Bachmann Ivatt Cutting Out on Hornby Points

[Flying Pig]

The point design dates from the DC era and routes the power through the point blades so you can, for example, isolate a loco on a siding just by switching the points.  With DCC you often want power to a parked loco for lights and sound, so the clips bypass the switching action of the point blades.

[Dagworth]

On 07/11/2021 at 10:11, Flying Pig said:

 

What's going on with the sawcut through the rails just ahead of the loco in this picture?  That isn't usual for the kind of points you're using. 

There's no saw-cut, the apparent cut is an optical illusion and it's the lifeguard on the front of the loco.

 

Andi

[latestarter]

11 hours ago, Richard Croft said:

It might be worth just fitting a stay alive, it would stop it stalling, I often fit them to locos where pickups can be an issue.

 

Richard

Thanks for all the help on this guys. @Richard Croft I was reading about stay alives in BRM yesterday, but currently (pun intended) I have no idea where to get one and how to fit it. I doubt the only dealer in Ireland has them (I'll check) and items from Hattons are going missing in the post - which may be the case with all UK deliveries to Ireland at the moment.

[Nick Holliday]

On 06/11/2021 at 15:52, Butler Henderson said:

Have you checked all pick ups are correctly aligned? Could be that the plastic frog is slightly raised lifting the front driving wheel off the metal rail and also possibly the centre one as well.

Re-reading this thread, I am convinced that @Butler Hendersonhas hit the nail on the head.  I am convinced that it has nothing to do with the wiring of the point, as other locos are quite happy to run through this one, and all the others on the layout.  Also, I realise now that the problem is that the loco is just stopping, and not tripping the short-circuit function of the DCC system, otherwise other locos would come to a stop at the same time.

I think we have been bamboozled by the concentration of ideas on the pony truck and its wheels, whereas I think the real problem lies with the first driving wheel.  As can be seen in the initial photos, the loco seems to have stopped just as the front driving wheel is hitting the plastic frog.  If the frog is slightly high it will lift that wheel, and, as the frog is plastic, there will be no current picked up by that wheel.  @latestarterhas already noted that the rear current collector doesn't really work, so the loco is relying on the wipers on only the front two pair of driving wheels. Since the loco appears to run happily over certain other dead-frog points, we must assume that the second pair of wipers is working, otherwise it would be stalling at every point, so the conclusion would seem to be that the plastic frog is lifting the front wheel, causing the second wheel to lift enough to stop making electrical contact, resulting in a stall. If I am right, it should be curable by filing down the plastic to the level of the rails, but it would be wise to fix the rear pick-ups anyway, to ensure better running.

[latestarter]

1 hour ago, Nick Holliday said:

Re-reading this thread, I am convinced that @Butler Hendersonhas hit the nail on the head.  I am convinced that it has nothing to do with the wiring of the point, as other locos are quite happy to run through this one, and all the others on the layout.  Also, I realise now that the problem is that the loco is just stopping, and not tripping the short-circuit function of the DCC system, otherwise other locos would come to a stop at the same time. I think we have been bamboozled by the concentration of ideas on the pony truck and its wheels, whereas I think the real problem lies with the first driving wheel. 

Thank you @Nick Holliday for your additional thoughts on this issue and to @Butler Henderson and others for your efforts in trying to solve the problem.

I had a careful look, and can see that the front driving wheels are stopping dead on the 2 gaps of plastic between the metal wings on either side of the frog and the continuance of the rails to the end of the points (see photos). I have filed down the frog, and the plastic in the gaps (the 2nd photo only shows the frog after filing).

The Ivatt will pass over those points at the 4th acceleration mark (11 o'clock) on the Select controller, and slower and it stops, but will move again with a gentle push, even at dead slow. It passes over all other points with no issues. Should I continue to file the gap and/or raise the metal on the wings on either side of a frog a bit, perhaps?

Thanks again for this and any additional thoughts. I'm learning a lot!

Edited November 11, 2021 by latestarter

[latestarter]

@Nick Holliday @Butler Henderson SOLVED IT! Or at least you have! I filed down the plastic in the gap a bit more and now the Ivatt passes over the points at the 2nd mark on the controller (forwards and backwards) - and that is very slow. Certainly slow enough to make me think I've got a very usable loco. 

I made a short video: See it at this link Thanks again for all your help.

 

Edited November 11, 2021 by latestarter

[Butler Henderson]

Glad you have got it running but those rear pickups should still need be sorted

[latestarter]

1 hour ago, Butler Henderson said:

Glad you have got it running but those rear pickups should still need be sorted

 

I am sure you are dead right. I didn't have much luck getting to the wheels from underneath. I might try again tomorrow. Thanks again for your input.