Tender drive pickup

[Ghandi]

Hi all,

 

Following  from another discussion about tender drive locos passing over IRJs, I wondered if anyone knows whether the pickups on such models are always split between loco and tender, or if some have both pick ups within the tender?  Pickups split between loco and tender prevents driving smoothly over IRJs and i was wondering if only having pickups in the tender would get round this problem.

 

Thanks,

G

[The Doc]

As far as I know, all tender drive locos made by Hornby had traction tyres on one side, which by their nature are not good at picking up current.  This means that even the later models (made in China) that had pickups on both sides of the tender would be very unreliable if collecting only from tender.  However, those models also picked up from both sides of the loco, so are unlikely to cause you any problems.  I have a couple of tender drive A3 pacifics from this era and they are very good runners (and, I suspect, will long outlive some of the more recent loco drive models).

 

The ex-Airfix tender drive locos (Dean Goods 0-6-0, Fowler 4F 0-6-0, Fowler 2P 4-4-0) had all pickups in the loco and wouldn't cause you a problem in this respect either.

 

As an aside, I'm a bit surprised that you are having a problem with your tender drive locos running over IRJs - if both of your loops are powered by similar controllers (I saw your track diagram in your other post) and set at the same speed/direction the transition should be smooth.  Might it actually be the points that are causing the problem?  The older Hornby models only tended to pick up from 2 wheels on each side, so when passing over plastic frogs on points they could stutter and stall.

[ColinB]

The later Hornbys had pickups on all wheels including the tender, if it is a 5 pole motor they seem to have pickups on all wheels. I recently converted my A4s by buying the upgrade parts from Peter's Spares, the big issue is getting the wheels as on the A4 the chassis polarity changes so you need insulated wheels on both sides, as you are forced to use the geared wheels on what is now chassis ground. I found a big improvement by getting the loco to pickup on both sides and connecting to the tender with a connector.

[Ghandi]

Thank you for the replies.

 

The issue is definitely to do with the two circuits as the loco has no difficultly over normal points and non-tender drive locos are fine over the IRJs when the direction and speed are matched on the two identical controllers being used.

 

At low speed it is obvious with the tender drive - motion stops as the rear loco wheels leave the first circuit and doesn't resume until the second circuit is completed by the front tender wheels.  Unfortunately this is only achieved with a 'hand of god' manoeuvre, hardly realistic!

 

I wondered if either the loco or tender could be electrically modified to get round this, but I'm yet to find a suitable solution.  Perhaps I'll have to avoid tender drives in future - a shame as much of the second hand market is tender drive and that's where my budget is at!

 

regards,

 

G

[Chrissaf]

Although my preference is to keep the IRJs. Electrically they are optional. You could remove them and re-instate metal joiners to overcome your 'Tender Drive' issue. The downside, is that you will have to more carefully manage how you use the controllers and the point positions.

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Without the IRJs, the transfer of a train across the cross-overs would follow this example methodology. Assuming transferring from the outer to inner loop in this example.

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1. Inner loop controller speed control turned down to zero.
2. Set the point route from outer to inner loop.
3. Use the outer loop controller to drive the train across into the inner loop.
4. Bring the train to a stand-still.
5. Reset the points to their straight ahead position to break the outer to inner loop connection.
6. Now turn up the inner loop controller to resume control of the transferred train.

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What is not particularly realistic about this method is the brief stop you make to the train on other loop before you take control of the train with the second controller.

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Alternatively with practice, as you transfer the train across the cross-over you could start to raise the speed on the inner loop controller and start to drop the speed on the outer loop controller to get a smooth transition from one controller to the other. If you can master this technique, then you can eliminate the need to go through a loco stopped transition in the middle of the overall transfer process.

[ColinB]

 What I did to some of my "tender drive" locos was to add extra pickups in the loco. A standard ringfield motor setup is as you say the loco picks up one side of the supply and the tender the other. To improve things and make the locos run an awful lot better is to put pickups on the other wheels of the loco. On a lot of the 4-4-0 there are already there, on others it means making some pickups. Then connect the loco with the tender by using a connector rather than using the pin bewtween loco and tender. You will be amazed at the difference.

You have to be a bit careful adding the pickups not to cause excess drag, which will cause the loco to slide rather that move normally. I found the easiest solution is to find a pickup plate from the newer Hornby equivalent, then remove the actual copper bit and use glued small rivets to glue it to the plastic part that holds the wheels on. It is fiddly but it works. 

[Ghandi]

That sounds like exactly what I had in mind, however I'm very new to this (only a few months in) and haven't had a body shell off yet, let alone attempted something like that.  I'd have to do some more research before attempting - a disaster would mean the end of 50% of my locos!

[Ghandi]

Following the suggestion by Chrissaf and pressure from my apprentice I have removed the IRJs and the tenderdrive issue is now overcome.  

 

The only thing I now notice is that with the points open, the controllers (R8250) have to be set to different directions (even with one of them set to the off position) otherwise the loco remains stationary, the track buzzes and the controller LED flashes.  Not a huge issue, but I just wondered if anyone knew why and is there a way to rectify this?

 

thanks

[Chrissaf]

That was the reason for including the IRJs to prevent adverse interaction subject to specific controllers. The R8250 controllers are cheap set controllers and have their limitations. Without the IRJs, the outputs of the two controllers will be fighting each other, hence the need to have the direction switches in such a position that the outputs are synchronised.

[96RAF]

Swap two of the feed wires (inner or outer loop it doesn’t matter) over then both controller directional switches will be synchronised.

[ColinB]

OK what are IRJ's?

[Flashbang]

IRJs = Insulated Rail Joiners or Nylon Fishplates. Hornby item R920 Peco SL-11 etc

[Ghandi]

I've now got some going spare if ever you're short

[ColinB]

Oh, now I know what they are, I cannot see the issue. I use electrofrog points so all my points have isolating sections. I never had any issue with my original ringfield motors crossing them and that was before I put extra pickups in the locos. One thing I do do is put microswitches on all my points so if the point is in the right direction the isolating section is powered, if it is not then the loco stops. I use loads of them on my layout, but I have separate feeds to different sections, generally feeding the base of each point.

[Flashbang]

It has nothing to do with the style of points, In fact all Hornby point are Insulated frog! 

What is the problem is that where IRJs are installed in a cross-over pair of points to isolate say inner loop from outer loop any older type of loco using one sides set of front wheels and the opposite sides rear of wheels on the tender as the return will not  be able to connect to the one controllers output, once the one set of wheels are over the IRJs. as the rear set are still on the other controllers feed!

The simplest then is to link out or remove one of the IRJs in the cross over direction rails. But this can only be done if the two loops are feed from totally separate DC controllers which are fed from separate mains power supplies, this then makes the two loops wired as Common return. 

 

The alternative is to not ro install IRJs  in the two cross over rails, but fit one IRJ much further around the inner loop in one rail.

[ColinB]

Oh, now I see. I never had that issue as I designed my own 4 track controller so all the power supplies are internally coupled together so as long as make sure inner and outer loops are set to the same polarity then there is no issue. You would still get the issue whether you were using a ringfield setup or not. As I said with electrofrog points you have to do it as the blade of the point puts a direct short across the turnout not in use.