An Electric Uncoupler for 00 Gauge (Improved version)

Build an electrically operated uncoupler for 00 gauge.

Following on from the original version of this uncoupler I needed to build 14 of them for use on my layout "Livsey Lane". Having experimented with this new version earlier I decided to standardise on the components and make it easier to set up instead of having to trim the original tubing used.

Parts list for the Uncoupler. (standardised)
1. Piece of Lollipop stick.
2. Brass wood screw 3.5 x 12mm
3. A couple of panel pins
4. Thin walled brass tubing 5/32 x 0.014
5. Off cut from copper strip board or plain paxolin if needs must
6. One of the coils from an old Peco point motor
7. 1 inch x No6 Metal chipboard screw.
8. 6M full nut (for return weight).
9. Four small wood screws (for fixing paxolin to baseboard).
10. Electrical supply of 12 to 18 volts (Ideally Direct current)

View of the uncoupler
Side view of the assembled uncoupler (Track bed omitted for clarity)
Assembly of the device.
Start with the old point motor and carefully dismantle it so that you end up with one of the coils and the short lengths of fine copper wire having been unsoldered from the paxolin / metal terminals.
Cut a square-ish bit of copper strip board and drill one 1/4 inch hole in the centre and four 1/8th inch holes at the corners.
Glue the motor coil to the plain side of the copper stripboard so that the centre is over the 1/4 inch hole. You will find that the plastic case of the coil is a loose fit and I found it best to insert glue into this too.
Push the two copper wire tails through holes in the stripboard and solder each one to a separate track of copper strip.
Solder a pair of wires to the copper strips that you earlier soldered the coil wires to. These will be the feed wires to the unit when it is all fitted in place.
(If you have had to make do with plain paxolin here, then solder some longer thin insulated wires on to the tails and secure to the coil with tape so that they don't get pulled off)
Cut about an inch and a half piece from the Lollipop stick and file or sand the ends round. (One end will already be round)
Drill and countersink a 4mm hole in the centre of the stick so that the brass screw fits flush with the surface.
Offer the stick up to between the track rails where it is going to be used and with the hole for the brass wood screw between two sleepers. mark the stick for two more holes to take the panel pins so that they will also be between sleepers.
Drill fine holes in the stick for the panel pins.
Now drill the centre hole in the track bed ( 1/4 inch) that the lifting tube will pass through and drill the two smaller holes (1/8 inch) in the track bed that will act as guides along with the panel pins.
Insert the panel pins to be flush with the top surface of the stick and insert the brass screw into the counter sunk hole then super glue this in place.
Take the length of brass tube and holding it carefully in a pair of pliers screw the brass wood screw into the end until you have all the thread inside the tube. Use more super glue to lock the screw in place.
You should now have your length of brass tube with the lollipop stick complete with panel pins secured at one end.
Lower the length of tubing into the hole you have drilled in the track bed so that the panel pins also go into the 1/8th inch hole and the lollipop stick is lying flat on the sleepers.
(note:- depending on the thickness of your baseboard you may need to trim the ends off the panel pins to allow the stick to lie flat.)
With the brass tube still in place slide the point motor coil up from underneath and fix in the correct position with the small wood screws.
Check that the tube is an easy sliding fit and falls back readily into its home position against the sleepers. If it doesn't then find where it is binding and clear any tight spots.
Once you are happy that the whole assembly lifts and falls back freely, then with the lollipop stick tight against the sleepers, mark the brass tube for cutting where it is level with the tube in the point motor. (I found a razor saw ideal for this and the subsequent cutting).
Remove the tube and stick assemble from the point motor and cut the tube at the marked point.
Now hold the tube again in large pliers and carefully insert the 1 inch x No6 chipboard screw into the remaining open end of the tube. Screw this in to a little more than 1/2 way then unscrew it completely. You have now cut a thread on the inside of the brass tube that will make the final fixing much easier.
(Note:- it takes considerable force to insert the chipboard screw so hold the unit with the pliers around the brass screw and lay the lifting plate on a flat secure surface so that the tube is vertical. This prevent crushing the tube and allow you to apply pressure on the chipboard screw.)
Insert the assembly into position again on the track and this time place the 6M nut on the chipboard screw before screwing it back into place from underneath.
While doing this hold the top brass screw rigid with one screwdriver and use a second one to drive the chipboard screw in until you have a gap if about 1/4 inch between the nut and the bottom of the point motor coil. You can later adjust this to give you the exact amount of uncoupler lift once you have tested it electrically.


Parts needed for construction

A view of the parts needed to construct the improved version. The two T's shown on the part of the lolipop stick are to denote that this is my "Template" as I had a total of 14 to make for my layout "Livsey Lane"
Click for video
A short video showing the uncoupler working

Operation
Wire the uncoupler to the power supply (I use my souped up CDU for this which unlike the proprietary versions gives a continuous DC output after the initial kick from the capacitor) via a push button on your control panel.
Push the button and the chipboard screw is drawn into the coil thus lifting the stick and the coupling hooks of your stock that are parked over it. Simply drive the train away while holding the button down and the stock will part.
Do not keep the button held any longer than you need to as the coil will get warm and could be damaged if power is supplied to it for a long time.
Note. You can adjust the amount of lift given by simply screwing the chipboard screw in or out a turn or two.

John Essex Heywood Model Railway Group

This page updated 31st March 2013