Sprung points and dcc control

[Dan Griffin]

Good morning.

 

I am in the planning stages of my new layout, and am planning a joint colliery railway/preservation centre branch line.

 

the idea is that this branch will go out through the garage wall and off into the garden, a length of about 65ish feet.

 

In the garden shed at the end I plan to have a loop which will double up as a coal loading point,

 

it will be dcc operation and my question is on DCC operation can you use sprung points, so that a coal train, or indeed a steam loco and three coaches, can run round the loop and back to the garage without me having to go out and move the points myself.

 

On the diagram A is where the railway will run through the wall and into the garden.

 

the blue line denotes where the colliery branch/ preservation centre  boundary.

 

B is the set of points in question. the train will travel around the loop and hopefully come back through this point, if its electrically possible, using a weak spring to allow the points to reset normal after the passage of the trains. I understand I will also need a reverse loop module.

 

I have tried to be as clear as possible, and hopefully someone can point me in the right direction.

 

 

 

 

[njee20]

You don't say what gauge you're running in, but yes, it's possible if the points are so designed. In N gauge Fleischmann points work in this way, and I belive Kato Unitrack ones may do too.

 

I presume you're using OO (or larger) though. You can certainly modify Peco points to work as 'slave' points for the trailing direction, but I suspect you'd run into problems running stock through them in a facing direction, particularly as I'm sure you want reliability given the location. 

 

What may be better is a reverse module like the PSX-AR which can also activate a point motor so that it's always set correctly.

Edited June 18, 2018 by njee20

[Pete the Elaner]

What gauge are you working in & what points are you using please?

[Dan Griffin]

Sorry its all 00 gauge code 100 peco track

[Phil S]

Sprung points - as common with Tram operation can be used whenever the stock is heavy enough to reliably move the blades across as it passes through, and then allows it to spring back to the 'normal/default' position immediately afterwards - THE OTHER PROVISO - and not mentioned above - is whether the points are 'live frog'  or dead frog - and how the frog polarity is switched ....

 

When a 'sprung point' is entered from the non-default direction, (ie from the route which is NOT set) then the LIVE FROG will be wrongly phased.... because the mechancial switching which may automatically take place with the point blade movement will NOT have occured .... HOWEVER - and  'FROG JUICER or similar Automatic Phaser  DOES NOT REQUIRE the mechanical movement, and therefore can be used to switch the frog independently of the blades position.

 

You will need to check - with your chosen brand - whether the blased switch with the frog or are connected permanently to their adjacent rails - which is the better solution.

[njee20]

The PSX-AR will also switch frog polarity to avoid a short and would still be my recommendation.

You can remove the over-centre spring from Peco points, but they won't reliably work as you want, so you'd need to modify the blades to actually be sprung rather than simply 'floppy'. Sure it could be done, personally I wouldn't though.

[Phil S]

Another option is to deliberately switch the points automatically to the required route - by an opto detector or beam break across the required path (about 4-7GBP oin Ebay - you don't need to automate the other route options but that may be logical.

[Dan Griffin]

Having had a think i could make the loop an out and back, so it would make a double track line and have the points back inside the garage, much like the loop that the flyash used to use at fletton. However having just measured up, the out and back loop would be roughly 214 feet long!

Edited June 18, 2018 by Dan Griffin

[HLT 0109]

A sprung point will reset itself  after each wheelset passes through it will it not - or at least try to?  In those circumstances, would a frog juicer, reverse loop monitor, or a PSX be able to cope with rapid changes in phasing?  I see Dan is thinking of an alternative system but the opto detector seems peferable to me.  Would Dan be able to make the point switch back again with just one detector (after a stipulated delay) or would he need two?

 

Harold. 

[F-UnitMad]

A sprung point will reset itself  after each wheelset passes through it will it not - or at least try to?  In those circumstances, would a frog juicer, reverse loop monitor, or a PSX be able to cope with rapid changes in phasing?  I see Dan is thinking of an alternative system but the opto detector seems peferable to me.  Would Dan be able to make the point switch back again with just one detector (after a stipulated delay) or would he need two?

 

Harold.

 

As long as a frog juicer is powered off the DCC bus, or the main rails, the position of the switch rails is irrelevant to the 'direction' the frog is powered for.

[RAF96]

I have toyed with this for a tram runaround and decided that it would depend upon the sprung rate value to work reliably without derails and that an RLM is definitely necessary.

Rob

[Phil S]

If using sprung switch rails - then weighted stock is probably the most important item - all stock including any lightweight trailers / wagons must be able to move the blades without it affecting the momentum as it runs through....

 

Hence the idea of using an optical detector ahead of the point to change it to the required route.

[34theletterbetweenB&D]

It is perfectly possible to make a 'one way' point with no moving parts. Delete the moving blades and guide the wheels by check rails. Most reliable to have the approach to the loop straight ahead, so that the curved route is always taken in the trailing direction. . If the point is tilted slightly to bias to the straight ahead route, that's a further aid to reliability. Since the point will always be taken at line speed, dead crossing should be acceptable

 

I would always prefer this for garden operation as moving mechanisms are easily rendered inoperative by wind blown dirt, bird droppings, ice etc..

[RAF96]

It was suggested to me on forum rather than use a spring that a simple weight pulling on a string attached to the point tie bar was much more reliable and the weight could be adjusted to perfection.

Rob

[Pete the Elaner]

A sprung point will reset itself  after each wheelset passes through it will it not - or at least try to?  In those circumstances, would a frog juicer, reverse loop monitor, or a PSX be able to cope with rapid changes in phasing?  I see Dan is thinking of an alternative system but the opto detector seems peferable to me.  Would Dan be able to make the point switch back again with just one detector (after a stipulated delay) or would he need two?

 

Harold. 

An insulfrog point will not work for this.

An electrofrog point has the frog isolated from the switch rails fairly close to the frog, so the blades & adjacent stock rails are always the same polarity anyway.

I like the idea of a thread & weight to hold the blades over. These will need to be fairly easily moved by a passing train but the weight needs to be enough to hold the blades over at other times. I am thinking that the point blades will need to be very free-moving (& therefore high maintenance) for this to work.

[WIMorrison]

I do like the idea of a little weight hung on a crank or over pulley but you will also need to take out the over-centering spring that is fitted to hold the blades across to make this work. If you don’t do this then you will need a much heavier weight to overcome the effects of the spring and that weight might be too much to allow the blades to move easily.

[Ray H]

Is another option to use the reversing loop for bi-directional movements? The "first" train trails through the points and sets them to the opposite direction to which they were. The second train then traverses the loop in the opposite direction to the first train and trails through the points and sets them to the opposite direction to which they were.