Points question

[michaelp]

Is there a way to have point always return automatically to the same diverging route once a train has cleared the point,

I have seen full size points work this way before but wondered whether it could be done with a 00 gauge point, maybe with a spring or electronically?

 

Any help would be great

Thanks in advance

 

Michael

[sp1]

Interesting question - could be useful

[BR60103]

It would require, at least, some sort of detector to tell you when the train had cleared the point.

[PatB]

Do you mean sprung or weighted points where a train passing over them in the facing direction will always take the same route but trains approaching in a trailing direction on either route can pass through without the points being reset?

 

If the latter, it's certainly been done down to at least 4mm scale. I can't give precise references but I've recently been rereading some old (late 60s) Railway Modellers and I know I saw at least one mention of 00 sprung points.

 

Mind you, what worked with 1960s 00 track and wheel standards may not be practical today, with much smaller flanges likely to be more prone to derailing rather than bulldozing the incorrectly set point blade into position.

[Michael Edge]

I've been using sprung points on my layouts in 00 routinely for about 30 years, mostly relying on the spring of the rail itself without a tiebar or mechanism. On Herculaneum Dock all the overhead railway points but one are sprung, mainly because I can't fit point motors into the structure. They cause no trouble with most of the stock, including the Ruston 48DS with Sharman wheels, the only item which is a bit problematical is the very light rail carrier - two bogies with some lengths of rail fastened to them.

[michaelp]

Do you mean sprung or weighted points where a train passing over them in the facing direction will always take the same route but trains approaching in a trailing direction on either route can pass through without the points being reset?

 

If the latter, it's certainly been done down to at least 4mm scale. I can't give precise references but I've recently been rereading some old (late 60s) Railway Modellers and I know I saw at least one mention of 00 sprung points.

 

Mind you, what worked with 1960s 00 track and wheel standards may not be practical today, with much smaller flanges likely to be more prone to derailing rather than bulldozing the incorrectly set point blade into position.

 

Yes but the point I saw always went back to the left hand diverging route regardless of which way atrain had passed over it, it was used in storage sidings and approaching locos (towards the switch blades) were always routed onto a run round line.

[Tel2010]

Is this the sort of thing this thread http://www.rmweb.co.uk/community/index.php?/topic/14303-single-direction-points/ show that you are after,remembered bookmarking it a while ago.

Tel

[michaelp]

I probably haven't explained things clearly, if a loco approached a Y point from the tie bar end it would always follow the left hand route but if a loco travelled over the point from the right hand diverging route the point would move across to allow the loco to pass over then the point would move back for the left hand route.

 

Hope this helps

[phil-b259]

The prototype points you seem to be talking about are known as "self normalising" points. The call to return the points to the "normal" position is made by the signal interlocking which will first check that the route previously set over said points has cleared (either through the passage of a train or the signaller cancelling the route) and the track circuit(s) across said points being clear.

 

In earlier installations, to cut down on the wiring a simpler version was used in the sense that once the route was cancelled a buzzer would sound and signaller would have to return the points to the normal position using their points switch.

 

To achieve the same effect in model terms suggests the need for some for of train detection (so as to avoid swinging them under a train) if you want to go down the 'manual' method outlined above plus some control circuitry / computer control if you want the points to self normalise automatically.

[michaelp]

The yard point in question wasn't connected in any way to a signal box or ground frame, infact, as far as I can remember it didn't have a lever for manual switching, the point was self operating.

[beast66606]

The prototype points you seem to be talking about are known as "self normalising" points. 

 

Trailable points - for example gas bags, self-normalising are a different thing.

 

In model form I've made trailable points with no moving parts, it's possible to make them work in a facing direction by careful use of check rails and altering the angle of attack the wheels take when approaching the switch, my example was in P4 and it wasn't reliable enough but with wider flanges it's probably easier to force the wheels in one direction every time for facing moves, and make it possible to trail from either direction - these were copper clad.

[phil-b259]

The yard point in question wasn't connected in any way to a signal box or ground frame, infact, as far as I can remember it didn't have a lever for manual switching, the point was self operating.

 

 

Trailable points - for example gas bags, self-normalising are a different thing.

 

Ahh, I missed the bit about the points in question being yard points (though I am aware of a set of sprung loaded trailing points n the main line near Eastbounrne. When I started on the railway they were biased the 'wrong' way so to speak in that it was the 75mph straight route that pushed the blades over, not the 40mph convergeing route - we got through a fair number of stretcher bars / brackets on that end until they were modified to be sprung the other way around 8 or 9 years ago.

[gordon s]

I had turnouts working this way in DCC, but it was a several years back and I can't recall immediately how it was done.  It involved cuts in the track and an electronic detector.  Apologies for being so vague.  I will rack my brains and see what I can come up with.  I'm fairly sure it involved a unit from Bromsgrove Models who sadly have closed down.

[gordon s]

It was probably one of these...

 

http://www.dccspecialties.com/products/hare-ng-reviewmr.htm

[beast66606]

I didn't mention how I did it !

 

Imagine building a normal point but the switch rails ("blades") are soldered and shortened and then filed at the ends, to allow the flanges to pass between them - switchless points they are called, it wasn't my idea, I nicked it off someone else.

[michaelp]

I thought that I could simply put a pin similar to a point motor actuating pin through the hole in the tie bar of a Peco Code 100 Y point, the pin would be attached to a low tension spring under the baseboard to pull the point back across after a train had cleared the switch blades, is it possible to do it this way? 

 

Michael

[BR60103]

Michaelp:

I think Atlas Snap Switches had this feature when they can out, about 60 years ago. The point mechanism operated a light piece of spring wire that held the points in position, but could be pushed over by a train coming in the opposite direction.

I remember as a youngster in the late 50s, seeing an interurban line (the N S & T) that had spring switches at the ends of passing sidings. I was impressed enough to remember it.

There is a park model live steam train in Ontario that has a spring switch on its reversing loop. It can be sprung in either direction.

 

[my original reply though you were asking something else, entirely]

[beast66606]

I thought that I could simply put a pin similar to a point motor actuating pin through the hole in the tie bar of a Peco Code 100 Y point, the pin would be attached to a low tension spring under the baseboard to pull the point back across after a train had cleared the switch blades, is it possible to do it this way? 

 

Michael

 

The hardest thing will be making sure the spring pulls in a straight line, you may want to make a mechanism similar to a motor - i.e a pin (which goes through the tiebar) mounted on a shaft, which is pulled by a spring and held in a "cage".

 

A small hinge could be used, split in half, I've used them for motorising points in areas where a motor was too big, the end of the hinge pin was driven by wire in the tube to the motor, in your case it would not be wire in a tube, it would be a spring. Get brass ones and file a flat on the pin to make drilling for the point pin easier, the brass can be soldered if necessary.

[Izzy]

I probably haven't explained things clearly, if a loco approached a Y point from the tie bar end it would always follow the left hand route but if a loco travelled over the point from the right hand diverging route the point would move across to allow the loco to pass over then the point would move back for the left hand route.

 

Hope this helps

 

This should be fairly easy to arrange, but as always the devil is in the detail, in that it revolves around having blades that move without easily without much effort being needed, and a spring bias that keeps them in place but which the lightest piece of rolling stock can move over when needed.

 

If using say, Peco points, then removing the fitted over-centre spring should make them easy to move, and a bias spring could be a long wire one which can be easily adjusted to give the right degree of springing. By this I'm thinking of some steel piano wire underneath running perhaps the length of the point, bent up at right angles to move the tie bar, and the pivot/fulcrum point moved along (as is done with the tortoise/cobalt motors) until the right amount of pressure is delivered. Crude and simple, but effective and adjustable.

 

Izzy