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nswgr1855

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  1. Hello Nick, I have done the experiments in H0 a couple of years ago so my layout grades would not be to steep for the trains I wanted to run. My results will be relevant to 00. I tackled the problem from a slightly different perspective. Firstly I made the assumption all wagon weights were proportional to their length. I use the Australian Model Railway Association Mass standard http://amra.asn.au/standards/ I measured what I call the coefficient of rolling resistance of my wagons by using the inclined track method, that is inclining a piece of track with a wagon on it and measuring the incline when the wagon starts to roll. There is a large difference measured between different wagons. I only use pin point axles and bearings which are usually free rolling. The value I picked was the largest typical value of 0.02. Like you I measured the coefficient of friction of my locomotives using an inclined plain. I wanted the worst case so for calculation purposes I used the lowest value, 0.2 which was on track with a small amount of oil, which I use for improving electrical contact. From these values you can calculate easily the maximum train mass that can be pulled on flat straight track by a given locomotive mass which works out at train mass =10 times locomotive mass. Experiments confirmed this. Measuring curve friction is more difficult and to confirm by experimentation. Over may years I have tried to do the experiments on different layouts with Helices. The problem is the radius, grades, locomotive and wagon variables are hard to control. Any way I came up with a rough rule of thumb for layout design to compensate for the curves on grades, and that is multiply the prototype grade by 1.75,(1:40 becomes 1:70) If you want to run prototype length trains up to 2700mm long on typical H0 model railways using curves down to 900mm radius. Conversely going the other way, a 1:40 grade on your layout is like having a 1:23 prototype grade. DCC will make no difference to pulling power other than if it can control the motor better at low speeds. What will make a difference is wheel tire material. Generally harder materials used for model railway wheels have a lower coefficient of friction but are preferably used due to lower electrical contact resistance and less dirt pickup. Also what makes a big difference is if all the loco weight is on the driving wheels. If you have non powered bogies with inside plain bearings, that is the formula for a poor pulling model. These models tend to have traction tires in order to pull enough. Cheers, Terry Flynn.
  2. I know many here will not be much need for the use of an air compressor sound on your model UK steam locomotives, but I will ask the following any way. How do I get to make the air compressor noise to automatically start when my locomotive comes to a stop. Is it something to do with CV 158? Thanks for any help, Cheers, Terry Flynn.
  3. Be careful exactly scaling down track centers. The smaller the scale the more over scale the end pay on our wheel axles. The error is amplified with the overhang of 4-4-0 locomotives, probably the worst offenders. Cheers, Terry Flynn.
  4. I don't understand why you want to use A5 turnouts If you want to run 0-6-0 locomotives through them. If you build an A5.25 turnout instead, it is only a few mm longer and gauge widening then is not needed. Keeping the gauge tight means less side motion at the end of models, making it look better, minimizing buffer lock. If you are making a crossover, then you have in practice close to a reverse curve. For reverse curves I would increase the turnout minimum radius by 20%. In this case an A5.5 is big enough. The crossover (2 turnouts) works out only about 7mm longer. Cheers, Terry Flynn.
  5. No, the AMRA standard says 5 times the vehicle length. So what is your radius and six coupled locomotive length? I have no trouble getting my 1/76 scale GWR 0-6-0 (124mm 0ver buffers) through 00-SF turnouts, no gauge widening with a minimum radius of 610mm (24"). This is just under the AMRA standards recommended minimum. The AMRA calculation is 124mm x 5 = 620mm. I have removed most of the side play on the outer axles, but left the end play on the centre axle as delivered from Bachman. This radius is still much sharper than your prototype examples, so I am not being unreasonable. Wheel diameter is not a factor if the front flange angle is not to steep. Also the bigger the driving wheel the longer the locomotive will generally be, naturally compensating by producing a larger minimum radius using the formula from the standard. Cheers, Terry Flynn.
  6. Nice video. The 4 way turnout is a beauty. The AMRA minimum radius standard suggests you can go as tight as 3 times the locomotive length being an 0-4-0. For example, using my 1/76 scale Hornby Pug as an equivalent locomotive, it is 85mm long. This means it can get around 85mm x 3 = 255mm (10") radius curves. Cheers, Terry Flynn.
  7. It's expected if you are using curves with a radius sharper than 5 times the length of your six coupled locomotives. The extra sharp curves are really only appropriate for a 0-4-0 if you want your models to look realistic. Sounds like you are in toy train set territory.
  8. The theory works for all scales and any 3 point gauge less than the rigid wheel base of any six or more coupled locomotive will not compensate enough. In practice most models built in small scales have over scale end play, thus negating the need for gauge widening in small scales. Also most standards used have a track gauge already with gauge widening built in. The exceptions are the close as possible standards like scale 7. Cheers, Terry Flynn.
  9. Clearly you have not done the maths. Basically to gain suitable gauge widening for a 0-6-0 locomotive with no end play your 3 point gauge needs to be as long as your locomotive wheelbase. I do not know of any 00-SF 3 point gauges that are 70mm long to suit a GWR pannier tank loco. If you need to gauge widen to get a model around a curve, you are using curves to sharp for the length of model. Cheers, Terry Flynn.
  10. Well done Gordon, Strange thing, using my "in tolerance" metal roller gauges, I get the same result. My speed tests are as follows. My fastest Steam locomotive is a Hornby LNER P2, 2-8-2 with a Hattons DCC decoder fitted. Maximum scale 00 speed through complex track work on a H0 12 chain scale curve was 86 00 scale mph, light engine forward and reverse. My layout speed record holder is a DCC fitted Lima/Joef 8 car H0 scale TGV with no coning on the wheels, cookie cutter flanges. Maximum scale speed through my complex track work was 224 H0 scale Km/h (140mph). I do not dare to do these speeds on the recycled RTR turnouts made in Japan from 30 years ago in my fiddle yard. The "normal" maximum speed for the locations I am modeling is about 60km/h (37mph). Cheers, Terry Flynn.
  11. On wheels going around a curve, if the tyres are flat, then the inner one journeys a shorter distance than the outer, one must slip. In real life on the railway the curves are gentle and elastic effects in the rail compensate and slip does not occur that much, but can set off screeching noise from the tyres, In theory coned wheels and inclined track top overcomes the problem, if the track is correct and the wheel unworn and to perfect standard profile.. With models though you are in the hands of the gods as to what taper is there or whether the top of the rail is inclined (as in DCC). The self steering and the diameter difference on the wheel are swamped by other factors, like the slack in bearings allowing the axle to run out of true etc., etc., All these little points add up to explaining why some makers just get "bad" points, constant jittery running, stalls, and unneeded roll etc., Mind you, if you want such track and the look of an old industrial track.............. I have no trouble running wheels with no tread taper on my H0 track. If you get "bad points" it's about the dimensions of the turnout not being compatible with the wheels on the models, in other words, the turnout is out of tolerance. Cheers, Terry Flynn.
  12. A typical 3 point gauge makes minimal difference to the track gauge. They are not long enough. My experience is you do not need to gauge widen because most small scale models have over scale axle end play. To determine the practical minimum radius have a look at the AMRA minimum radius standard http://amra.asn.au/standards/ Cheers, Terry Flynn
  13. Clearly you have ignored the details of my posts. My way to build my H0 turnouts is the long proven conventional way of using roller gauges and track soldered to PCB sleepers. I use RTR flex track whick has a broader tollerance on my general trackwork than most posting hear use as US H0 RTR flex track gauge can be as wide as 16.8mm. The precission in track building gauges is warranted if you want smooth reliable running. These days I am able to push or pull trains made up of rakes of more than 30 RTR 4 wheel wagons at scale running speeds through complex trackwork. Cheers, Terry Flynn.
  14. A wheelset on a curve follows a reasonably radial path from the centre of the circle, and should behave as if on straight track (dismiss the fact that one wheel is constantly slipping on curves), but such a wheelset is only found on single axle trailing or leading wheel. Most wheels are constrained by the frame to travel along a curve at an angle to the true radial line, and two effects occur, the flange becomes effectively thicker and the tyre effectively narrower on curves. Also the root curve between the tyre and flange becomes less effective.(it is "shaded" by the flange). On small crossing point angles, (large radius) the effect of this is too small to bother about, but it does affect the design of a tighter point, as the wheel is not running in the way a plain cross section would show. The effective back to back tightens up, the flange becomes wider, the tyre smaller, and this combination causes the wheel to not be restrained by the check rail and the wheel drops because the tyre edge cannot reach both the end of the switch rail and the tip of the crossing, This whole reasoning was brought up by Mr Pritchard in explaining the flangeway and check rail clearances on streamline 100 points, the effect is worst with wheels like the Dublo profile, and he had to build the point to take these.as well as more scale wheels. Also the other forgotten problem with wheels in the argument above is that the effect varies with wheel diameter, ever not noticed that diesels sail through complex point work, whereas a steam loco will rough ride, despite having perfectly good wheels set to correct back to back?? It also helps explain why 16.2 works..........helps keep the "effective" flange width in the correct path through the point. These effects are slight, but measurable, and no, I have not sat down and worked the geometry out to the nth fraction of a degree or part of a thou... but it is there and usually never even considered in making points.....except that the NMRA standards did include such a study and may help explain the better running than 00 on the same track. The whole issue vanishes on P4, the points are too large to show the problem, and all the wheels match each other bar diameter. Neither does it bother ordinary 00 much, the tolerances of the commercial stuff cover it up, but it does affect better made scale track built to tighter standards, and may explain some jittery running on well made points with good wheels, you get an accumulation of tiny errors and end up with wheel drop. Perhaps an answer is that each particular radius or length should have the flangeway and check rail set for that radius, one size may not suit all points. The simple answer is to use is the AMRA minimum radius standard http://amra.asn.au/2010/05/22/standards/. Then finescale standards work for all cases. Cheers, Terry Flynn.
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