light springs pressing on the axles. These replace wipers on the wheels to collect current and the small amount of slop improves pick up. Don Link to post Share on other sites More sharing options...
PatB Posted December 1, 2012 Share Posted December 1, 2012 Chaz, would I be right in thinking that the two beams shown in your first photo are also able to move relative to each other as well as to the loco chassis? That is, would they allow the first and second axles to rock sideways relative to each other? Link to post Share on other sites More sharing options...
chaz Posted December 1, 2012 Share Posted December 1, 2012 Chaz, would I be right in thinking that the two beams shown in your first photo are also able to move relative to each other as well as to the loco chassis? That is, would they allow the first and second axles to rock sideways relative to each other? Yes Pat, quite right. The beams and the frames are drilled for a running fit on the bushes. The pivot rod is soldered to the bushes but not to the frames. This has the advantage that should I ever need to remove the beams (unlikely) I would just cut through the rod. But yes, the movement of the beams is independent - the wheel on one end of an axle can be going up whilst the other is going down. Of course this affect the axle on the other end of the beam but it all sorts itself out and the end result is that all six wheels are constantly in contact with the rail.. Chaz Link to post Share on other sites More sharing options...
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