Tag: 4Dbrix

Automatic LEGO® train decoupling solutions

Post reviewing the different types of automatic decoupling solutions

In order to have an automatic, “no-touch” railroad layout, an automatic decoupler is high on my wish list. I visualize a shunting yard with a ladder, where I can rearrange the consist of freight trains, and have a somewhat prototypical operation.

There are in short 4 types of decouplers that I am aware of:

1 – Decoupler under/between the rails

A beam stretches upwards and catches the undercarriage of the wagon. These solutions rely on the inertia/speed or at least the wheel grip of the locomotive, to overcome the pulling force of the magnets.

  • Pro: The solution can be made very small and compact
  • Con: It will always decouple by the weakest magnet link – so it is mainly useful four decoupling a single wagon or a complete set of i.e. passenger cars.

The solutions can be:

  • Passive: Always decouple when running the train forward over the decoupler. No motorization required!
  • Active: The beam can be raised/lowered, allowing for running on the track in both directions, and actively manage the decoupling.

Examples:

2 – Sidebeams + pushing wagons/magnets from each other

This solution drives a beam in between the wagons you want to decouple, and actively pushes them away from each other, to overcome the magnetic pulling force.

  • Pro: You can decouple anywhere in a trains consist, making it very flexible and more prototypical.
  • Con: Depending on the motors, the build can take up quite some space. The stopping location of the train must be very precise.

As in the first video in examples below, it might be possible to use only one motor to separate the magnets. The video features trains with the old style open magnetic couplers. I will try to check whether it also works with the new style magnets, or if I have to stick with a design, where I am actively pushing the wagons apart. More about that in upcoming post.

Examples:

3 – Blocking wheels of wagons / 4Dbrix

Another way of decoupling is to “lock” the wheels of the wagon, and drive the locomotive away, thereby decoupling. Intuitively, this would give the same problems as with solution 1: The wagons will decouple at the weakest link in the consist. The 3rd party manufacturer, 4Dbrix, however claims that this is not the case.

  • Pro: The smallest footprint on the reviewed solutions.
  • Con: May decouple only at the weakest link of the consist. It is NOT easily operable with Mindstorms, but instead operated by the free nControl PC software by 4Dbrix.

Link to product: https://www.4dbrix.com/products/train/2-04-017-decoupler/

4 – Original LEGO® 12v decoupler

LEGO® made a decoupler for the 12v train era back in the 1980s. It is difficult to get your hands on, and from what I can see from forums etc., it is not 100% reliable.

An idea for the future could be to build a similar solution, where the twisting mechanism is raised up between the tracks.

See a review here https://www.youtube.com/watch?v=EAeQRgs6qCU