Lighted coach circumventing siding isolating section

[ikcdab]

Hi there, I have a bay platform with an isolation section at the end.  This is conventional: one rail is broken and I have a on/off switch wired across it.

 

I also have a Bachmann 4-tc set. This has coach lighting and through wiring such that it picks up from all wheels and the four coaches are electrically linked together. 

 

What I now find is that when the unit is stood partially over the isolating break, even with the section switch off, the locomotive is not being isolated.  What seems to be happening is that the 4-tc is conducting current through its wheels and thus negating the isolation break. 

 

I don't want to modify the 4-tc.  Is there anything I can do?

I could break both rails, but I'm not sure that will make any difference. 

 

Any ideas?

 

Ian

 

 

[Derekl]

Breaking both rails won't help, since the 4TC will conduct through either rail. You will need to move the break to a position just behind the loco and ahead of the 4TC, so that it doesn't bridge the gap.

[ikcdab]

24 minutes ago, Derekl said:

Breaking both rails won't help, since the 4TC will conduct through either rail. You will need to move the break to a position just behind the loco and ahead of the 4TC, so that it doesn't bridge the gap.

Thanks for the reply. I feared as much. The 4-tc doesnt get sole use of the bay and the isolating break is situated to accommodate other users, so moving it isn't desirable. I now attach a diagram, but i can't see any options.

 

[Titan]

Is pulling up short so that the break is between the loco and 4TC an option? Place an appropriate figure on the platform to mark where the break is, or if that is inconvenient opposite the end of one of the coaches such that when it lines up there the break is not bridged.  Make sure you remember which end of which coach though or you might crash the buffers...  Of course it does not have to be a figure, any sort of platform paraphernalia that you can place inconspicuously as a mark will do.

[BoD]

I appreciate that you don’t what to significantly modify the 4TC but  how much of it is ‘bridging the gap’?  If it is just one set of wheels or one bogie could you somehow isolate those pickups.  You say it has pickups on all other wheels and, after all, pickups get ‘isolated’ all the time when we don’t want them too. 

[ikcdab]

Thanks for the replies that are very pragmatic.

I was hoping there might be a solution with diodes, capacitors and transistors etc that might, in a certain configuration, do the trick!

Ian

[Butler Henderson]

If pulling up short is not practicable as suggested by Titan then a solution is to add an extra isolated section running from the one your have to the end of length of the 4-TC.

[Trog]

How about having two rail gaps with the second gap placed for the 4TC with a switch that bridges it for the other occupants, so the length of the isolated section can be extended or shortened at need.

[5BarVT]

22 minutes ago, Trog said:

How about having two rail gaps with the second gap placed for the 4TC with a switch that bridges it for the other occupants, so the length of the isolated section can be extended or shortened at need.

That’s the easiest and simplest solution.

Paul.

[Flying Pig]

Why do you need to isolate the loco?  Is something else using the bay while the loco + 4TC are standing in it? 

[ikcdab]

44 minutes ago, Flying Pig said:

Why do you need to isolate the loco?  Is something else using the bay while the loco + 4TC are standing in it? 

yes.  Like most layouts, we are short of space and so the bay platform has permissive working. The push-pull can sit there while another working or shunting move occupies the outer end. 

Having written it like that, it seems that adding in an additional isolating section further down the platform is possibly the way to go.

Ian

[Flying Pig]

6 minutes ago, ikcdab said:

yes.  Like most layouts, we are short of space and so the bay platform has permissive working. The push-pull can sit there while another working or shunting move occupies the outer end. 

Having written it like that, it seems that adding in an additional isolating section further down the platform is possibly the way to go.

Ian

 

Isolating the entire train will also prevent the 4TC's lighting from responding to another train arriving, which must look a bit odd. 

[Trog]

Could you control the extra section of 4TC isolation with a gap fitted with a magnet controlled reed switch? Then attach a magnet to the underside of the 4TC so that it isolates the extra section from the rest of the layout when stopped in its stabled position. I assume the internal wiring of the 4TC would then couple the extra isolated section to the main bay platform isolated section, but turning off the power to the main isolated section would also de-energise the extra section as there would be no power for the 4TC to transmit.

 

If anything not magnet fitted was stabled in the bay platform the reed switch would stay in the on position, and turning off the main isolated section would then not affect the extra isolating section needed only by the 4TC.

[RAF96]

Replace the switch with a diode, such that until the polarity is reversed to drive the unit back out no current can pass.

[DCB]

An extra isolated section the length of the 4TC plus loco sounds sensible.  The diode idea is sort of OK when you want to ensure trains stop before buffers when you can't see them.  But you can't leave the loco at the platform end while you pull the stock off with that system.  I have two isolated sections on one platform to allow two local trains to stack.  and for the last foot to be isolated when I'm operating from the other end of the shed and can't see where the loco is vis a vis the buffers.  Tender pick ups bridging isolators drive me mad so I remove them.