PF train direction switcher

[Stefx17]

Hello everybody,

this is my first post, welcome to me ;)

First: Sorry for my english.

i got a question:

Thare is a way to switch direction (or maybe stop the train) like the old 4,5v trains?

I got a end of line bumbper, and i need to stop the train or invert direction on it via power function.

Thx everyB in adv

[F0NIX]

Yes it is possible.

You need PF polarity switch: http://www.bricklink.com/catalogItem.asp?P=bb339c01 and you can buy it as a separate part from LEGO with set number 8869 and it is also a part in the "Power Functions Motor Set" 8293

Then you put this between the motor and the PF receiver. You may have to put on a technic axle or some mechanical stuff to get the switch to turn over.

[Stefx17]

All clear, Thx very, much.

Has anyone tried it before?

is It possible to stop the train too?

Any YT video or manual?

[F0NIX]

I have not seen any, but that does not mean it is impossible (also see my signature).

The challenge as I see it is to mount it in a way that does not derail the train. The PF polarity switch is a bit harder to turn than the 4,5v switch. Well, it may be that my 4,5v boxes are well used ;)

I can make a quick test here if you like? I already see different solutions to this.

This is one of the fun thing with LEGO, you can build and test it. If it does not work, you just rebuild it and test until it works :)

[F0NIX]

Well, I just went ahead as I usualy do when an interesting topic with a challenge arrives: I just build a test. And it works! :D

And as I said, the challenge is to mount the switch so the train does not derail or the switch-mount breaks off. Here is a quick and dirty video of the test:

http://youtu.be/HKce17Wszlg

Another thing is speed, too much speed and the train will derail. You may have to set an identical swith on the other side just to balance it out. No need for this to be connected, it may be there only to balance out the force of the thing hitting the switch on one side of the train and pushing it over as the switch come into an angle and are pointing more backwards.

Edited September 30, 2014 by F0NIX

[garethjellis]

This looks like a great solution for a show or something!

[cgarison]

Well that solution is a lot easier than the method that I have been thinking of using which is a Mindstorm Brick with position sensors to send a signal via an IR transmitter to control the train.

[Redimus]

Well that solution is a lot easier than the method that I have been thinking of using which is a Mindstorm Brick with position sensors to send a signal via an IR transmitter to control the train.

I dunno, you're is probably a cleaner approach which means you don't need to build in a big ugly switch that's only of use for exhibitions Also more expensive, so swings and roundabouts..

[F0NIX]

Well that solution is a lot easier than the method that I have been thinking of using which is a Mindstorm Brick with position sensors to send a signal via an IR transmitter to control the train.

What do you mean by "position sensor"? Do you think of using a proximity sensor of some kind? (touch, ultrasound or light is the only ones I know LEGO is making).

See this thread about another system you can use to control many train on the same track and make rules from when a selected train is getting to a selected point on the track. Like shifting only the passenger train into the sidetrack for the station and let the cargo train pass. And all without any train crashing :)

[cgarison]

What do you mean by "position sensor"? Do you think of using a proximity sensor of some kind? (touch, ultrasound or light is the only ones I know LEGO is making).

Depending upon the setup, I would use a light sensor to track position along a track (like a loop) but I might go with a touch sensor if I were using a back and forth shuttle type train on a track that does not loop. I need to give the ultrasound sensor some thought to see if it would work in place of the touch sensor.

[zephyr1934]

Well, I just went ahead as I usualy do when an interesting topic with a challenge arrives: I just build a test. And it works! :D

And as I said, the challenge is to mount the switch so the train does not derail or the switch-mount breaks off. Here is a quick and dirty video of the test:

http://youtu.be/HKce....com/user/f0nix

That's hilarious to see that poor flatcar that once was an HE ping ponging back and forth like that. You did a great job replicating the functionality of the 4.5 v reverser switch.

[F0NIX]

That's hilarious to see that poor flatcar that once was an HE ping ponging back and forth like that. You did a great job replicating the functionality of the 4.5 v reverser switch.

Well, I had just packed down all my trains for a exhibition here in my Town. So I had to make one quickly with the stuff I had left :)

I think that a heavier train will not stop that fast and you either have to go slow or make the stopping mechanism somewhat different than what I did...

The stopping mechanism could be made so that only works in one direction and that they are somewhat spring-loaded sideways so they will give in if the train is coming too fast and cant stop before it has passed the sopping mechanism even if the train motor has reversed its direction. I'll try to test that mechanism I am seeing in my head when I was writing this :)

And the switch on the train can be hidden away underneath the train with some bricks and just leave a small horizontal slot for the arm to come out.