Point lever

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GTB
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Re: Point lever

Post by GTB » Tue Oct 23, 2018 9:17 am

tom_tom_go wrote:
Mon Oct 22, 2018 4:47 pm
Graeme, does the point you are installing need to reset the same way each time? If so, just use a spring or a piece of wire to allow it to reset each time.
That's one of the alternatives I'm considering, but I'd like to run trains in both directions on the mainline. A spring soft enough to allow all my rolling stock to trail the point blades may be too soft to adequately lock them against facing movements.

I'll probably end up making some pneumatic point motors and remote control all the turnouts on the triangle from an easily accessible location. Or buy the bits, the cost is about the same as using r/c servos, with no electrickery involved and less parts to go wrong.

Regards,
Graeme

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Re: Point lever

Post by ge_rik » Fri Oct 26, 2018 6:48 pm

GTB wrote:
Mon Oct 22, 2018 4:12 pm
I'll be interested to see how you go with making the point blades trailable.

One of the turnouts on my planned triangular junction won't be easily accessible when the bridge is in place. I've been contemplating how to make it trailable so I don't have to install a remote lever, but haven't cut metal yet.

Regards,
Graeme
Hi Graeme
Not much success so far. I have altered the geometry on my prototype so the lever lies almost horizontal after throwing the blades, thereby increasing the effort needed to raise the weight when flanges pass through. However, the weight is insufficient at present to return the blades so they lie against the stock rails. Partly this is because of inherent friction in the tie bar of the Piko point. I'll try increasing the mass of the balance weight and reducing the friction on the tie bar - but I suspect there is a critical point at which the mass of the balance weight will prevent the flanges from passing through.

Interesting stuff, though. I now wish I'd paid more attention in my A Level Physics classes

Rik
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Re: Point lever

Post by IanC » Fri Oct 26, 2018 11:25 pm

ge_rik wrote:
Fri Oct 26, 2018 6:48 pm

Interesting stuff, though. I now wish I'd paid more attention in my A Level Physics classes

Rik
I wish I could remember any of my Physics classes! All long since forgotten :(
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Re: Point lever

Post by FWLR » Sat Oct 27, 2018 8:11 am

ge_rik wrote:
Fri Oct 26, 2018 6:48 pm


Interesting stuff, though. I now wish I'd paid more attention in my A Level Physics classes

Rik
I remember my Physical Classes….. :lol: :lol: :lol: :lol:
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Re: Point lever

Post by IrishPeter » Mon Oct 29, 2018 2:23 pm

Even if you had paid attention in Physics I don't think it would be that much help. In railway applications one has all sorts of real world problems - bird poop, loose grit, slugs leaving trails, etc., etc., which can mess up even NASA's calculations, and they have a bit more than an pocket calculator and a beer mat to work it out with. I have to declare an interest in the results of your experiments as the CLR will hopefully be constructed using trailable points for the passing loops so I can simplify the signalling etc., outside.

Cheers,
Peter in Va
ge_rik wrote:
Fri Oct 26, 2018 6:48 pm
GTB wrote:
Mon Oct 22, 2018 4:12 pm
I'll be interested to see how you go with making the point blades trailable.

One of the turnouts on my planned triangular junction won't be easily accessible when the bridge is in place. I've been contemplating how to make it trailable so I don't have to install a remote lever, but haven't cut metal yet.

Regards,
Graeme
Hi Graeme
Not much success so far. I have altered the geometry on my prototype so the lever lies almost horizontal after throwing the blades, thereby increasing the effort needed to raise the weight when flanges pass through. However, the weight is insufficient at present to return the blades so they lie against the stock rails. Partly this is because of inherent friction in the tie bar of the Piko point. I'll try increasing the mass of the balance weight and reducing the friction on the tie bar - but I suspect there is a critical point at which the mass of the balance weight will prevent the flanges from passing through.

Interesting stuff, though. I now wish I'd paid more attention in my A Level Physics classes

Rik
Traffic Pattern? What pattern? Spuds out; grain in, but cattle, sheep and passengers are a lot less predictable.

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Re: Point lever

Post by Peter Butler » Mon Oct 29, 2018 4:15 pm

This observation may be of no use at all, but the Peco SM32 points have over-centre-springs, strong enough to hold the blades in either direction, and which holds in position following a vehicle trailing through. I take advantage of this using a cable system with no lever, just a push-pull action.
Do the 45mm gauge points not have a similar spring? If not, could something similar be fitted?
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Re: Point lever

Post by ge_rik » Mon Oct 29, 2018 6:29 pm

Peter Butler wrote:
Mon Oct 29, 2018 4:15 pm
This observation may be of no use at all, but the Peco SM32 points have over-centre-springs, strong enough to hold the blades in either direction, and which holds in position following a vehicle trailing through. I take advantage of this using a cable system with no lever, just a push-pull action.
Do the 45mm gauge points not have a similar spring? If not, could something similar be fitted?
Piko points have a centre spring but to my knowledge, none of the others do.

Rik
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Re: Point lever

Post by tom_tom_go » Mon Oct 29, 2018 6:37 pm

I would be surprised if the Peco SM32 points are not the same design as the G45 type?

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Re: Point lever

Post by ge_rik » Mon Oct 29, 2018 6:42 pm

IrishPeter wrote:
Mon Oct 29, 2018 2:23 pm
Even if you had paid attention in Physics I don't think it would be that much help. In railway applications one has all sorts of real world problems - bird poop, loose grit, slugs leaving trails, etc., etc., which can mess up even NASA's calculations, and they have a bit more than an pocket calculator and a beer mat to work it out with. I have to declare an interest in the results of your experiments as the CLR will hopefully be constructed using trailable points for the passing loops so I can simplify the signalling etc., outside.
Cheers,
Peter in Va
Hi Peter
You're so right about all those variables. Even in the workshop, I'm finding the friction inherent in the point itself is enough to resist the mass of the balance weight. Greg Hunter, who is a mathematical whizz, has been doing some calculations on my behalf, but I think it will also require a fair degree of twiddling, tweaking and fettling to get the balance between theory and practice figured out.

If i manage to get some definitive answers (positive or negative), I'll post them here.

Rik
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Re: Point lever

Post by ge_rik » Mon Oct 29, 2018 6:44 pm

tom_tom_go wrote:
Mon Oct 29, 2018 6:37 pm
I would be surprised if the Peco SM32 points are not the same design as the G45 type?
Sounds reasonable, Tom. I'm using code 332 rail though, so not had experience with Peco which I think uses code 250.

Rik
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Re: Point lever

Post by GTB » Tue Oct 30, 2018 1:40 pm

ge_rik wrote:
Mon Oct 29, 2018 6:42 pm
If i manage to get some definitive answers (positive or negative), I'll post them here.
I know it can be done in the ride-in scales, as we built some many years ago on a 7.25" garden railway and my mate has one on his current 12" gauge line. However locos. weighing 1-2 tons and rolling stock weighing 200-500lbs don't suffer from the scaling issues encountered in smaller scales. Being able to use a steel offcut weighing a couple of kg as the counterweight on the point lever also helps.

We made some that always returned to the same position and had to be manually held over for the other route when making facing moves. These had the lever biased to one side so it worked between about 85deg and 45 deg.

The 7.25" line had a zig-zag to get down the hill from the workshop and those two point levers were arranged differently. When trailed they returned to the direction they had been set for, so the lever worked symmetrically between about +/-40 deg in both directions.

One of the things we found in large scale which may be relevant in garden scale was that the point lever had to work over a fairly small angle, no more than 45 deg from vertical as I remember. We found that if the lever was laid over too far, the smaller wagons tended to climb over the point blades and derail rather than trail through them. The lighter (relatively speaking) weight on the wheels meant the flanges didn't have the leverage to move the point blades if the point lever was laying flat.

I disagree with Peter, most of the variables are maintenance issues and a mathematical model of a model turnout would be a trivial job for the likes of NASA or Boeing. That sort of thing is above my pay grade though......

The Peco over-centre spring for closing the point blades was mentioned earlier in this thread and this design has been used for donkeys years by various manufacturers. Looking at your photo, Piko use it in their turnouts and there may well be one buried in LGB turnouts.

The over-center spring is used in turnouts designed for use with track power and closes the point blades with more force than needed if track power isn't being used. I doubt they can be trailed unless the spring is removed.

My workbench is covered in tools and track support parts and will be for some time, so I'm not going to be doing any work on this until I get some track laid. I look forward to your experience and conclusions though, whatever the result.

Regards,
Graeme

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Re: Point lever

Post by Robert Hammond » Sun Dec 09, 2018 2:17 pm

I like your point levers. I will try that method as and when my Tenmill ones start to wear out. See my post on 'long distance point control' in 'help and advice'.

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