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Post by Deleted on Dec 14, 2018 17:53:44 GMT
gs or wheel profile. - DY has shown a parallel wheel tread, no coning, and I can't see mention of coning in the text. Really??.. you astound me sir...you learn something new every day.. I still find it hard to believe even though you're said it...no idea why he did this but it isn't in his design that I'm building.. Regards Pete
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Neale
Part of the e-furniture
5" Black 5 just started
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Post by Neale on Dec 14, 2018 18:47:33 GMT
Well, I'm not sure if I've learned anything or not, except to expect the unexpected! I have the DY drawings, as supplied by Reeves and now conveniently scanned to pdf for easy computer viewing, plus a scanned pdf version of the original LLAS articles which were kindly loaned to me by a fellow club member. I've had a second look at both, and tender, bogie, and D&C wheel drawings and accompanying text make no reference to coning. I'm assuming that this is different to your FS? I'm happy to be corrected (and my tender wheels are now coned come what may, as per GL5 profile) but that's the way I read it. So, should one just follow DY's design and "it'll be fine", parallel treads or not?
I still have a fairly full set of LLAS sitting in the office next to me. When I get a chance, I'll have a quick skim to see what DY does for some of his other designs of a similar style.
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Post by Deleted on Dec 14, 2018 19:05:18 GMT
Curiosity got the better of me and I just took a look at Doncaster's wheel profile... you're right, they show parallel? ... this is beyond my comprehension... how can he make such an accurate model with the wrong wheel profiles?. I can only assume that back when he did model designs this was the norm within model engineering, perhaps before GL5 with their attention to detail and search for true miniatures put folks right? the crazy thing is, as I'm typing this my poor memory is beginning to recall a discussion on this in the past Pete
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pault
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Post by pault on Dec 14, 2018 19:30:06 GMT
Let's not forget that certainly in larger sizes gauge widening on curves is a normal practice where required
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pault
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Post by pault on Dec 14, 2018 19:33:32 GMT
Certainly many of the early designs right up to probably the 80s or 90s had parallel treads
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Post by Deleted on Dec 14, 2018 19:48:58 GMT
Certainly many of the early designs right up to probably the 80s or 90s had parallel treads Thank's Paul... things are beginning to add up... Pete
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Neale
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5" Black 5 just started
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Post by Neale on Dec 14, 2018 20:47:06 GMT
...and did they have more flange wear, more derailments, more rolling resistance, as a result? Is the modern trend to "proper" coned wheels and more scale wheel profiles due to wanting models to better resemble their prototypes or because they work better?
I have no information one way or the other, but I'm curious!
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Post by RGR 60130 on Dec 14, 2018 21:24:33 GMT
Certainly many of the early designs right up to probably the 80s or 90s had parallel treads I seem to remember LBSC explaining why he favoured parallel treads but I can't remember why! I'm sure someone will remember or be able to find it. Reg
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don9f
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Les Warnett 9F, Martin Evans “Jinty”, a part built “Austin 7” and now a part built Springbok B1.
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Post by don9f on Dec 14, 2018 21:31:36 GMT
Hi, a most interesting thread and I agree with everything that’s been said.....BUT just to give my own experience:-
When I ran my 5” 9F back in the 80’s & 90’s it was mostly on ground level track (my knees weren’t shot back then) and I sat on a seat that could be temporarily fitted to the back of the tender. Our track at the time was “black” steel bar and probably had inadequate super elevation for it’s (from memory) 50 foot radius curves. The loco ran a considerable mileage in those days but unfortunately became “stored out of use” in 1996 and is currently under overhaul.
The point is that during this recent work, I discovered that one of the tender wheels had come loose on its axle! The loctite had failed but due to the tender design, the wheel couldn’t come off, it must have just run free on the axle for an unknown length of time.
There is no proof whatsoever that this is related to the subject under discussion but with me sitting on the tender, the axle loading was obviously way out of proportion to how the loco would be otherwise....like on raised track where these days I will only be sitting on a vehicle behind.
Thanks for reading!
Cheers Don
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Post by dhamblin on Dec 14, 2018 22:04:37 GMT
The point is that during this recent work, I discovered that one of the tender wheels had come loose on its axle! The loctite had failed but due to the tender design, the wheel couldn’t come off, it must have just run free on the axle for an unknown length of time. That's interesting as Grandad's Britannia also has a single loose wheel, in this case on the rear axle, right hand side. Most likely press fit so it was probably the largest tolerance of the set. Parallel tread and mostly run on steel bar raised track. Regards, Dan
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Post by ettingtonliam on Dec 14, 2018 23:02:13 GMT
The point is that during this recent work, I discovered that one of the tender wheels had come loose on its axle! The loctite had failed but due to the tender design, the wheel couldn’t come off, it must have just run free on the axle for an unknown length of time. That's interesting as Grandad's Britannia also has a single loose wheel, in this case on the rear axle, right hand side. Most likely press fit so it was probably the largest tolerance of the set. Parallel tread and mostly run on steel bar raised track. Regards, Dan A moved wheel on a Britannia? Just like the real thing, then!
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don9f
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Les Warnett 9F, Martin Evans “Jinty”, a part built “Austin 7” and now a part built Springbok B1.
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Post by don9f on Dec 14, 2018 23:13:44 GMT
I took my part-complete 5" Black 5 tender along to my local club night earlier. One piece of advice I was given was to leave one of the tender wheels to be a running fit on its axle and only lock one in place. The reason given was that curves on typical model tracks have much tighter bends than you would find if you scaled down full-size tracks and coning (if there is any) is not enough to avoid one of the wheels slipping. Hi, officially a 9F could negotiate a curve as tight as 4 1/2 chains “Dead Slow”....that is 99 yards radius. If there wasn’t any gauge widening already, there probably was afterwards! If my sums are correct, that equates to just under 27 feet radius in 5” gauge. The restriction would be for the engine, the tender could probably go tighter still but models don’t necessarily behave the same as full size and in my own case, the limiting factor wasn’t any problem with the main drivers, it was lack of enough side movement of the pony truck on curves less than 30 foot radius. When built, my model had a 2 degree coning angle on all treads and whereas the engine wheels were ok when I checked recently, I found that the tender wheels all had thin flanges and had to be re-profiled....further indication of the problem I was unwittingly causing by sitting on it! Cheers Don
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Post by delaplume on Dec 15, 2018 0:18:21 GMT
Hi Don, For those not aware}--- the 9F has a flangeless 3rd wheel set ( and a 3-way profile ) combined with extra side clearance which helps it achieve this..... Is the model the same ??
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Gary L
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Post by Gary L on Dec 15, 2018 0:41:02 GMT
I took my part-complete 5" Black 5 tender along to my local club night earlier. One piece of advice I was given was to leave one of the tender wheels to be a running fit on its axle and only lock one in place. The reason given was that curves on typical model tracks have much tighter bends than you would find if you scaled down full-size tracks and coning (if there is any) is not enough to avoid one of the wheels slipping. Hi, officially a 9F could negotiate a curve as tight as 4 1/2 chains “Dead Slow”....that is 99 yards radius. If there wasn’t any gauge widening already, there probably was afterwards! If my sums are correct, that equates to just under 27 feet radius in 5” gauge. The restriction would be for the engine, the tender could probably go tighter still but models don’t necessarily behave the same as full size and in my own case, the limiting factor wasn’t any problem with the main drivers, it was lack of enough side movement of the pony truck on curves less than 30 foot radius. When built, my model had a 2 degree coning angle on all treads and whereas the engine wheels were ok when I checked recently, I found that the tender wheels all had thin flanges and had to be re-profiled....further indication of the problem I was unwittingly causing by sitting on it! Cheers Don The logic of this, is that for tracks with tight curves, the coning angle should increase, and definitely not decrease to nothing as in parallel treads. I mentioned David Hudson earlier, and at Bristol we use self-steering bogies derived from his 5" designs on all our 7¼" passenger cars. They are highly satisfactory and run with a very low rolling resistance, the object of the design. Part of the system is a special profile for the wheel tyres, which starts at 3 degrees and rises to around 12 degrees where it meets the quite large flange root radius. These are derived from (but not identical to) the compound tyre profiles developed at Doncaster in the later years of BR. These large compound angles do not on their own make the bogies 'self steering' (a common misunderstanding) but they do prove that larger cone angles are perfectly satisfactory in service on miniature tracks, even without a matching inclination of the railheads. WRT the 9F, it is widely known that in full size the centre coupled wheels were flangeless, because of the gauging issue. On the GWR it was standard for the flanges of the middle drivers to be thinned (sorry, I don't have the dimension) for the same reason, though this is hardly ever specified in miniatures which arguably need it more. On GWR 2-8-0s and the 2-8-2Ts both middle coupled axles had thin-flanged wheels, and on 4-4-0s the front coupled wheels were so treated. I can't speak for other lines. I seem to recall that the intermediate coupled wheels of the 9Fs had thinned flanges too, doubtless someone more knowledgeable can confirm. HTH Gary
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Post by ettingtonliam on Dec 15, 2018 0:42:14 GMT
Certainly many of the early designs right up to probably the 80s or 90s had parallel treads Henry Greenly writing in 1922 specified coning the treads at 1 in 20, although in his Locomotion design in 1928, it was 1 in 25. Having had a look through a selection of MEs from the 1950s and 70s, covering LBSCs Brittania, Don's Jersey Lily and Mountaineer and Martin Evans Torquay Manor, none of them mention coning or show it on their drawings, though they all, Martin Evans in particular, are apt to dismiss wheel machining as something thats been covered many times before, and doesn't need detailing again. By 1998, David Piddington at least, showed coning on Locomotion's wheels.
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Post by delaplume on Dec 15, 2018 0:59:34 GMT
The problem with coning your model wheels is that the club track that you are running on must also have inclined rails to match your coning......
If not then you have a parallel tread sitting on an angled rail which gives you a line contact---- ie no power transmission at all..( or braking for that matter !! ).
How many club tracks use rectangular section steel bar for rail--- held vertically ??.........
.or more up to date}-- use Vignoles section Aluminium rail held vertically ??
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Post by delaplume on Dec 15, 2018 1:02:04 GMT
Hi Gary,
Isn't there a spherical joint on the GWR 8-coupled locos ?? ( second axle )..
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Post by racinjason on Dec 15, 2018 5:31:07 GMT
The problem with coning your model wheels is that the club track that you are running on must also have inclined rails to match your coning...... If not then you have a parallel tread sitting on an angled rail which gives you a line contact---- ie no power transmission at all..( or braking for that matter !! ). How many club tracks use rectangular section steel bar for rail--- held vertically ??......... .or more up to date}-- use Vignoles section Aluminium rail held vertically ?? If you look at the end of black flat bat it's not square on the short side thet the wheels run on so the tapered wheel works better than a parallel wheel. Jason
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don9f
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Post by don9f on Dec 15, 2018 9:23:20 GMT
Replying to a couple of points....
Yes Alan, the Les Warnett 9F model has flangeless middle wheels but he specified that the profile is the same 2 degree coning angle, just that the flange isn’t there. In reality in later years, the 9F’s had a “Special X” profile developed for them that wasn’t coned in that way at all but had a number of different angles applied symmetrically across the tyre.....also these middle wheel tyres were slightly wider than the other wheels, but not on my model. I only found out about all this after I had built it.
Secondly, yes Gary the real intermediate 9F drivers have “Thin” flanges, which are 1/8” (3mm) less than the leading & trailing wheels, the change being to the “working” side of the flange. This feature is not repeated on my model.
Cheers Don
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don9f
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Les Warnett 9F, Martin Evans “Jinty”, a part built “Austin 7” and now a part built Springbok B1.
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Post by don9f on Dec 15, 2018 9:45:26 GMT
Hi back to the subject raised by Neale, an added problem I discovered during the work I did on my tender just over a year ago was that if all relevant dimensions were to drawing, there was no lateral side play in any of the tender axles. This cannot be right in my opinion and obviously went unnoticed during its building. Whether it contributed to one of the wheels coming loose is unknown....but it can’t have helped! I have since modified things so there is now approx 1/16” side play for each axle. This was done by machining a small amount off each wheel boss.
On this design and probably the same on other tenders, the axleboxes are only restrained in their guides by flanges on the inside.....so the boxes can accommodate the newly created lateral movement. I posted about this and the modifications I did in my thread during Nov 2017.
Cheers Don
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