Rigid Chassis Locos?

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Guy Rixon
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Re: Rigid Chassis Locos?

Postby Guy Rixon » Sat Mar 21, 2020 8:59 am

Concerning springing to improve electrical contact, it's worth noting that this is now common practice in 2FS, where spring for track holding don't work much and aren't considered necessary.

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Le Corbusier
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Re: Rigid Chassis Locos?

Postby Le Corbusier » Sat Mar 21, 2020 9:14 am

Guy Rixon wrote:Concerning springing to improve electrical contact, it's worth noting that this is now common practice in 2FS, where spring for track holding don't work much and aren't considered necessary.

From my perspective it is self evidently true that many have experienced issues over the years with electrical contact and developed compensation and springing methods to solve this issue (alongside other issues such as track holding). It is also self evidently true that both methods are successful in delivering improved electrical contact. It is just odd that in both 00 and EM, where track holding is deemed to be less of an issue, there are some extremely prominent kit and scratch builders who build totally rigid chassis which are noted for reliability of running .... its a mystery :?
Last edited by Le Corbusier on Sat Mar 21, 2020 9:29 am, edited 1 time in total.
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billbedford
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Re: Rigid Chassis Locos?

Postby billbedford » Sat Mar 21, 2020 9:22 am

Enigma wrote:The late Roy Jackson wasn't a believer in 'flexible' chassis either and his locos ran on 'Retford' faultlessly. I remember him saying that he did try compensation at least once, possibly more, but he wasn't convinced by it.

But then both Roy and Tony model in EM and OO which could make a difference if only for the deeper flanges which might offer a greater area for the electrics to make their way into the wheels.


Yep, the 'stuff'm-full-o-lead' brigade'.

Just use enough lead so the plastic bits of the track distorts.
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Le Corbusier
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Re: Rigid Chassis Locos?

Postby Le Corbusier » Sat Mar 21, 2020 9:32 am

billbedford wrote:
Enigma wrote:The late Roy Jackson wasn't a believer in 'flexible' chassis either and his locos ran on 'Retford' faultlessly. I remember him saying that he did try compensation at least once, possibly more, but he wasn't convinced by it.

But then both Roy and Tony model in EM and OO which could make a difference if only for the deeper flanges which might offer a greater area for the electrics to make their way into the wheels.


Yep, the 'stuff'm-full-o-lead' brigade'.

Just use enough lead so the plastic bits of the track distorts.


Watching the track sleepers and all flexing on the real thing, that would not be un-prototypical. :D
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Noel
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Re: Rigid Chassis Locos?

Postby Noel » Sat Mar 21, 2020 10:38 am

Le Corbusier wrote:Watching the track sleepers and all flexing on the real thing, that would not be un-prototypical.


It depends on where and when you were watching. Modern high speed track is commonly concrete slab type, and therefore rigid. But then, it doesn't have to cope with steam engine hammer blow.
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Re: Rigid Chassis Locos?

Postby billbedford » Sat Mar 21, 2020 10:42 am

Even with steam era track, ballast is not really very springy
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Le Corbusier
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Re: Rigid Chassis Locos?

Postby Le Corbusier » Sat Mar 21, 2020 11:19 am

perhaps the archive footage I am recalling was track that needed a bit of maintenance? .... I have certainly seen the track flexing with the wooden sleepers moving in their bed. I had assumed that was why the track maintenance gangs were constantly patrolling to pack ballast back in and re secure chairs etc.
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Guy Rixon
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Re: Rigid Chassis Locos?

Postby Guy Rixon » Sat Mar 21, 2020 11:31 am

Le Corbusier wrote:
Guy Rixon wrote:Concerning springing to improve electrical contact, it's worth noting that this is now common practice in 2FS, where spring for track holding don't work much and aren't considered necessary.

From my perspective it is self evidently true that many have experienced issues over the years with electrical contact and developed compensation and springing methods to solve this issue (alongside other issues such as track holding). It is also self evidently true that both methods are successful in delivering improved electrical contact. It is just odd that in both 00 and EM, where track holding is deemed to be less of an issue, there are some extremely prominent kit and scratch builders who build totally rigid chassis which are noted for reliability of running .... its a mystery :?

Perhaps the most-successful rigid locos have more wheels to pick up?

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Noel
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Re: Rigid Chassis Locos?

Postby Noel » Sat Mar 21, 2020 11:36 am

Le Corbusier wrote:I have certainly seen the track flexing with the wooden sleepers moving in their bed. I had assumed that was why the track maintenance gangs were constantly patrolling to pack ballast back in and re secure chairs etc.


Yes. Steam era main lines needed constant attention and were inspected on a daily basis. Branches with less, and slower, traffic perhaps less often, and sidings possibly not at all.
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Tim V
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Re: Rigid Chassis Locos?

Postby Tim V » Sat Mar 21, 2020 12:15 pm

Guy Rixon wrote:Concerning springing to improve electrical contact, it's worth noting that this is now common practice in 2FS, where spring for track holding don't work much and aren't considered necessary.

The 'springs' are actually bearing on top of the axles (split frames), there is usually minimal slop in the bearings. It does improve pickup considerably.
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steve howe
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Re: Rigid Chassis Locos? - Romford wheels?

Postby steve howe » Sat Mar 21, 2020 1:13 pm

This may not be the right place to float this, but recently, wearing my 7mm narrow gauge disguise, I had need to get some Romford wheels from Markits. I know they have been around since Adam was a gricer, but they have over time undergone re-tooling and upgrading and now seem to represent proper prototype dimensions rather than metric sizes. I am wondering if there exists a tool, or maybe an enterprising supplier willing to undertake the work, whereby the wheels can be re-profiled to P4? the main problem I suppose would be the longer axle needed, but would not fine shim washers on the EM axles do the job?

I only suggest this because the Markits range seems to be very extensive, and given the ease of fitting and quartering Romford wheels, it strikes me as being a missed opportunity?

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Re: Rigid Chassis Locos?

Postby billbedford » Sat Mar 21, 2020 4:19 pm

Markits have made P4 axles, whether they still stock them I'm not sure.
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steve howe
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Re: Rigid Chassis Locos?

Postby steve howe » Sat Mar 21, 2020 4:30 pm

billbedford wrote:Markits have made P4 axles, whether they still stock them I'm not sure.


Interesting, I wonder if they do a finer tyre profile than RP25? time for a bit of research I think!
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Re: Rigid Chassis Locos?

Postby Philip Hall » Sat Mar 21, 2020 4:41 pm

I think RP25 is as fine as it gets. 247 Developments used to stock the P4 Markits axles. They also did a nice little etched washer which is useful for increasing the back to back dimension in EM. Turning the wheel down to P4 is quite possible but requires a form tool for a proper job.

One problem (which also applies to rtr wheels) is the thickness of the wheel and the position of the flange in relation to the front of the wheel. Some of these wheels have a nice spoke profile and this would be lost in turning off the front face.

I only have a Unimat SL but have successfully reprofiled some old Jackson wheels to P4 essentially by eye. It takes a long time and it’s debatable whether it’s worth it. I don’t bother with coning and turn a parallel tread which has worked fine, not least because turning a taper on the SL involves moving the headstock which I don’t want to do. Besides, a parallel tread was advocated in the Ward-Platt article republished in Scalefour News 206 and I like the man’s ideas.

Philip

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steve howe
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Re: Rigid Chassis Locos?

Postby steve howe » Sat Mar 21, 2020 5:02 pm

247 Developments list the 'Romford P4 axle' I wonder if RP25 profile tyres would work in P4...... :o

Or is that total heresy?

Steve

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Tim V
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Re: Rigid Chassis Locos?

Postby Tim V » Sat Mar 21, 2020 5:12 pm

steve howe wrote:247 Developments list the 'Romford P4 axle' I wonder if RP25 profile tyres would work in P4...... :o

Or is that total heresy?

Steve

You asked the question, I expect a full report back (and an article for the snooze).
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Re: Rigid Chassis Locos?

Postby Horsetan » Sat Mar 21, 2020 6:49 pm

Tim V wrote:
steve howe wrote:247 Developments list the 'Romford P4 axle' I wonder if RP25 profile tyres would work in P4...... :o

Or is that total heresy?

You asked the question, I expect a full report back (and an article for the snooze).


Maybe you could compare notes with Martin Goodall, he of the "EM/EMF" flange..... :?: ;)
That would be an ecumenical matter.

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Re: Rigid Chassis Locos?

Postby Le Corbusier » Sat Mar 21, 2020 7:36 pm

Horsetan wrote:
Tim V wrote:
steve howe wrote:247 Developments list the 'Romford P4 axle' I wonder if RP25 profile tyres would work in P4...... :o

Or is that total heresy?

You asked the question, I expect a full report back (and an article for the snooze).


Maybe you could compare notes with Martin Goodall, he of the "EM/EMF" flange..... :?: ;)


I might be imagining it ... but I am sure I read an article in either the Smooze or MRJ a while back about a chap who turned down the flanges on EM wheels and ran them successfully on P4 vastly improving reliability and allowing him to play trains with his granchildren ;)
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Re: Rigid Chassis Locos?

Postby Crepello » Sat Mar 21, 2020 8:06 pm

Philip Hall wrote:One problem (which also applies to rtr wheels) is the thickness of the wheel and the position of the flange in relation to the front of the wheel. Some of these wheels have a nice spoke profile and this would be lost in turning off the front face.

Except the Markits have tyres retained by an interference fit. It should be possible to make a press tool to shift the tyres forward on the centres. It would need to be a custom job for each diameter though.

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jon price
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Re: Rigid Chassis Locos?

Postby jon price » Sat Mar 21, 2020 10:18 pm

So clearly mass hysteria is occurring. We are now onto rigid chassis with marginal sloptype springing to increase electrical conductivity, and Markits EM wheels with spacing washers on Romford axles.
Connah's Quay Workshop threads: viewforum.php?f=125

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Re: Rigid Chassis Locos?

Postby Philip Hall » Sat Mar 21, 2020 10:42 pm

I should make it clear that I’m not advocating the reprofiling of Markits wheels to P4, merely that it is possible if you want to go to all that trouble. Generally I don’t. The odd occasions I have done things with Markits wheels have been in response to customers who wanted a thinner flange and greater back to back dimension in EM. Or for a bit of fun to see whether I could produce a P4 wagon wheel by a bit of turning - which it was but it took a fair amount of time. At least it did for me as I have a limited machine capability.

By far the best results in P4 are obtainable with existing wheels like Alan Gibson and Ultrascale.

Philip

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steve howe
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Re: Rigid Chassis Locos?

Postby steve howe » Sat Mar 21, 2020 11:19 pm

In the interests of research, this is Markit's response to my query, make of it what you will:

Dear Sir,

There is good news and there is not so good news…..

The Good News is yes, we do make ‘P4’ Driving Axles….. which are becoming more and more popular, as people decide that the plastic centred wheels from various manufactures are not very user friendly and generally are a one hit wonder…they have to go on right FIRST time or another. new set of wheels are required.

Most people I have spoken to, say that IF when looked at ‘End-On’ our wheels are 2.54mm or 0.100” Wide….. True ‘P4’ should be 2.0mm or 0.088” Wide. Side profile our Prototypical wheels are as good as (if not better than ) alternative manufacturers…WITH the added bonus that they can be taken on and off the Axle as many times as you like and will PROBABLY last a lifetime.

The Not so good news is that NO they CANNOT be re-profiled…..IF you try skimming the BACK of the wheel, you will upset the Back-to-Back.
IF you try skimming the FRONT you will remove the PATTERN and characteristic of the wheel.

Our wheels have been 0.100” wide since before 1971 and at £2000 per tool insert, unless YOU are going to pay for it, it is never going to happen.
The Hobby does not need any more Standards….. ALL the Ready-to-Run manufacturers have settled on ‘00’ (albeit Hornby’s wheel width being 3.0+mm and a bit ‘Steam Roller-ish’) I can assure you that there are NOT enough customers/modellers in ‘P4’ to justify the Tooling costs.

I did try some ‘P4’ 14mm Coach Disc wheels because of a lot of ‘Noise’…. I should have remembered ‘ an empty can makes the most noise’….. so I have not bothered since….having said that we SELL quite a lot of the Driving Axles.

I hope the above is of some help.

Yours faithfully,

M.L.Arscott
For MARKITS (UK) Ltd

Tel: 01923 249711

Philip Hall
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Re: Rigid Chassis Locos?

Postby Philip Hall » Sat Mar 21, 2020 11:58 pm

Just to say that the wheels can be skimmed at the back, I have done this a few times because the customer required an EM back to back of 16.65 mm and the supplied EM axle gives you 16.45mm. This also resulted in a slimmer flange profile (also requested) after I had rounded it off with a file. I wouldn’t like to try and shift a tyre on the centre because they are very tightly fitted (which is why I have been able to turn them) and the flange is therefore slightly in the wrong place for a P4 width wheel. The only useful thing would be if you wanted the square hole fitting; turning the tyre off and force fitting a new tyre (like the Ultrascale made to measure tyres) to give you a P4 result.

I believe that the usual use for the P4 axle is in chassis assembly so that wheels can be dismantled several times and brake gear soldered up etc., before finally fitting ‘normal’ wheels for the one and only time.

Commercially at least this is academic, for as Mr Arscott says, production in P4 is never going to happen because the numbers are too small. The work required to do this turning is also far too great when conventional wheels do the job. I like doing the odd thing like this for fun but when I work out the time it has taken there’s no way it would be economical as a job because the prices you would have to charge would frighten people!

Interesting stuff though...

Philip

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Re: Rigid Chassis Locos?

Postby Philip Hall » Tue Mar 24, 2020 2:00 pm

Although I am still not going to recommend turning down a Markits wheel to P4, I have just spent an hour or so taking a bit off the back of the tyres of some driving wheels to increase the back to back for EM, and also to slim down the flanges a bit. When I had finished, the tyre width came out at 2.3mm, and that was with an EM flange approximating to Ultrascale. Now if the flange thickness was to come down a bit more, as it would do for P4, the tyre would be about 2.2mm wide, which is not excessive when we remember that Sharman wheels were 85thou/2.16mm. So maybe in certain circumstances this would be usable, without having to turn anything off the front of the tyre. Of course, a little bit could be taken off the front and probably wouldn’t notice.

Hope this might be of interest. But I must emphasise, it’s a time consuming job!

Philip

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Le Corbusier
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Re: Rigid Chassis Locos?

Postby Le Corbusier » Tue Mar 24, 2020 5:07 pm

Philip Hall wrote:Although I am still not going to recommend turning down a Markits wheel to P4, I have just spent an hour or so taking a bit off the back of the tyres of some driving wheels to increase the back to back for EM, and also to slim down the flanges a bit. When I had finished, the tyre width came out at 2.3mm, and that was with an EM flange approximating to Ultrascale. Now if the flange thickness was to come down a bit more, as it would do for P4, the tyre would be about 2.2mm wide, which is not excessive when we remember that Sharman wheels were 85thou/2.16mm. So maybe in certain circumstances this would be usable, without having to turn anything off the front of the tyre. Of course, a little bit could be taken off the front and probably wouldn’t notice.

Hope this might be of interest. But I must emphasise, it’s a time consuming job!

Philip

Presumably if you are one of those modellers who uses split axles, you could then also use the axles despite having alterred the critical relationships? Otherwise wouldn't the back to backs be too wide?
Tim Lee


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