NEED A RELIABLE MECHANICAL CONNECTION BETWEEN TURNOUT & FROG POLARITY SWITCH

[colinglenister]

I'm about to lay my track. But before installing point motors I want to get the track laid and connectivity tested. To this end i will just manually switch my turnouts during the tests.

The problem is, I need a temporary, reliable, simple mechanical method of connecting the tie-bar (point blades?) to a microswitch or similar for switching the turnout frog polarity.

There must be hundreds of such methods and I don't want to 'reinvent the wheel'.

Any suggestions please?

[nigelcliffe]

Must be dozens of methods....

a) (For DCC), just use devices called "frog juicers" and you're done. That works at testing, works when finished. But not everyone is totally sold on the concept (I'm a bit sceptical).

b) if under-baseboard tiebars exist for your turnouts, then pretty simple to arrange a microswitch to move as tiebar is moved. Sometimes placing switch with a roller that engages/disengages in a notch in the tie bar can be easier to adjust for movement.

c) (left for next person to add c, d, e, etc..).

[colinglenister]

Tie-bars are above baseboard.. microswitch or similar below baseboard.

[Philip Hall]

IMG_1238.jpg close.jpg

I like microswitches, as they are very reliable, enclosed etc. However, for my storage yard tracks, which are all controlled and switched on the surface, I have used some small DPDT slider switches with the associated rodding inserted into a small hole in the switch. The advantage of the DPDT switch is that if one side of the switch should fail, the other side can be easily wired in, as there are three contacts each side of the switch, concealed by a white cover plate. I have no idea where I got the switches, I just found them in a box, the advantage of hoarding for twenty - odd years!

Philip

[grovenor-2685]

Tie-bars are above baseboard.. microswitch or similar below baseboard.

To my mind devising and fitting tempoary linkages between tiebars above board and microswitches below is just a waste of time for such testing. Why not just use SPDT switches, eg those shown by Philip in some convenient spot where you can switch them when setting the points?

[jon price]

Yeh, I'm in a grumpy mood after meeting a young girl who is sleeping on the streets. But lets not do politics, lets do simple politeness. If someone wants to switch frog polarity, and I do as well, they don't want some smatarse reply about RC control of locos. Can we just be reasonable here instead please? It might be funny when you start to type it but it is just irritating when you have finished.
The offending off-topic diversion has been moved to https://www.scalefour.org/forum/viewtopic.php?f=137&t=7940. IMHO it was too far removed from this subject. Keith

[John Donnelly]

a) (For DCC), just use devices called "frog juicers" and you're done. That works at testing, works when finished. But not everyone is totally sold on the concept (I'm a bit sceptical).

I'm using juicers on South Pelaw and, so far so good, although part of me does think it counter intuitive to allow a short albeit one that is 'handled' before the DCC system can react...

[Winander]

I'm using juicers on South Pelaw and, so far so good, although part of me does think it counter intuitive to allow a short albeit one that is 'handled' before the DCC system can react...

I have joined the sceptics as if there is a short, then it surely arcs somewhere. They are also expensive when compared to a microswitch or a relay.

I would recommend switches for testing, reliable and simple.

[Tim V]

Cheap and reliable?

I just run a wire from the crossing, which can be looped around or tucked under the appropriate rail for the polarity I want. That wire can then be attached to the proper switch - when it gets put in. For testing purposes - this is enough.

[John Donnelly]

I have joined the sceptics as if there is a short, then it surely arcs somewhere. They are also expensive when compared to a microswitch or a relay.

If they become unreliable then I'll change to microswitches but the one advantage that they do have is never needing adjustments unlike my experience of microswitches.

[davebradwell]

It depends what you call a test - surely the mechanism that drives the point tiebar and works the switch is one of the essential items on the list. Anyway, I've come to the conclusion that the only way to test a layout is to run a complete sequence of trains. That's when you discover the need to propel a double length train through your tightest pointwork. Random trains are no good at all.

Quickest way for a quick try-out is just to stand a block of metal on the wrong road.

Yes, setting microswitches is difficult. We did it with an appropriate feeler gauge at work many years ago before I designed them out but only certain types were manufactured such that this was possible - the switching position varied too much on most. I still feel that Frog-juicers are unethical in some way - it just seems wrong to create a short but I have to admit to their apparent reliability.

DaveB

[martin goodall]

To my mind devising and fitting tempoary linkages between tiebars above board and microswitches below is just a wste of time for such testing. Why not just use SPDT switches, eg those shown by Philip in some convenient spot where you can switch them when setting the points?

That's the method I used originally for temporary polarity switching - a temporary panel of SPST switches. When under-baseboard mechanical turnout operating mechanisms were later permanently installed, I then fitted micro-switches instead, driven off the under-baseboard point rodding.

(I never had a problem with adjusting these. An omega loop or Z-bend in the rodding/operating wire gives positive movement which changes the micro-switches reliably every time.)

[colinglenister]

depends what you call a test - surely the mechanism that drives the point tiebar and works the switch is one of the essential items on the list. Anyway, I've come to the conclusion that the only way to test a layout is to run a complete sequence of trains. That's when you discover the need to propel a double length train through your tightest pointwork. Random trains are no good at all.

Dave, that's exactly what i intend to do.. But i don't want to have to switch the frog polarity separately by hand. I want the tie-bar/switch blade to set the required frog polarity automatically with a switch. Sooooo.....

What cheap, reliable methods have been used in the past to mechanically link the tie-bar to the microswitch (or other switch).

[grovenor-2685]

Not something I have ever done, I install the point operating system before such tests.
Either model aircraft style rodding with microswitches as recently illustrated in Julian's topic or point motors with associated relays when electrically operated.

[Philip Hall]

What cheap, reliable methods have been used in the past to mechanically link the tie-bar to the microswitch (or other switch).

If I were linking the tie bar to under or over baseboard rodding, I would arrange a simple rod or bar protrusion from the rodding which simply depresses the spring arm in the micro switch. I did this on my old Taw Vale layout, we never had a failure and it was extremely easy to adjust by bending the protrusion. MRJ 53 carried an article on the installation.

On my layout on the 'visible' side, the turnouts will be connected via wire-in-tube, on the surface again, to some very old Hambling's Addalever frames. The levers on these have a linking bar/rod attached to the bottom of the lever which allows a straight pull-push where the wire is attached, and on these I will solder another piece of rod (just as above) which depresses the arm in the switch. Wires will then run to the turnout along the path of the wire-in-tube to the relative rails.

I don't have pictures of this part of the layout yet as we haven't got that far with tracklaying. These methods are truly antique stuff but being mechanical should be very reliable. Once covered up with ballast and scenery they have to be.

Philip

[nigelcliffe]

I have joined the sceptics as if there is a short, then it surely arcs somewhere. They are also expensive when compared to a microswitch or a relay.

If they become unreliable then I'll change to microswitches but the one advantage that they do have is never needing adjustments unlike my experience of microswitches.

Frog Juicers are unlikely to become unreliable, the electronics should be fine.
The sceptical questions about them is around whether it is good design to have a control device which requires a short (error condition) to occur to operate. And then whether that short will lead to (small) arcing of wheel to rail, which in turn might be damaging the rail or wheel surfaces.

I'm sceptical about them, but don't have anything doing enough miles to give any indication whether the concerns are a reality, and whether that reality happens in any reasonable operating life of a locomotive or layout. There are alternatives which don't have those risks.

Microswitch problems are usually because people are trying to operate them over very small distances. Used in mechanically sound ways they work fine.

- Nigel

[davebradwell]

Isn't this just Catch22? The most reliable method is to drive the switch from the actuating mechanism (which you don't want to install) rather than the tiebar which has less movement and will tend to be pushed open at one end by the spring in the switch.

DaveB

[jon price]

I notice that the Tam Valley Frog Juicer for six turnouts is just under £70, and the Gaugemaster DCC80 DCC Autofrog in a pack of three is just under £18. So using the Guagemaster units for six turnouts would be half the cost of the Frog Juicer, and for between six and eleven turnouts (I have eight) quite a lot cheaper.

Anyone got experience with the Gaugemaster units?

[John Donnelly]

Anyone got experience with the Gaugemaster units?

They are the ones that I'm using. As the layout is still at the track laying stage, I've only installed about six of them but they have proved to be completely reliable in testing so far.

[Martin Wynne]

If they become unreliable then I'll change to microswitches but the one advantage that they do have is never needing adjustments unlike my experience of microswitches.

The fitting and maintaining in adjustment of microswitches is a cruel punishment in contravention of the Geneva Convention.

For polarity switching you consider all the options, weigh up all the pros and cons, and then, like always batting first, decide to use relays. Or just decide to use relays anyway. Foolproof, last a lifetime, nothing to adjust or go wrong, fit and forget with a dab from the glue gun anywhere convenient, and cost no more than microswitches - 20 for £13.99:

https://www.amazon.co.uk/sourcing-JQC-3 ... B07JG4ZT4S

For temporary testing, just switch them on and off by connecting to 12v with paper clips.

cheers,

Martin.

[Porcy Mane]

Going back to post one, it might have be easier to narrow down suggestions for a "reliable mechanical connection between turnout & frog polarity switch" if we knew what type of tie bar is being used. Is it the sleeper type, the Masokits/Ambis etched fabricated type, or one of the many other t.o.u's that is available?

I need a temporary, reliable, simple mechanical method of connecting the tie-bar (point blades?) to a microswitch or similar for switching the turnout frog polarity.

From subsequent posts I assume you will be testing the turnouts/track work in situ as opposed bench testing and alongside electrical testing you want to mechanically test the turnouts by running trains through them at the same time? Is that correct?

For electrical testing a simple multi-meter should be good enough for testing insulation & continuity of the turnout.
If you are wanting to check frog switching on turnouts individually, you could then possibly use a single mtb MP-1. They are a Czechoslovakian assembled turnout motor that has inbuilt switching operated via a camshaft. They are generally available in the UK.

Connection to existing point-work wiring and operating switch should be simple as they use screw terminals. Firmly holding the motor over the turnout so the operating needle engages through a hole in the tiebar (or an extension to it) shouldn't be difficult.

Here's a video of one I've been playing about with:

https://youtu.be/Sr-s9x21V7A

They use an N20 motor as in the Hornby Peckett. Internally there's not a lot to go wrong with them.

MTB~MP-1-T'out-005-EditSm.jpg

A link to their website: https://mtb-model.com/pages/prestavniky.php?lang=en

The manual:

MP1-setup_CZ_EN_DE.pdf

Apologies if I've missed it elsewhere but is your layout to be DCC controlled or conventional DC. If it's DC that prevents the use of Juicers. I'm with Dave in feeling uneasy with something that uses a fault condition to switch polarity. It just seems intrinsically wrong. That's not to say I haven't used them and don't understand how they work.

They make track wiring for turntables when using DCC sound an absolute doddle. The Tam Valley juicers that I've used (there's a Brit company now making a similar product) are solid state and using mosfets they do their stuff in less than 300 microseconds so there's no chance of any electrical arcing or anything wearing out.

No track arcing here, should anyone be interested but there is some D.D.T. (decidedly dodgy trackwork!).

https://youtu.be/EpMe119GsM0

The fitting and maintaining in adjustment of microswitches is a cruel punishment in contravention of the Geneva Convention.

I don't think John will mind me saying; experience has made him acutely aware of that.

P

[allanferguson]

All my turnouts are operated by wire in tube connected directly to miniature slide switches (I accept there are other ways of making the mechanical connection). The electrical switching of the crossing is done by the slide switch. This does require more wire, but it does away with the problems of setting up microswitches, and is, in my experience, totally reliable.

Allan F