Zimo Auto Uncouple Feature

[michaelp]

Hello everyone,

after reading an RM web post from 2018 re: Zimo Auto Uncoupling I was wondering if it might work with 'Sprat & Winkle couplings? If anyone has done this I would be interested to hear, I have a look at the Zimo manual which states that CVs 115 and 116 are responsible for the auto uncoupling, is it just a case of assigning these two CVs to the desired function keys? 

As always thanks in advance for any advice.

 

Michael

[Nigelcliffe]

If your coupling needs either step in the "waltz", then the feature will work. 

On the decoder, select a function output not in use for lights or other features(*).  Make that function's output behaviour into "uncoupling".  Allocate a function key to operate that output.  Setup the Waltz movement parameters.    

 

 

Note that there is (was?) an issue with how commands are repeated in NCE controllers which can mean its difficult to stop a loco from moving after the Waltz movement has started  (ie. rather than coming to rest after two small movements, the loco just keeps on moving).   Its to do with the number and nature of function command repeats to the track (a setting inside the NCE system).  Changing that setting inside the NCE system fixes the issue.   (And no I don't know the exact details without reading NCE manuals ). 

 

 

(* unless you've built an on-board mechanism with an electromagnet or similar to operate the coupling, when clearly you need to select that output.  Quite possible to do,  I've had them on small locos in 2mm and 4mm scale for ages, but it gets extremely fiddly to assemble them. ) 

 

 

Nigel

[michaelp]

Hello Nigel,

thanks for your reply, my control system is Lenz 100 and the couplings are attracted to magnets below the ballast. I have been looking through the Zimo manual trying to figure out how to select a function output and make it 'uncoupling' then assign a function key to operate it but I can't make head nor tail of  the manual.

Any further advice/help would be appreciated.

 

Michael

[Nigelcliffe]

Track-side uncoupling magnets, so all the loco does is the back-forwards shuffle to cause uncoupling over a magnet.  You'll have to fine tune the movement to get enough movement (particularly if splitting a train at the rear, where all the slack has to be taken up), but not so much that it looks grossly exaggerated.  Start with lots of movement, then turn it down to what is actually needed. 

 

1 - decide on a function output not in use for something else, such as lights. Doesn't matter what you pick, but need one (can be a "virtual one" on some decoders, because most Zimo's have the same internal code, just lacking the actual output on the smaller ones). 

I'll use FO3 for this example (ie. the fifth output after Front Light, Rear Light, FO1, FO2).  

 

2 - look up default function mapping, which puts FO3 onto key F3.   If you want to change this, alter the function mapping.

 

3 - change the output behaviour ("special effects", manual section 3.22) of FO3,  CV is CV129 (top of page).  Reading down possible values, "uncoupler" is value of 48 (both directions), 49 (forwards only), 50 (reverse only).   Both directions makes more sense, so CV129=48.

 

4 - coupling movement values, CVs 115 and 116, (manual section 3.24). 
CV115 controls the time voltage is applied to the output.  As nothing is actually connected, this may be seen as irrelevant, but the time full power is applied is relevant (or nothing happens according to the manual).  Begin with, by setting a large value for the pull-in time.  Hold current is irrelevant, so leave as zero.  So, start with CV115=90,  I think that will work without any further changes to CV115. 

CV116 is the movement, with units=speed step, tens=time to pull away, and hundreds=backup before moving.  Suggest setting CV116=199 to begin with, then reduce the speed step of the movement (units value) to a sensible speed for the loco, then reduce the tens digit to get the amount of movement required. 

 

 

That should now work with the F3 function key.  Bring loco to a stop pulling a train.  Once stopped (don't change the direction!), turn on F3.  Loco will backup, the pull forwards and finally come to a stop again.  Turn off F3 and drive normally.  

 

( Alternatively, you can use CV116 without the hundreds set in the value.  Then, all you get is movement in one direction, so you need to set the loco into reverse if you want movement backwards, and set the direction to forwards if you want the movement to be forwards ). 

 

Note that the movement is altered by speed table values, and any acceleration/deceleration you have set on the loco,  if you have a half-speed key set that alters things, and if you have a "no momentum" option then that will alter the behaviour.  

 

 

 

Its slightly easier to setup the CV's with DecoderPro, though the features are a little scattered around the DecoderPro user interface for this behaviour.  Or, if you're in the north of Northumberland, arrange to meet up somewhere and I can show how - I live just over the Scottish Border.

 

 

 

- Nigel

 

 

[michaelp]

Nigel,

Thank you for the very detailed reply, I will have a go with this to see if I can get it to work.  I am in South East Northumberland but I would be more than happy to travel to the Borders for a chat.

 

Michael

 

 

[Roger Sunderland]

Hello Michael

 

We use the auto uncoupling feature on Zimo decoders on our exhibition layout Bournemouth West (thread on here). However we use Kadee couplers with a micro actuator made by a Swiss company, Precimodels. The movement forward or reverse, to release tension on the coupling is followed by the hold which holds the jaws of the coupling open whilst the loco reverses. The system is almost a 100% reliable. I have fitted the system to around 10 locos now and Nigel is correct in saying that  the settings for the CVs can depend on how the decoder has been set up. If it's of any help, these are the values I use in the majority of cases.

CV127 = 48   If you want the green wire to operate the uncoupler process ie FO3

CV128 = 48.  If you want brown wire to operate it. Ie FO4

putting a value of 4 in any CV between 35 and 46 will determine which button works the function ie 1 for 35 up to 12 for 46

 

CV 115 = 46 This is the hold power and may not be appropriate for your chosen coupler

CV116 = 179. I find this gives a fairly slow and smooth "shuffle". Again you might want to play with different values in this . The hundreds digit (1) is the back up to unload the coupler. The tens digit (7) is the time taken to back away after disengaging. The ones digit (3) sets the speed of the loco when performing the uncoupling process 3= approx speed step 12.

 

Hope this helps.

 

[wychcan]

I’ve followed the above advice from you all, and success in doing the waltz. 

But I need to ask Nigel about his use of the electromagnet (watched his video) he used. 

 

What volts would it be and did you connect directly to the decoder or via a ‘buck converter’, resistors etc? You can gather I’m not too good with electronics.

 

i have tried a 5 volt electromagnet but my decoder (zimo 645) now reads ‘error 2’ and reset!

 

Any advice would most definitely be much appreciated,

thanks

Nigel 

[Nigelcliffe]

If you dig through my old blog posts (back to 2008 - that long ago!) you'll find more stuff on the electromagnets I've used.

 

Essentially two types: 

• the really small ones are home wound, which is a tricky process requiring a lathe with a very slow bottom speed, the finest winding wire I could find, and small video camera 2inches from the lathe with a monitor to see what I was doing.    These would come in at a fairly low internal resistance (seem to remember 16 ohms), so need something to limit the current through them from the decoder function output (as either the coil will melt or the decoder will over-load).  I used series resistors for the job, they are under specified on wattage (for size reasons), but as only used intermittently I get away with it. 
• slightly bigger are Plantraco Microflight "Nano Actuators", available either from Plantraco in Canada, or possibly from Micro Radio Control in the UK.  They consist of a small and extremely fragile coil (expect to break the wires on more than one, which will render them useless) and two tiny magnets.    They are designed for 5v micro radio control flight use.   So, two in series (both ends of loco) would be 10v rated.  So, taking a bit of a chance on intermittent use, that's OK for a function output.  The current draw is well within a function output's rating for most decoders. 

In both cases, I've set things up so a permanent magnet is repelled by the coil - this overcomes any mechanical "stickiness" at the start of movement.  In my designs, the coupling returns to rest position by gravity - often tiny bits of lead glued to various levers/flaps to create the counterweight if I can't arrange the permanent magnet to be the counterweight itself. 

 

I'd do electromagnet bench tests without a decoder.  Use a decent power supply of 12vDC or more, with enough current that the power supply doesn't limit things. Setup the coil and any associated mechanical or electrical components and test. Measure the voltage, the current drawn and make some estimates of heating in the coil (if it gets hot in 5 seconds, you need to change things!).  I have several cheap multi-meters, and will use them all at once to do these measurements. 
Read the maker's spec sheets for function output currents and arrange enough head-room:  eg. a decoder spec may say 100mA function output, that means 90mA at the coil isn't sensible, but 75mA might be OK.    Only when all is working sanely do I try it on a decoder - usually a cheap old test decoder - and re-check my current, voltage and temperature measurements.   Then use the "real" decoder and repeat.  And finally install into a loco.

 

 

[wychcan]

Nigel 

thank you for taking your time, input and information.

It seems I’ll have to do some more bench work and testing.

Nigel