On-Contact Connect/Disconnect Needed

Why not just wire a feed to the track on the bridge and connect it to the two sides of the bridge fixed tracks?  No need to actually make the physical tracks connect, right?

If you mean that you have a bridge that lifts out entirely, and is then lowered into position, you could use gravity and have the pointy ends of bronze nails (wired to the bridge track section) on the under side of the bridge, that come into contact with 1" by 1" bronze plates on the surface of the bridge supports (wired into the main track supply). You could make a little "shelf" at both ends, from a piece of 2 x 4 lumber, that the bridge sits on, and where the contact plates are mounted.

Is there a reason that you don't want to have a cord that requires a manual connection? It would seem more prudent to have a system that requires a manual act to make the connection, to ensure that everything is ready to roll, before jeopardizing the little people on your trains.

A cord can have a couple of extra leads, wired through a loop connection on the bridge, that activate a fail-safe relay, which cuts off track power in advance of the bridge a few feet in both directions if the bridge is out.

Thanks for the replies.  Construction is as follows:  The bridge sits on 2 parallel wood girders about 4.5 inches apart, joined by several cross pieces.  The structure opens in the up direction at one end.  The other end (approx 4 inches from the end) has a threaded rod inserted through it, on which it pivots.  This way, as one end raises, the other end drops.  As a result I avoid all of the issues caused by using hinges such as binding of the track, hiding the hinges, etc.  The Atlas bridge sits on top of the structure, making the structure visible only from the sides.

I have connected hot and ground wires to both tracks on the bridge, and if I can't find a better alternative, will leave enough slack to connect them to the permanent track on the layout at the end of the structure which drops.

I would prefer to rig something at the end that raises, which would connect upon contact when the structure is lowered into the closed position.

Phil

Well, I think it would help to actually see the bridge to figure out what would work in your specific situation.  I think I'd be happy with just wiring the bridge tracks directly and working out a way to hide the wires.

The best thing to use would be a metal topped heavy duty momentary switch.
That way when the weight was lifted it would kill the track power and alignment wouldn't be a problem . I'd be easy to make a height adjustable plate so you can get it adjusted just right.

David

I like the switch to kill track power to the bridge when it's up, didn't think of that.

Phil:

When designing my new layout last year I realized that the duck under that I planned could be replaced by lift out bridges. On a previous layout I used magnetic cabinet latches to provide power to the bridge when in place and also add stability to the bridge. It works great!

This is a photo of the underside of the single track bridge (upper level) showing the

strick plate that is wired to the track outside rail. There is another at the other end wired to the center rail.

Both the lower (3 track) and upper single track lift out bridges are wired the same way using magnetic latches for power to the bridge, as well as lever switches that serve to kill power to approach tracks when the bridge is out.

Here's the end of the bridge support showing the magnet in place (wired for outside rail power) and the lever switch that is "open" when the bridge is out thus cutting power to approach tracks. The other end of the bridge is wired the same, but the magnetic latch provides power to the center rail of the bridge.

I have found this method to be very reliable and simple to use, as I often remove the bridges to access the inside portion of my layout.

Stan

Use the micro switch as shown in the picture. Use it to power a relay coil with the number of contacts to suit your needs. For track power run a flexible wire to the track from a stationary point.l

Dont try to run a lot of amperage through a micro switch.

Dale H 

The micro switch I used is: Philmore Mini-Snap Action Switch #30-2020 SPDT rated 15A - 125/250V AC. With this rating, I am not using relays which makes things much simpler.

Stan

Thanks, guys for the responses.  I also like the idea of killing the track power on either side of the bridge when it is in the up position.

I'm going to pore through my AllElectronics and Mauser catalogs for switches.

Phil

Phil,
If you have an electrical supply house nearby that handles Allen-Bradley or Hubble
They should have the switch I was talking about.Something in the 20 amp range should be okay.
If you do use a micro style switch as depicted in those pictures I highly recommend you use one with a roller on the end so you don't have any binding

David