Peco Bullhead Points: in the flesh

[JohnR]

On 28/09/2019 at 18:05, martin_wynne said:

 

The correct back-to-back for the wheels on 00 RTR models  is 14.4 mm -- see: http://www.doubleogauge.com/standards/commercialwheels.htm

 

The other back-to-back gauges available are for other types of wheels.

 

A 14.4mm back-to-back gauge is available from: http://www.doubleogauge.com/shop.htm

 

You want the Intermediate version.

 

cheers,

 

Martin.

 

 

 

Yes, but which B2B dimensions will ensure that stock runs smoothly through these points? I am cynical enough to think that it may not be the same for every point on the market....

 

[martin_wynne]

36 minutes ago, gr.king said:

Some of the decisions on standards made by the DOGA seem very odd and retrograde to me. I feel that most serious users of versions of OO that are better than "toy-market coarse scale" have for decades considered 14.5mm to be the minimum standard. Unless the intention is to run models mostly on old style code 100 or worse, practical experience rather than mathematical theory would suggest to me that 14.5 or more is the setting that will actually give best results.

 

The actual standard is that the check gauge is 15.2mm. This is the most important and significant dimension from which all others are derived. For track it is a minimum dimension. For wheels it is a maximum dimension.

 

To find the optimum back-to-back for any given wheel (it's not the same fixed dimension for all wheels), you subtract the effective flange thickness from the check gauge.

 

For modern RTR wheels the effective flange thickness is 0.8mm (NMRA RP25/110). Subtracting that from 15.2mm gives 14.4mm as the maximum back-to-back for RTR wheels.

 

The traditional 14.5mm back-to-back is for what used to be called "Scale 00" wheels, such as Romford/Markits etc., which have 0.7mm flange thickness.

 

Some of the current kit wheels sold for 00 are the same as those sold for EM with a flange thickness of 0.6mm. For those the back-to-back should be 14.6mm.

 

cheers,

 

Martin.

[gr.king]

Notwithstanding the theoretical maximum 14.4mm BTB for RP25/110 wheels, all of my RTR stock, possibly (or probably) including some examples with even thicker flanges now has a minimum 14.5 mm BTB and passes through Peco code 75 FB pointwork when necessary without trouble, every time. The extra width of the BTB also suits a lot of hand made pointwork to finer standards.

 

It is hard to exclude the possibility of unintended variations in dimensions even in mass produced, "standard" pointwork. Hence, I believe, the mathematically correct wheel settings based on the intended dimensions of the track will not always be the most effective ones in practice. I simply follow a scheme that works. 

[47137]

I use two B2B gauges: one 14.4 mm, the other 14.5 mm. I set the wheels so the smaller gauge goes in and the larger one doesn't. All my 00 and H0 RTR runs through Peco code 75 (FB and BH ranges) and 00-SF point work, and this works for me.

 

- Richard.

Edited September 30, 2019 by 47137

[47137]

1 hour ago, 47137 said:

I use two B2B gauges: one 14.4 mm, the other 14.5 mm. I set the wheels so the smaller gauge goes in and the larger one doesn't. All my 00 and H0 RTR runs through Peco code 75 (FB and BH ranges) and 00-SF point work, and this works for me.

 

- Richard.

 

For clarity - I should add, all of my RTR was either made in the last twenty or so years, or has been re-wheeled. But to be honest, my only re-wheeling to allow running (as opposed to improving appearance) has been some Lima from the 1970s/80s. I do think, using a pair of gauges lets you know the dimension is where you want it. I have a suspicion my early 2000's Trix loco has a B2B of around 14.3 mm (by design) and is unhappy on my 00-SF, but this is very much an issue with the Trix wheels. It doesn't go on this part of my layout.

 

- Richard.

[Chamby]

Where I have had problems with RTR running through Peco’s bullhead turnouts, I have used the DCC Concepts 14.5mm gauge to re-set the back-to-backs, and it has fixed the problem every time.

 

I’m sure that the comments above about 14.4mm are correct, but evidently the tolerances involved allow for 14.5mm as well.

[Damo666]

2 hours ago, Chamby said:

Where I have had problems with RTR running through Peco’s bullhead turnouts, I have used the DCC Concepts 14.5mm gauge to re-set the back-to-backs, and it has fixed the problem every time.

 

I’m sure that the comments above about 14.4mm are correct, but evidently the tolerances involved allow for 14.5mm as well.

Thank you for that. I spoke to DCC Concepts and they suggested their 14.75mm B2B gauge. Seems though the general consensus here is 14.4mm or 14.5mm.

 

Would 0.1mm make a difference? on RTR locos

[peterfgf]

On 30/09/2019 at 11:59, 47137 said:

 

For clarity - I should add, all of my RTR was either made in the last twenty or so years, or has been re-wheeled. But to be honest, my only re-wheeling to allow running (as opposed to improving appearance) has been some Lima from the 1970s/80s. I do think, using a pair of gauges lets you know the dimension is where you want it. I have a suspicion my early 2000's Trix loco has a B2B of around 14.3 mm (by design) and is unhappy on my 00-SF, but this is very much an issue with the Trix wheels. It doesn't go on this part of my layout.

 

- Richard.

I think these are known as GO-NO GO gauges. Excellent idea.

Peterfgf

[martin_wynne]

This may be of interest re the latest Hornby wheels and back-to-back:

 

 http://85a.co.uk/forum/view_topic.php?id=3514&forum_id=1&jump_to=27938#p27938

 

It does illustrate the need actually to measure the wheels if you want to set the optimum back-to-back, and not assume they are all the same.

 

cheers,

 

Martin.

[Guest Jack Benson]

Sorry guys but,

 

We are about to embark upon building a simple inglenook diorama and we planned to use two Peco BH 75 large turnouts. The intended motive power is a bog standard new Bachmann 03.

 

Should we be using these products or is there a risk of failure? We could just as easily revert to Peco FB 75 medium  turnouts with Peco BH plain track, we have been using these without issue for thirty years.

 

Thank you

 

JB

[hayfield]

JB

 

I don't use Peco 4 mm RTR track, but why do people think a company like Peco who specialise in trackwork would bring out a product with a risk of it failing ? Just because its to 4 mm scale rather than 3.5 mm scale and uses a rail profile which is more or less bullhead does not mean its inferior to its H0 scale flat bottom track.

 

All products (whoever the company) stand the risk of failing if the makers instructions are ignored or the buyer decides to make their own modifications. Keep to Peco's instructions and it will not only work well but if you are a 4 mm modeller it will look far better than its H0 predecessors    

[Harlequin]

3 hours ago, Jack Benson said:

Sorry guys but,

 

We are about to embark upon building a simple inglenook diorama and we planned to use two Peco BH 75 large turnouts. The intended motive power is a bog standard new Bachmann 03.

 

Should we be using these products or is there a risk of failure? We could just as easily revert to Peco FB 75 medium  turnouts with Peco BH plain track, we have been using these without issue for thirty years.

 

Thank you

 

JB

 

Hi Jack,

 

There's a small potential issue because the isolating gaps in the closure rails of the BH points are very close to the crossing. This means that if you have wheels with back-to-back distances that are incorrectly set too close the tread of a wheel could be riding on one closure rail while it's back is touching the other. Since the closure rails on Unifrog points are electically bonded to the stock rails this means that a short circuit can be momentarily created.

 

Certain types of bogies and pony trucks that allow the wheels to "crab" across the tracks make this problem more likely.

 

However: If the back-to-backs are set correctly this shouldn't be a problem - and back to back distances can be adjusted, of course.

 

I wouldn't expect a Bachmann 03 to have any problems.

 

(Note that the older FB turnouts have the isolating gaps further down the rails, where it's basically impossible for badly adjusted back-to-backs to cause any problems and the closure rails are not electrically bonded to the stock rails by default anyway.)

 

Edited October 8, 2019 by Harlequin

[Gilbert]

9 minutes ago, Harlequin said:

 

Hi Jack,

 

There's a small potential issue because the isolating gaps in the closure rails of the BH points are very close to the crossing. This means that if you have wheels with back-to-back distances that are incorrectly set too close the tread of a wheel could be riding on one closure rail while it's back is touching the other. Since the closure rails on Unifrog points are electically bonded to the stock rails this means that a short circuit can be momentarily created.

 

Certain types of bogies and pony trucks that allow the wheels to "crab" across the tracks make this problem more likely.

 

However: If the back-to-backs are set correctly this shouldn't be a problem - and back to back distances can be adjusted, of course.

 

I wouldn't expect a Bachmann 03 to have any problems.

 

(Note that the older FB turnouts have the isolating gaps further down the rails, where it's basically impossible for badly adjusted back-to-backs to cause any problems and they are not electrically bonded to the stock rails by default either.)

 

I am well on with a layout using the new track and incorporating an inglenook as the main operation. I have used a variety of current Bachmann and Hornby locos with no problems at all.

Chris

[Guest Jack Benson]

Thanks to Chris and Phil for their words of encouragement.

 

Much appreciated

 

Cheers

 

JB

[NIRCLASS80]

Just a note to say that if anyone is concerned about reliability of this track I have a layout built since this track was first introduced and used almost daily all year round and have no issues. 

I run DCC and the points have not been modified in anyway. 
 

I have included a short video just to show it in action. 

 

[Vistisen]

On 23/08/2019 at 17:45, Peter Kazmierczak said:

Welcome to Kings Cross Garden Centre.

Its good for the CO2 balance! Seriously though,  unless it causes operational problems, then why spray even more chemicals into the ground to kill the weeds? As a point of 'minor' interest. I would have thought that all the oils and heavy metals that soak into ground under heavily used railways would kill off most weeds. What are the species in this photo?

[phil-b259]

On 08/10/2019 at 16:24, Vistisen said:

Its good for the CO2 balance! Seriously though,  unless it causes operational problems, then why spray even more chemicals into the ground to kill the weeds? As a point of 'minor' interest. I would have thought that all the oils and heavy metals that soak into ground under heavily used railways would kill off most weeds. What are the species in this photo?

 

The point about weed strewn ballast is that the plant matter prevents the ballast from doing its job of allowing water to drain away. This in turn means water pools near the surface increasing the chances of 'wet beds' developing - which not only increase the risks of rails breaking, but they can also adversely affect track circuit reliability.

 

Granted at a termini like Kings Cross poor track quality is unlikely to be as big issue as it would be than on the railway proper, but its still not a good thing to let happen generally.

 

Also, as has been explained many times the chemicals which can be sold to deal with weeds these days must meet strict environmental standards - which basically means they become completely harmless the moment they enter watercourses, or come into contact with bare ground etc. To actually have any effect they must be spayed directly onto the plant itself (and not washed off by rain in the subsequent hours) which allows the chemicals to be absorbed.

 

Back in BR days, the preferred weedkiller (now completely banned in the UK) was basically the same stuff the USA used to spray to clear vegetation in the Vietnam war. Highly toxic if it gets into watercourses, not to mention carcinogenic to those who prepare it, 'Agent Orange' does however linger in the soil for extended periods killing anything that might be tempted to start growing.

 

* Wet Beds

http://www.mortonroberts.com/railway_track.jpg

https://www.youtube.com/watch?v=oB0mSUh4DUc

 

 

[jamespetts]

Some updates from Warley: there was a pre-production sample of the medium radius bullhead turnout:

 

Peco bullhead by James Petts, on Flickr

 

and a sample of the double slip in a more complete state than previously seen:

 

Peco bullhead by James Petts, on Flickr

 

but the release of these has again been delayed, the latest information being that they are now expected in Q1 2020. The person on the stand to whom I spoke said that these had proved a "nightmare" to tool, but that they would be worth it when they arrived.

 

Here is the buffer stop:

 

Peco bullhead buffer stop by James Petts, on Flickr

Edited November 23, 2019 by jamespetts

[Tom F]

Apologies if this has already been asked, I just wondered what the current ETA was on the medium points.

[PMP]

I’ve not heard specific estimates for the mediums so far, except for this year. 

[mdvle]

The Peco Spring Report (see other thread this section) just mentions arriving 2020 - given that the North American code 70 turnouts say arriving soon that would suggest that the medium points aren't imminent.

[jamespetts]

I notice that this video on Peco's channel about rebuilding one of the Pecorama layouts with Bullhead track has a track plan featuring single and double slips, and paper templates of the single and double slips are shown in the video.

[Dr Gerbil-Fritters]

Those look to be templates for the current code 75 track, not the new BH ones...

 

In my experience, everything in Peco land seems to be 'coming soon', sometimes for decades...

[Gilbert]

53 minutes ago, Dr Gerbil-Fritters said:

Those look to be templates for the current code 75 track, not the new BH ones...

 

 

Are the new points not the same footprint  as the code 75 none BH? In which case the templates will be fine?

Edited March 4, 2020 by Gilbert

[Dr Gerbil-Fritters]

Somewhere I think I've seen mention that they are the same, which caused grumblings from some (as the slips are notoriously small radius) and there was a hope they might have been more generously proportioned, along the pattern of the US style Code 83 range.