Real locos have side control of their bogies? =8^O
Well, I sort of got in the way of it - I build and run locos too!
Damn, I threw the evidence in the rubbish bin about 25 years ago after I built a new set of frames.
Hey, I've got an old Tri-ang Hiawatha, an 0-4-0 with leading and trailing wagons to make it look like a Pacific, in a box somewhere. That would surely count as "evidence", almost a hanging offense!
Regards, Greg.P.
Why not just remove the trucks altogether and save the hastle? ;-)
As I pointed out elsewhere, the amount of vertical springing needs and should only be sufficient to keep the trucks/wheels reliably on the rails. The weight has to be there in an unsprung truck and that weight might as well be in the loco and be transfered to the truck through a suitable spring.
I'm guessing that you are running larger locos (4-8-4s etc) and the difference in rigid wheelbase to total wheelbase is much less than for a 4-4-0 or 4-6-0 and you also have plenty of current collecting wheels on the rails without concerning yourself with collecting from truck wheels. A 4-4-0 built as an 0-4-0 is going to cut a wide swathe through the outside track scenery and it is going to suffer from poor current collection with just two rigid axles collecting. Adding a sprung bogie with side control and current collection results in a much more prototypical appearance and much superior operation. I also find that continuous current collection results in much better tractive effort! (seriously)
Regards, Greg.P.
"Gregory Procter"
I think some well known American model railroader did just that.
I find I don't need any springing on the lead or trailing trucks of my steam running on handlaid code 70 track. As I wrote, I remove the factory installed "springing" and let the truck's run under their own weight, all with no derailment problems.
My largest engines are the freight (heavy) and (light) passenger and freight
4-8-2s. There's one class of 2-8-2s for freight work, one class of 2-8-0s way freight (Pick up goods) and occasional passenger service (Five engines soon be kitbashed to give me two subclasses) and a class of small 2-10-0s for light rail branch line work. None of which have springing on the leading and traiing trucks. I'm planning on two classes of 4-6-0 for freight and passenger branchline work and friends tell me they also track well without the pony truck springs.As for pick ups, all my locos with came with tender wheel pickups or have been or are in the process of having tender wheel pickups added.
Yes, 4-4-0s and, I'd imagine, 0-4-4s pose special problems. Unlike UK steam era modellers, where one really can't escape 4-4-0 and 0-4-4 wheel arangements, I don't have to worry. Smallest road power will be 2-6-0s, as soon as someone makes one that has wheels that can run on code 70 track, and my largest planned road power will be USRA or similar heavy and or light
2-10-2s for freight service. I haven't include 0-6-0s and 0-8-0s as these are just yard engines and rarely see the mainline, though mine do pick up from all wheels.-- Cheers Roger T.
Home of the Great Eastern Railway
Current IHC 2-6-0s run on my Code 70 handlaid track without problems. What size spikes are you using?
I remember reading an article from 20-30 years back. The "Sunset Line" or something like that?
OK, but derailments or no derailments isn't the entire basis for my springing trucks and bogies.
They are all "long rigid wheelbase" by my standards! :-)
Well, you obviously have enough axles for good and reliable pickup!
It's quite difficult to spring the trucks of 0-6-0s and 0-8-0s! I run from 2-4-0s with two axle tenders through to 2-12-0s with 4 axle tenders. The 2-12-0s don't present many collection or traction problems and the length of rigid frame covers the tracking problem. The 2-4-0s are more of a problem for current collection, every axle needs to collect to get 3 pickup points per side. Your 4-6-0s would benefit from the front bogie leading the loco into the curve - that's a long front overhang if you treat it as a rigid 0-6-0!
Regards, Greg.P.
"Mark Newton" wrote in message news: snipped-for-privacy@optusnet.com.au...
H0 scale locomotives are different to real locomotive Mark. The best solutions for a H0 model is different to the engineering solutions used for the prototype. I was talking about H0 scale models, not prototype locomotives in the above statement of fact.
The fact is H0 models do not need bogies to steer the locomotive. Even for the prototype the bogie on a steam locomotive does not steer the locomotive. Steam locomotives do not have active steering like an automobile. The track steers the locomotive, forcing the wheel flanges to change direction. The bogie is part of the suspension system, vertical and horizontal. If bogies were necessary to steer locomotives there would not be any successful
0-4-0's, 0-6-0's (the most successful hence numerous UK steam locomotive wheel arrangement), 0-8-0's and 0-10-0's to mention a few wheel arrangements typically with no side springing.Having operated and tested most kinds of electric H0 scale mechanisms, as well as being able to apply the theory of statics and dynamics (formal engineering qualifications) allows me to compare and comment with accuracy (metrology experience and qualifications) on what works best. I have also built my own locomotive chassis's many years ago before the advent of HO NSW outline RTR and locomotive kits. Most of these early efforts did not work that well. I made about every mistake possible in the design and construction. Lessons well learnt. The above builders were interested in the challenge of the model engineering, not optimising tractive effort or easy simple solutions. Their complex bogie solutions are not always the best for most situations, poor tractive effort is their designs weakness. Every model I have which has the springs removed from leading bogies can haul longer trains. The only advantage springs on small scale bogies is improved pickup. This is only important for some small tank locomotives. If your small tank locomotive has driven wheels sprung or compensated, then you have enough pick up, no need for the sprung bogie. All my models without sprung bogies will out pull the above builders locomotives, weight for weight, if their models have sprung bogies and have similar material wheel treads. One reason they may need more wheels for pick than I need is they probably are using mild steel wheels, Mike Sharman is guilty here, and not using light oil on the track to improve electrical conductivity. I rely on first hand information, not what is presented and misinterpreted by Mark Newton from glossy books or Magazines. Gordon Gavertt works in a larger scale, and is interested in small prototypes with small trains to pull. Their use of sprung bogies requires more work and adjustment to get a model working well, for no visual gain, and less tractive effort..
At least Greg's subjective opinion is based on operating models on an operating layout.
bogies/trucks
measurements :-)
I to have done this experiment to measure the coefficient of friction on the driving wheels of locomotives. Mark does not know how to calculate the tractive effort using this method. Also you need to have an idea of the train's rolling resistance, which requires more testing and calculations Mark does not understand. See my web page for my conclusions and how to predict train weight's and locomotive weights for various grades and curves.
On my locomotive the all the theoretical extra 50grams you suggest, which is impossible to add to most of my models would be available for extra traction all the time, 100% of it, 50grams extra, not 5grams.
The weight I use is small therefore the force is small compared to the springs many use, thus a big improvement in tractive effort results.
I run to scale speeds, typically 30 scale mph. Using narrow 2.2mm wide finescale wheels on my older track with 1.3mm flange ways Derailments can occur due to the finescale wheel dropping into the frog, then bouncing out. This is achievable on one leading turnout on my layout by running my model at about a scale 100 mph through this turnout. There are 3 solutions to this problem, run at scale speeds, use a spring on the bogie or use fully compatible wheels and track. My track is like my prototypes, rough.
If
See comments above about steering.
One can measure both stiction and rolling resistance of rolling stock.
The (theoretical) extra 5 grams would come from weight transfer. Your bogie/truck wheels need a finite amount of weight on them for reasonable track-holding. If you're not getting this weight (other than wheels, axle and bearings) by springing then you must be building that weight into the bogie or truck. I build that weight into the loco and then transfer it by way of a spring to the bogie or truck.
If your bogie/truck weight is small compares to spring force then you're imagining a much to strong spring!
That's because all your tracking weight is unsprung. If your wheel experiences (say) a 1mm drop followed by a 1mm bump back to the rail head then the force is applied to the entire truck which gains significant vertical kinetic force. My wheel, in the same circumstances and speed, only gains a much smaller kinetic force which is immediately counteracted by the weight of the loco through the spring.
I use solutions 1 and 2. My track is used by a number of different wheel standards.
I guess we will have to agree to differ regarding steering - I'm happy with my conclusions. Ditto re Mark's abilities and knowledge.
Regards, Greg.P.
One thing that doesn't change proportionately is the easier ramping effect of large diameter wheel/flange diameters. A large diameter wheel meeting an obstruction (say a frog nose or a misaligned rail joint) has a much shallower angle to lift the flange over the railhead than does a small diameter wheel. It is therefore, given equal flange depths, more likely to derail in direct proportion to the wheel diameter. For that reason, a scale 1meter diameter bogie wheel is only half as likely to derail as a scale 2 meter driving wheel. Further, a short wheelbase bogie wheel will be closer to parallel to the rail than the long rigid wheelbase driving wheel of a rigid frame loco.
True, Tri-ang managed quite nicely with large 4-6-2s that were effectively
0-4-0s with sundry details attached.Well, yes they did in every case of leading bogie locos I know of after about
1845.Sure, and that force acted first in the leading outer wheel.
There were very few express locos without leading bogies or trucks - I'd hazard a guess that there were none built in the 20th century!
You're effectively building only 0-4-0 locos in that case, with varying amounts of detail.
I'm forced to disagree there.
A loco needs at least 3 wheels, including one able to move independently of the other two, on each rail for optimum current collection.
All one needs is tractive effort in proportion to the load one would expect the loco to be able to pull.
Adequate current collection equals better tractive effort. If your loco stalls or momentarily loses current anywhere on your layout, that is the effective maximum tractive effort of the loco, even if it will pull ten times that load on the test track.
My evidence is built in the form of 4-6-0, 4-4-0 and similar locos on my layout.
Regards, Greg.P.
When you learn to distinguish between opinion and fact?
Knowing how literal-minded you are, I should not have used a potentially ambiguous term such as this. So substitute "guide" for "steer", that way even you will understand.
Every standard text on locomotive design states unequivocally that bogies guide locomotives through curves. My various editions of the "Locomotive Engineers Pocket Book" not only contain that statement of fact, they obligingly provide a formula for calculating the lateral force about the centre of gravity. Every single individual I know who has practical experience of prototype steam locomotives is aware that the leading bogie guides the locomotive into a curve.
And then, there's you. If you seriously believe that bogies do not provide a guiding force on the locomotive as it enters a curve, then you are even more ignorant than I thought possible.
As for your comment that "Steam locomotives do not have active steering like an automobile", I don't recall anyone claiming that they did. Another stupid non sequitur.
Irrelevant, since the subject is locomotives WITH leading bogies. I'll come back to this "argument" and demolish it later...
I remember a news report about ten years ago where a newly produced British train was claimed to have automatic steering amongst it's new and amazing features. (even my wife noticed that one)
In message , Gregory Procter writes
That's journalists for you. They are pig ignorant.
My suspicion is that it either had a tilting mechanisim or bogie axles that adjusted to the track radii. Even pigs could figure that trains follow railway tracks!
It's a factual statement. It is backed up by theory you clearly do not understand and experimental results which are easily reproduces in H0 scale. No bogie spring results in superior tractive effort, fact.
The fact remains the same H0 models do not need a bogie to steer or guide them, unless you are modelling a locomotive prototype which does not have flanges on the leading driving wheels.
Then the statement is incorrect, probably distorted and taken out of text by you. It should say locomotive leading bogies help guide locomotives through curves. If they provided all the guiding the driving wheels would not need flanges except on the last driving wheel. Not the case for the vast majority of successful locomotive designs. How many of the nameless individuals you know have designed a steam locomotive, if anything. That is the only relevant practical experience that counts in this case, not their coal moving or locomotive driving skills. If you understood the relevance of the formula mentioned you could repeat it here to prove your point. It does not prove your point, it simply is required to calculate how much side force you wish the bogie to take. Further analysis would reveal the leading driving wheels still have considerable side force on their flanges, thus also contributing to the guiding of the locomotive. The bogie spreads the forces over more flanges, evening out flange ware.
They do not steer the locomotive, that is what you originally claimed. It's the track and wheel flanges that guide the locomotive, the rest follows.
If you use ambiguous terms, expect clarification expert.
Totally relevant as the subject is H0 scale locomotives. It absolutely proves bogies are unnecessary for steering or guiding locomotives, in the real world and for models. We will be waiting a long time, because you either need to produce the sums or results that show springs on bogies increase tractive effort.
I've already demonstrated a sum that shows that for equal downward force on a weighted bogie or sprung bogie, (ie equal traction on level track) the sprung bogie locomotive will have more weight on the drivers on an upward gradient where more traction is required.
Regards, Greg.P.
(the usual blather, snipped)
When it comes to ambiguous statements, obfuscation, distortion, taking things out of context, and outright lies, I'll always defer to your undoubted expertise.
I've never yet seen you argue any position on any subject without resorting to any and all of the above, plus whatever other primary-school debating tricks you think necessary.
So I'll concede this round, knowing as I do how vitally important it is for you to have the last word.
All threads where Flynn is a participant eventually turn into slanging matches. See his web page for details!
No, thanks.
The weight shift you referred to is minimal. Here are the relevant sums that impact on tractive effort. I decided to measure rolling resistance using the incline method on a H0 bogie. The bogie's mass was about 10g. Its rolling coefficient is about 4.25 times higher than the rolling resistance of pin point bearings. Thus a 10g locomotive bogie results in a decrease in train mass of 10g x 4.25 = 42.5g. One 4 wheel wagon. If we use a spring so the axle weight is proportional to the prototype we get the following result. Assume a 4-6-0 with a mass of 400g. With your spring loaded bogie we get
300g on the driving wheels and 100g on the bogie. 100g x 4.25 = 425g less train mass that can be pulled. That's about 4 bogie wagons. 300g on the driving wheels means the model can pull 3kg of train on the flat without a bogie (using my table on my web page). The bogie bearing friction alone in the bogie reduces the train mass by 14% Consider a straight1 in 50 grade. The load the 300g locomotive can pull up a straight grade of 1 in 50 without a sprung bogie is 300g x 4.9 = 1.47kg (from the table on my web page). Now we have a decrease in train mass of 29%. Consider a grade of 1 in 20. The load a 300g locomotive without a bogie can pull up a straight 1 in 20 grade is 300g x 2.7 = 810g. (from web page table). Now using the sprung bogie we get a loss in train mass of 52%. If I use a 4-4-0 as an example the results will be worse. You need to increase the weight more than 52 % to match the tractive effort of a lighter model using no sprung bogie and maintain the prototype axle load proportion purely because of bogie bearing friction. An extra 150g simply won't fit. Also the comparison above assumes the model with no sprung bogie is only 300g total mass. Make the total mass the same for both options and the difference is larger again, more than 50% on the flat. It is clear for H0 scale models using sprung bogies to simulate scaled down prototype axle loads results in under scale train lengths.
That's _extremely_ light!
Do your bogie wheels not rotate???
Rewind a little: Your 4-6-0 cannot have it's smokebox and boiler overhang filled with lead because that weight will unbalance your loco so that over 50% of the weight will be on the front driver. If you have a motor over the rear driver then even less weight can be added. My 4-6-0 can have your 300g plus an additional 100g in the smokebox, supported by the 10g sprung bogie. I don't believe you can operate a loco with an unsprung bogie of 10grams weight. I also don't accept that the friction of the bearings increases at a rate directly proportionate to the weight carried by it. For one thing, your 10 gram bogie does not have1/10th of the bearing area that my 100 gram bogie has. On a 1:50 my 4-6-0 gains an additional 2 grams shifted to the drivers.
Of course it will, I have all that previously unused boiler and smokebox space, as well as utilizing the weight of the front half of the whitemetal boiler/smokebox which is, on your 4-4-0, lifting the rear drivers off the rails
I believe in adding as much weight as is possible! With both the 4-6-0 and more so with the 4-4-0 the inherent unbalanced weight is utilized.
None of us can run scale train lengths. The friction of model bearings doesn't scale, so where a light weight 0-6-0t (30 tonne) loco will easily move a 1000 tonne train in a level yard, a model 0-6-0t won't even budge a 60 wagon rake. I can weight my locos so that they will operate with a train that _represents_ a suitable prototype train without difficulty.
OK, I'm off to weigh some bogies. :-)
Regards, Greg.P.
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