Crossing SG track with NG track

Tom Haythornthwaite · April 04, 2021, 17:41

QuoteOddly the JHMD uses a single blade where they branch off the SG mainline. But that's probably for safety rather than anything else, the speed limit is about 60mph at that point so you don't want derailments!

Why 'oddly'? Where would any other blade go?

B.Meldon · April 04, 2021, 17:48

The main issue you will find is all about the flange gaps.
On real railways the flange gaps are virtually the same for both SG and NG, but in model form you will find that the flange gaps need to be bigger for the SG and this then creates issues with the smaller NG wheels sort of dropping down the gap.
One way around this is to only use fine scale SG wheels, but this basically rules out any ready to run SG items as they all have bigger flanges.
With the Tillig track we found that the flange gaps were too small for many of the SG items we had and that they were also too big for some of the NG items, so the worse of both worlds! We also found that the dead frog caused the NG locos to stall at slow speed.

In the end we made a point with a moving frog section, much like a quarry stub point and a single blade, this works very well indeed for both the SG and NG. For a long time, we thought there was not a prototype for this, but then we found one in eastern Europe! The point was built on a seperate section of the 1/4 (6mm) ply track bed that once compleated with the mechanisun was inserted into the layout. All the dual guage track is made using SG rail with a transition section where it joins the NG. Here is a photo, it is switched to the NG, this was before the scenery was done in this area of the layout:

Hobby · April 04, 2021, 18:35

Quote from: Tom Haythornthwaite on April 04, 2021, 17:41Why 'oddly'? Where would any other blade go?

If you look at the Tillig photo there isn't a blade at all.

Dave Cooper · April 04, 2021, 19:48

That's a neat solution Brian. I don't know if I could build one but, it would be fun to try !
Regards,
Dave

Dave Cooper · April 05, 2021, 11:40

Trying to improve the CAD skills a bit ! This is the latest proposal at the shed end. The assumption here is that the wheel flanges will steer the loco's down the appropriate track...

This being OK, I'll follow up with a diagram of the crossing

Hobby · April 05, 2021, 12:11

Yes that should work OK, I'd wire it up as a complete section for the shed, with a DPDT switch to change it from SG to NG. Actually quite a neat solution and a lot simpler!

Dave Cooper · April 05, 2021, 15:25

Thanks Blair

I'm a great one for simplicity ! Yes, a dedicated DPDT shed switch sounds like a good idea.

It's the crossing next (I'm expecting some electrical trickery may be necessary...)

Dave

Dave Cooper · April 05, 2021, 15:56

Proposed Crossing SG /NG. Any tips on wiring, rail heights, flangeways, check rails etc. greatly received. I'll probably have a bash at making this up myself...

Dave Cooper · April 05, 2021, 16:05

Forgot to mention - all points (SG & NG) are Peco Electrofrog.

JulienW · April 05, 2021, 21:09

Couple of thoughts:

As a short cut I wonder if buying a ready made crossing and cutting it up might be one way to go. I'd suggest that starting with a OO or HO (so 16.5 mm gauge) crossing and cutting a 7.5 mm wide strip from between the rails on one of the routes to convert it to 9mm gauge would be easier than taking a 9mm gauge crossing and making one of the routes wider. Either way you'd get all the check rails and flangeways set correctly, and if you get a live frog crossing then the electrical side of things should also be sorted (just follow the instructions that come with the crossing).

Some time ago Society member Keith Angus produced a set of templates to make various 009 points based on Peco geometry bit with more variety of radii (including double-curve points).I can't recall exactly what was covered but I think dual gauge crossings were included though perhaps not as big an angle as you'd like. They would, however, give you an idea of what goes where (flangeway gaps, check rails etc.) and electrical gaps. Keith's copyright allows for distribution as long as it is not for profit and full credit is given, so if you'd like to message me with an email address I can send you the pdf files.

As to rail height it probably makes sense to have both gauges on the same section so if going down the hand built route then it may be worth stripping some flexitrack for its rail as you aren't going to need much for a single crossing.

B.Meldon · April 05, 2021, 21:18

Quote from: Dave Cooper on April 05, 2021, 15:56
Proposed Crossing SG /NG. Any tips on wiring, rail heights, flangeways, check rails etc. greatly received. I'll probably have a bash at making this up myself...

The first thing you need to know is what wheel profiles are you going to use on the SG locos and rolling stock.
If you use anything other than fine scale then the flange gaps will be too big for the NG.
Basically, you need to use the same wheel profiles for the SG as you do for the NG.

In regard to the wiring, you really need it to be all electrofrog to do this you need to use isolating fishplates and connect the rails as shown on this version of your diagram with four sections, I will work out the switching, but it will need a DPDT switch to select narrow or standard gauge.

Dave Cooper · April 06, 2021, 11:13

Thanks for the replies and further info' both.

Julian : As luck would have it, I've got an old Lima 00 diamond crossing (I suspect about 30 years old now !) still in it's original packaging but no wiring instructions as far as I can remember. As you say, may be a useful source of parts...

Brian: Great mod to the diagram - the colours make it easy to follow. As for wheel profiles, it's whatever came with the loco's, kits and stock :

NG - Kato 4-wheel chassis. Farish 08 shunter chassis. Scratch-built wagon on a standard N gauge chassis.
SG - Bachman (04 ?) Shunter. Mainline J72t. Lima DMU. Hornby "Smokey Joe" tank. Hornby "Rothersay Industries" tank. Ratio Brake, Ventilated vans and Clay wagon. Old Triang tanker and coach (coarse scale I would think). A right old mix ! All will run on the current (SG Code 75 /NG Code 80) track nicely. The exception being the old Triang stuff which hits the chairs and is noisy but will run !

I'll be using a DPDT switch in the shed to switch between SG and NG. Just wondering if this could do 'double-duty' at the crossing as well maybe ? If not, an extra switch is fine operationally.

Dave

Hobby · April 06, 2021, 11:23

Quote from: Dave Cooper on April 06, 2021, 11:13I'll be using a DPDT switch in the shed to switch between SG and NG. Just wondering if this could do 'double-duty' at the crossing as well maybe ? If not, an extra switch is fine operationally.Dave

I can't think why it wouldn't work that way.

Dave Cooper · April 07, 2021, 21:13

Just measured up the old Lima diamond crossing and it's much too big for the location.

I think it's got to be a 'tailor-made' job. Possibly, I may be able to use some of the crossing parts at the intersection of the 4 rails though....

Julien, if I may, I'll take up your offer to forward some templates and pm you my email address.

Thanks,
Dave

Hobby · April 08, 2021, 07:57

I know it looks nice, Dave, but is it really necessary? The vast majority of interchange stations between SG and NG I've seen have all of the NG onj one side, the side where the NG branches off to it's destination, so no need for it to cross the SG. Apart from the cost of the crossing you have to factor in that the crossover has to be signalled to be used safely so that makes it even more unlikely!