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Peco Bullhead Sleeper Spacing


E100
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I'm interested in using Peco code 75 Bullhead for a layout in the future. I have a [silly] question I haven't been able to find an answer to is what the spacing is based on. The gauge of 16.5mm means if the sleepers are spaced at 4mm prototyical spacing then in isolation the track looks strange with the sleepers spaced too far apart relative to rails . On the flipside if they are spaced relative to the gauge of 16.5m then are we not back at square 1 which I assume is the whole reason standard streamline looks unprototyical. 

 

I assume the truth lies somewhere between and that you can manipulate this somewhat with the sleeper spacing anyway.

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I assumed track was actually HO scale, so sleeper spacing would match that, ie every 7mm as per code 100 track. I have noticed that Peco code 83 is actually 6mm spacing to suit USA standard.

Odd thing is that the old Hornby Dublo OO track(final series ) is 8mm spacing, and actually looks better for OO scale.

It is always going to be a compromise when you use 16.5mm gauge for 4mm scale, wich is why I now tend to match track to scale I am modelling in. I tend to try and find supplies of old HD track as well as old Formaway and GEM trackd  for 4mm scale, and am now looking at using code 83 for 3mm scale broad gauge.

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5 hours ago, E100 said:

I'm interested in using Peco code 75 Bullhead for a layout in the future. I have a [silly] question I haven't been able to find an answer to is what the spacing is based on. The gauge of 16.5mm means if the sleepers are spaced at 4mm prototyical spacing then in isolation the track looks strange with the sleepers spaced too far apart relative to rails . On the flipside if they are spaced relative to the gauge of 16.5m then are we not back at square 1 which I assume is the whole reason standard streamline looks unprototyical. 

 

I assume the truth lies somewhere between and that you can manipulate this somewhat with the sleeper spacing anyway.

The sleeper spacing is roughly 6mm spacing. I’m unaware if it was based on anything specifically, apart from getting the visual proportions correct. The support webbing underneath is similar to the traditional streamline type but not as thick so cuts easier to alter spacing and ease of ballasting. 
C30C0669-ADF0-4D15-A4D0-6424B72513C3.jpeg.e354bc06efc9d5acd23e20013d2149c9.jpeg

 

Here’s the bullhead track with a section of traditional CD75 streamline dropped in the foreground for comparison. I don’t understand why @rue_d_etropal  thought it was going to be HO, the concept is to make track that looks better for OO gauge 4mm scale, and was designed to meet that criteria. It certainly hits the mark in that regard, and I’m aware of some European HO modellers using it to represent HO bullhead track.

Here’s what it looks like with the Peco Bullhead points, wired with Tortoise motors.

78AB6641-A89E-48A5-BAA9-AF0D91495BE4.jpeg.c49f529f3a616a14ce65a55e7b070482.jpeg


So far my experience of it is it’s user friendly, a bit more fragile (to be expected), than CD75 streamline, and gives good looking, and reliable trackwork. 
 

 

 

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5 hours ago, E100 said:

I'm interested in using Peco code 75 Bullhead for a layout in the future. I have a [silly] question I haven't been able to find an answer to is what the spacing is based on. The gauge of 16.5mm means if the sleepers are spaced at 4mm prototyical spacing then in isolation the track looks strange with the sleepers spaced too far apart relative to rails . On the flipside if they are spaced relative to the gauge of 16.5m then are we not back at square 1 which I assume is the whole reason standard streamline looks unprototyical. 

 

I assume the truth lies somewhere between and that you can manipulate this somewhat with the sleeper spacing anyway.

 

It's worth pointing out that there was - and is - no single standard sleeper spacing on the network. 

 

The commonly quoted 4mm value of  spacing at 10mm centres equates to 2'6" in real life and appears to date from the original BRMSB standards of 1943. It is accurate for 1930s mainline practice. The BRMSB themselves also quoted 12-14mm centres on sidings : I doubt if many people have been bold enough to do that in recent years. We would probably regard it as shockingly spidery after years of viewing  tightly spaced HO sleepering conditioning our expectations.

 

By the 1950s , BR mainlines were being relaid wih sleepers at 2'4" centres (a whisker over 9mm) and I think even tighter spacing is used nowadays on  high speed main lines. Going in the other direction , I have seem values of 2'8" to 2'10" quoted as specified by various pre=Grouping companies (I think buckjumper posted some values on here long long ago...). These will apply to main lines - branch lines will often have had more widely spaced sleepering. Sidings were even wider spaced

 

So "4mm prototype spacing" could be anywhere between about 8.5mm centres and 14mm centres, depending on how heavily trafficked the piece of track was, and when it was laid. Plenty of wriggle room there.

 

Peco Streamline has traditionally been made at 7.5mm centres - a lot tighter than any prototypical 4mm spacing. In the extreme, lightly laid sidings might be laid at almost twice that spacing.

 

I have seen 9mm centres quote for the new Peco bullhead , though I don't have any to hand to measure. I assume PMP's 6mm figure is the gap between the sleepers. This raises another issue - HO Peco Streamline also looks wrong for British practice because it uses matchstick sleepers, that are too thin and too short for 4mm British track. With wider centres you can also have wider sleepers without the gap between them looking wrong. A 20% increase in sleeper centres  (7.5mm to 9mm) could easily support a 25% widening of the sleeper itself. That's a big change in sleeper size.

 

A comprison between Peco's code 75 concrete sleeper track and it's code 100 equivalent is instructive. The code 75 concrete sleeper flexitrack is not accurate for 4mm - but it has  modestly increased centres, and wider, longer sleepers , so it looks a lot more authentic than the old code 100 flexi

Edited by Ravenser
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1 hour ago, Ravenser said:

 

It's worth pointing out that there was - and is - no single standard sleeper spacing on the network. 

Excellent point. I also really appreciate the additional information you've given as well. It would be nice to model a junction based on these principles.

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Don't forget too that on jointed track at one time the sleeper spacing changed towards the rail ends.

 

 

Overall it really boils down to how we perceive the appearance of the track in an overall setting.  Back in the day ( a long way back) I simply couldn't get on with the flex-track sleeper spacing on streamline - it just looked 'wrong' hence it was a long way from my preference.  The Code 75 track didn't look quite so bad but of course various alternatives such as SMP were becoming available.  To me the Peco bullhead track looks believable so I'm happy with it and in the end I think it will boil down to personal choice for most people.

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I have a piece here, which I've just measured at multiple different points along the length as accurately as I can with my digital calipers. Dimensions (to 1 decimal place) are as follows:

 

Gap between sleepers = 5.9mm

Width across 2 sleepers = 12.9mm

Width of sleeper = 3.5mm

 

This gives a sleeper spacing  of 9.4mm centre-to-centre. I double-checked this by measuring the distance over 20 sleepers, which came out at 188mm thus confirming 9.4mm. That's around 2' 4 1/8" at 4mm/foot.

 

Hope that helps,

 

Jonathan

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On 29/06/2021 at 17:38, Ravenser said:

 

It's worth pointing out that there was - and is - no single standard sleeper spacing on the network. 

 

The commonly quoted 4mm value of  spacing at 10mm centres equates to 2'6" in real life and appears to date from the original BRMSB standards of 1943. It is accurate for 1930s mainline practice. The BRMSB themselves also quoted 12-14mm centres on sidings : I doubt if many people have been bold enough to do that in recent years. We would probably regard it as shockingly spidery after years of viewing  tightly spaced HO sleepering conditioning our expectations.

 

By the 1950s , BR mainlines were being relaid wih sleepers at 2'4" centres (a whisker over 9mm) and I think even tighter spacing is used nowadays on  high speed main lines. Going in the other direction , I have seem values of 2'8" to 2'10" quoted as specified by various pre=Grouping companies (I think buckjumper posted some values on here long long ago...). These will apply to main lines - branch lines will often have had more widely spaced sleepering. Sidings were even wider spaced

 

So "4mm prototype spacing" could be anywhere between about 8.5mm centres and 14mm centres, depending on how heavily trafficked the piece of track was, and when it was laid. Plenty of wriggle room there.

 

Peco Streamline has traditionally been made at 7.5mm centres - a lot tighter than any prototypical 4mm spacing. In the extreme, lightly laid sidings might be laid at almost twice that spacing.

 

I have seen 9mm centres quote for the new Peco bullhead , though I don't have any to hand to measure. I assume PMP's 6mm figure is the gap between the sleepers. This raises another issue - HO Peco Streamline also looks wrong for British practice because it uses matchstick sleepers, that are too thin and too short for 4mm British track. With wider centres you can also have wider sleepers without the gap between them looking wrong. A 20% increase in sleeper centres  (7.5mm to 9mm) could easily support a 25% widening of the sleeper itself. That's a big change in sleeper size.

 

A comprison between Peco's code 75 concrete sleeper track and it's code 100 equivalent is instructive. The code 75 concrete sleeper flexitrack is not accurate for 4mm - but it has  modestly increased centres, and wider, longer sleepers , so it looks a lot more authentic than the old code 100 flexi

 

It's a great pity the Peco didn't decide to go for the good running obtained with 00-SF 16.2mm gauge.

 

Dave.

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