Re: EM gauge wheelsets..Ian Rice book

> "Terry Flynn" wrote

> > > > > Nickel silver might be slippery, but mild steel has some big > disadvantages > > > for small scale models, one is poor electrical conductivity after it > > rusts, > > > another is steel wheels are no good if you want to use magnetically > > operated > > > uncoupling. Rusty steel wheels on rusty track also have a high rolling > > > resistance. > > > > Rust? The simple answer there is not to let the track or wheels get > rusty, > > surely! I don't run models in a garage, a shed, or outdoors though, and I > > would wholeheartedly agree that steel rails may not be the best option > > there. > > > > > If your models cannot pull prototypical loads, don't blame slippery > nickel > > > silver or stainless steel, look elsewhere. I can run longer than scale > > > trains using these materials in H0, so there is no reason why others > can't > > > do it in H0 or 00. > > > > I actually model in EM gauge, and I have models with nickel-silver wheels > > that will pull a house down running on nickel-silver track. These are > > kit-built, with chassis built following the best parts of Iain Rice's and > > Mike Sharman's philosophies. I personally find problems when converting > RTR > > stock, because the chassis designs usually make an 0-6-0 really an 0-3-0 > as > > far as wheels in contact with track are concerned. One real failure of > mine > > was converting the Hornby Dean Goods tender drive mechanism to EM using NS > > wheels, and now it can't pull the skin off a rice pudding. Steel wouldn't > > have been any better in that case, and the whole thing has been put back > > into it's box pending a re-think. > > > Tender drives should be avoided if traction is important. The tender drive > is pushing locomotive with bearings which have a high rolling > resistance compared to pin point bearings. Using small ball bearings instead > of inside plain bearings should improve things, however a more conventional > locomotive drive is preferable..

Where do you get ball bearings suited to 2mm axles???

> > > Ironically, surrounding me whilst typing this is a Hornby Pacer with > > Branchlines conversion, a GWR 48xx (shown on my website) and a Pannier in > > build - the latter two with proper chassis - and two out of three have > > nickel-silver wheels! > > > > Your web site shows some lovely models. Your spinner probably does just > that. > I have noticed inside bearings and some of the load on your models are on > non driving wheels. I try to avoid this, your single is the exception to > this preference for obvious reasons. For example my 4-6-0 is actually built > as an 0-6-0 with a 4 > wheel bogie floating along in front, doing nothing except looking like it is > doing something.

Ewwww! Make the bogie earn it's keep! For a start it should be collecting current, so it needs some weight. If it has weight then it might as well be sprung. If you've gone to all that effort then it might as well be guiding the loco, which will cause the entire loco to act more like the prototype does/did rather than an extended 0-6-0 with a small wagon trapped underneath.

This way the friction force of the inside bearings on the > leading bogie is minimised.

By the time you get to a 4-6-0 the loco is big enough in HO to get more lead inside than the motor can handle!

Never use inside bearings on tenders unless the > prototype had these, then use ball bearings. Using these rules maximises > tractive effort for our models without the need of all lead body > construction. > > > Anyway, I just prefer steel, and it's my train-set :-) > > > > Can't argue about that. > > > -- > > Paul Boyd > >
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Reply to
Gregory Procter
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Hi Keith

Doh! I've just been playing with a bit of Biro tube, and it seems OK if the gap is kept small. I didn't use any Araldite in my experiments, but I guess that would stiffen it further. Even so, it would take a lot of weight to bend an axle made this way. The Plastruct range doesn't seem to have a suitable tube available. The sizes are imperial, and the nearest is TB-4 which gives a 2.2mm inner. The next one down is 1.6mm inside dia. Next problem is compensation - but I have some ideas there. Most tender frames have a flippin' great hole where a beam pivot would normally go, but who says the beam has to be straight? Perhaps springs would be better.

I did. Wonderful locos. I visited SA a couple of times as a kid, and I'm sure I saw a Garrett whilst on a drive from Jo'burg to Durban. At least, my Dad told me that's what it was! September 11th/12th on the Welsh Highland Railway is "Superpower Weekend" where double-headed NGG16 Garretts will be running. Unfortunately I have to come back from there on the 10th!

PS - now signed up to MERG groups - thanks.

Reply to
Paul Boyd

That's more than 25% or 15% less tractive effort on flat track due to the high friction force of inside bearings. Add a change in grade and at the dip in track the front bogie takes more weight, decreasing tractive effort again.

Reply to
Terry Flynn

Try fitting equalization! But seriously: The front bogie of a 4-6-0 can carry the extra weight that will fit inside the smoke box so there should be very little weight transfered from the drivers at the beginning of a gradient and a fraction extra added as the loco climbs the gradient. If the decrease in tractive effort just as the loco enters the gradient has any effect then the loco and train are not going to make it up the hill!

Ball point pen inners should do the job.

Regards, Greg.P.

Reply to
Gregory Procter

Although you can have a heavier model overall if you use a spring taking the extra weight at the front of the locomotive, all this extra weight does besides increasing wear is to increase the rolling resistance in the front bogie, decreasing overall tractive effort of the model. Dips in the track happen all over the track, not just at the start of the hill, but your point is valid.

Reply to
Terry Flynn

Less mass also means poorer current collection and poorer running.

Check that your coupling rods aren't being used as a traction current path - if you have one wheel wiper that works better that the others then current might be passing from one wheel through the side rod bearings to the other wheel with resultant pitting and faster wear!

My assumption is spot on. If the bogie is carrying the correct amount of weight then the driving axles will be carrying equal weights. In fact, is shouldn't matter if one driving axle carries more than it's share of the total tractive weight because the total will be the same. The prototype balanced the weight over multiple axles because of the limited weight carrying capacity of the permanent way. If all the weight falls on only two, or even one, driving wheel it should make no real difference on the model.

Reply to
Gregory Procter

Unless you use a motor that has only just enough torque to move your model, some extra weight should not reduce the tractive effort of your model! Today's motors have more torque than we actually need, which allows use to weight them to just below stalling weight.

I'll lend you a big hammer! ;-)

The suspension on your bogie or truck should have sufficient movement to allow the locomotive to traverse the size of vertical deflection your permanent way staff build in to your track. In all likelyhood this will be somewhat greater than the prototype, so the spring rate needs to be softer than the prototype's. In case I haven't explained what I mean, I'll put it a different way: Say the prototype scaled allowed 0.5mm of vertical travel and the weight borne by the bogie springs went from 10 tonnes to 15 tonnes but your model needs 2.0mm of travel. You can, by varying the length of any given spring change the weight taken at different deflections. ie if level and the bogie is carrying 100grams, then at 2mm deflection you can adjust the loading to any number between 101 grams and half the weight of the loco. If you want (as I do) to use the bogie to guide the loco into curves in a realistic manner then a weight in similar proportions to the prototype's weight distribution works out quite well.

Regards, Greg.P.

Reply to
Gregory Procter

Only if you do not use light oil to improve wheel track electrical conductivity.

The excess wear was also due to thin side rods.

The correct amount of weight for the front bogie to carry for maximum traction on small scale models is no weight.

That's right, and that's what I was inferring when talking about having different amounts of weight on the driving wheels. What makes a difference is the extra friction on the bogie bearings and less weight on the driving wheels that is the result of sharing weight on locomotive bogies.

Reply to
Terry Flynn

snip

It depends on where the extra mass is put. If it is above a bogie which is taking the extra weight, then your tractive effort will be less compared to a model with the same weight on the driving wheels, and none on the bogie. All my examples assume the motor has excess torque to do the job.

I agree. The best spring rate for traction is 0 N/mm.

On our small scale models it is unnecessary to use the leading bogie to guide our models. There is no visual observable advantage, flange wear is not a problem. My H0 scale crew don't complain about the locomotives ride.

Reply to
Terry Flynn

I have very definite ideas on track cleaning and oiling! NO abrasives - continual cleaning by way of track wiping wagons - a film of light oil on railheads to stop oxidation.

Yeah, thin side rods and current flow will cause excessive wear!

We have to agree to disagree on that point - my bogies earn their keep, both in guiding the loco and in current collection.

I don't consider that to be significant because we don't have strict axle load limits on our models and in almost every case the motors we use have more power than we need. Add more weight over the driving axles to compensate!

Regards, Greg.P.

Reply to
Gregory Procter

If two locos have equal weight over the driving wheels then the tractive effort is going to be much the same. I work on a carrying axle bearing half the weight of a driving axle. Point a 4-6-0 uphill and a portion of the extra bogie borne weight will transfer to the driving wheels.

Traction isn't the only factor to consider!

For example take that horrible Tri-ang Hornby 0-4-4T (I forget the class) which was built as an 0-4-0 with a loose trailing bogie. Running forward, it took up a reasonable attitude to the track on curves with the rear driven axle attempting to align with the curve radius line which left the rear buffer beam a fair way out of alignment with the following vehicle. Running bunker first, the driving wheels again tried to align themselves with the leading driving axle following the outer rail and the rear (front) axle attempting to align itself with the curve radius line. The result was the bunker buffer beam cutting a swathe through the fence/hedge/neighbouring countryside. A gentle push sideways would cause it to loosely swing about an inch in to the centre of the curve! Side control of bogies is needed!

I can observe the difference in loco attitude! I have tested my theory by building locos with side control and running them both with and without - I'm convinced!

Regards, Greg.P.

Reply to
Gregory Procter

Gregory Procter wrote: >

Greg, surely you must realise by now that Flynn cannot abide anyone who dares to disagree with him. To do so is to invite an ongoing denunciation of your character, motives, experience and skills.

Reply to
Mark Newton

Gregory Procter wrote: >

Poor old Flynn would be incapable of making any such observation. He has demonstrated on a number of occasions that he is as blind as a bat!

Reply to
Mark Newton

I thought I was doing rather well. ;-)

It's ok, I have none of those!

I still can't abide 10 or 12 wheel 0-4-0s!!!

Regards, Greg.P.

Reply to
Gregory Procter

Awww come-on, where would the hobby be without a few Flynns?

Reply to
Gregory Procter

Yeah, so far you are. Give him time... :-)

Oh, ok!

Nor can I. Locos without some side control on the bogies/trucks look awful when entering curves, particularly if your layout is near eye-level, and you've gone to the trouble of providing easements and superelevation.

BTW, the TriAng loco you mentioned earlier was an M7. Lovely engine, shocker of a model!

Reply to
Mark Newton

LOL!!!

Yeah, it certainly would be a little duller without our resident crackpot!

Reply to
Mark Newton

So go back to trainset level - put a GWR King or SR Schools on set-track on the carpet and watch them go from straight to curve and back - a bottle of whiskey may be needed for sensitive souls! :-(

That's the one! Almost worth owning one to demonstrate how bad models can be!

Reply to
Gregory Procter

The expert hypocrite comments. Mark Newtons character is clearly defined by the disgusting and foul language he has used in model railway news groups. Mark's experience is always exaggerated, claiming experience and qualifications he does not have.

Reply to
Terry Flynn

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