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Peco Unifrog points


mervyn
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Just a came across a problem with my 0 gauge unifrog point I ran my Dapol Pannier across at a crawl and got a short on the dcc controller ,ran it at a faster pace and no problem ,have run my Ixion loco at really slow speed again no problem but the Dapol Pannier seems to create a short at low speed on the frog  ,anyone else had this problem ?

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I have had similar problems on OO/HO insufrog points

The 2 rails past the frog are very close together & a wheel can short across the gap.

If the pic below is the point you are having trouble with, the red line shows the path of the wheel & the arrow shows where a short can occur.

 

408185181_Oscaleshort.png.f30ec3c4dae433bfc374afe7cd1ebaaa.png

 

Wheels with conical cross section are less likely to cause shorts like these than cylindrical cross section

 

John

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On 01/03/2019 at 23:57, Chamby said:

My own experience with the unifrog, after an initial enthusiasm for the OO bullhead points, has been more disappointing.  There is a critical design difference compared to the electrofrog, in that the electrical break between the frog and switch blades are right at the frog throat, whereas the electrofrog has the breaks further down the switchblade.  

 

IMG_2807.jpg.4f3514571aa02f99cd88e07cc1f55941.jpg

 

The consequence of this unifrog arrangement is that a short can occur when the back of a wheel momentarily touches the opposite polarity switch rail next to the frog, particularly when traversing the curved road.  This might be the reason why the OP’s 08 stutters on the point, rather than being due to a dead frog.

 

It is therefore more critical with unifrog points to ensure that wheel back-to-backs are correct, a common issue with some OO RTR stock.  Also, if you run locomotives with dual-pivot pony trucks, such as the Hornby L1, O1, P2 etc, a similar shorting will occur due to the unnatural angle of the pony truck on curves.  A third reason for shorting can be with long wheelbase locomotives, I have surprisingly experienced this with some Pacifics and Co-Co’s.  A click, spark and stall...  it is obvious when and where it happens, when you know where to look. 

 

I have recently decided to modify all my unifrog points by relocating the electrical break farther down the switch blade.  This is not an easy task when the track is already laid and ballasted, but it does cure the problem 100%.  Five done so far, another nine to go...  

 

My advice would be to steer clear of the unifrog if you are ambivalent about which track system to use.

 

The above entry is on a related thread (in layout design section).  First thing to do is check the back-to-back measurements, that will fix the problem in most cases.

 

In trying to keep the electrically switched part of the frog as small as possible, Peco have introduced this design flaw, unfortunately.  It would have been SO much better if they had stuck with the electrofrog design...

Edited by Chamby
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  • 5 years later...

I have just become the victim of the unifrog design flaw point having just laid and wired up 19 points to find my finescale loco won't get across the frog despite being wired via the point motor!?, I am bloody livid, now I've got to rip them all up at great expense, and at £35 a pop not a cheap exercise!!, bloody peco should have a product recall, and reimburse people who waited for these revolutionary points which are rubbish!!

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5 minutes ago, Paul the painter said:

I have just become the victim of the unifrog design flaw point having just laid and wired up 19 points to find my finescale loco won't get across the frog despite being wired via the point motor!?, I am bloody livid, now I've got to rip them all up at great expense, and at £35 a pop not a cheap exercise!!, bloody peco should have a product recall, and reimburse people who waited for these revolutionary points which are rubbish!!

What scale are you working in?

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On 19/03/2019 at 10:59, Chamby said:

 

The above entry is on a related thread (in layout design section).  First thing to do is check the back-to-back measurements, that will fix the problem in most cases.

 

In trying to keep the electrically switched part of the frog as small as possible, Peco have introduced this design flaw, unfortunately.  It would have been SO much better if they had stuck with the electrofrog design...

I think they've tried to make Unifrogs which will satisfy anybody - but if you are going to wire the frogs (which I do) you don't care about the length of the frog "dead section..but you do care about shorts caused by wide wheels on very tight clearances on the separation between polarities...

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11 minutes ago, Paul the painter said:

I have just become the victim of the unifrog design flaw point having just laid and wired up 19 points to find my finescale loco won't get across the frog despite being wired via the point motor!?, I am bloody livid, now I've got to rip them all up at great expense, and at £35 a pop not a cheap exercise!!, bloody peco should have a product recall, and reimburse people who waited for these revolutionary points which are rubbish!!

Hi Paul,

 

I understand the emotion but when you have a clearer head please explain here exactly what the problem is and somebody might be able to suggest a solution that saves you from ripping everything up.

 

Phil

 

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Yeah sorry about the negative post but started questioning my own wiring skills  thinking it's got to be me wiring a polarity switch on my point motors wrong but I did them religiously one at a time and per the diagram on the back of the unifrog point packaging??, seeing I'm test running a loco with triple wheels etc, it's a bit hit and miss across the frogs sometimes the loco makes it sometimes not ,what I've noticed is the one bogie will make it across, the other bogie I noticed a spark, but the loco continues I suspect on the stay alive for a few seconds then stops and my lenz system flashing off?,so what do you think is my first problem solving task is?

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1 hour ago, Paul the painter said:

I'm working in oo gauge 14. 6 mm I think??, standard rtr locos

 

I think that you mean 16.5mm.

 

Sounds like a short - what's the loco and have you checked the back-to- back of its wheelsets?

 

CJI.

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Are you using kadee couplings?  If so, check the length of the tails, they can cause a short if they touch the rails…

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On 23/07/2024 at 23:06, Paul the painter said:

The locos a rtr accurascale diesel

I have some medium BHs and an  A37(with sound)  - I will endeavour to get both in the same place over the next few days - I'm pretty sure I've run the 37 over large BH turnouts with no problems.

Chris

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I've had my layout set up and successfully run my AS Railfreight 37 with sound through both left and right medium BH points without any unfortunate consequences - no shorts or sparking.

FYI I am using DCC with frog juicers rather than switches on my point motors - but that shouldn't make any difference - the frogs are live.

B2Bs vary between 14.55 and 14.6mm.

Chris H

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On 23/07/2024 at 21:37, Paul the painter said:

Yeah sorry about the negative post but started questioning my own wiring skills  thinking it's got to be me wiring a polarity switch on my point motors wrong but I did them religiously one at a time and per the diagram on the back of the unifrog point packaging??, seeing I'm test running a loco with triple wheels etc, it's a bit hit and miss across the frogs sometimes the loco makes it sometimes not ,what I've noticed is the one bogie will make it across, the other bogie I noticed a spark, but the loco continues I suspect on the stay alive for a few seconds then stops and my lenz system flashing off?,so what do you think is my first problem solving task is?

Can you disconnect the frogs and see if you get the same issue?

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