I have a swing down section that is unpowered and I need to get power across the section. I’ve been considering micro switchs to connect each part of the layout to the drop-down. I think I have it figured out, but I’d input about exactly how to do it and what is the best kind to use.
For what you’re describing, you don’t need any microswitches. If you want power to the “bridge”, connect each rail on that section to the track leading up to the hinge, using a flexible connection.
If you also need an electrical jumper, via the bridge, to power the other side, you will need to add electrical contacts. I’ve done that on my layout that has 4 lift-out sections for door and window access. I used brass strips, positioned on the bottom of the lift-out, and on the top of the lift-out support. I don’t remove them very often.
If I were to have to open and close them more frequently, I think I would change to what’s called “wiping” contacts, where the metal slides mostly, instead of just plopping down. This makes the contacts sort of self-cleaning.
I’m not thinking of any off-the-shelf easy solution for the contacts–I think you’ll have to make your own.
You CAN get fancier with automatic cutoffs so a train doesn’t run through an open bridge, but you didn’t ask that.
Ed
Many many years ago I had a lift up section that I used a switch to drop power to the track a couple of feet before the big drop. Any micro switch would work, in my case I needed to drop the power to two tracks so I had the switch pull in a 4PST relay that dropped power to all four rails when the bridge was up. Never had any thing take the big drop.
They make several versions of micro switches, some no activating lever some with long and some with short levers as well as some with rollers. Most are 3 to 6 amp rated.
Mel
Modeling the early to mid 1950s SP in HO scale since 1951
My Model Railroad
http://melvineperry.blogspot.com/
Bakersfield, California
Aging is not for wimps.
OP,
A microswitch doesn’t deliver power anywhere, it interrupts power. Wires deliver power.
If you are concerned with delivering power in and around your (“unpowered”) movable section, you need flexible wires and/or electrical contacts.
If you are concerned with interrupting power, as in when the section is not in place, THEN you would use microswitches IN ADDITION to the flexible wires and contacts.
You might want to clarify your needs and goals.
Ed
Ed you’re right. A Normally Closed micro switch will break the circuit when pressed. But if it is wired Normally Open then it would complete the circuit when pressed.
-Matt
Matt,
My point is that you only need a switch if you wish to be able to turn the power off. If you DON’T wish to turn the power off, you DON’T install a switch at all. You just run a wire.
If the OP only wishes to run power to some sections of track that don’t have any (as he stated), then he doesn’t need a switch, micro or otherwise. He needs a wire.
I look forward to his showing up and clearing the air on this.
Ed
The swing up section doesn’t need the power off, the approach tracks do.
The microswitch allows lifting the section to be a one step process. You raise the swing up and power is cut. If you have to do two things, raise it and unplug or turn off a switch, Murphy is always looking over your shoulder.
How far you need to cut power on the approach depends on keep alives and momentum.
I think we all are confused! Which way is this lift-out section swinging? Up, down, or is it being lifted out completely?
-Matt
From the original post:
“I have a swing down section that is UNPOWERED and I need to get POWER across the section.”
(added capitalization).
The above seems to be describing the OP’s problem.
So he needs to get power to the swing down section, because he doesn’t have any right now. I think we all agree that power is useful for running trains.
And it looks like he needs to get power to the “other side” of the swing down section. Also to run trains.
I see nothing there that calls for a micro switch.
I DO see using a flexible connection at the hinge point of the swing down section. Powering the “other side” could be done as I described earlier, or with a simple cord across the gap.
It’s looking like I’m the only one posting who actually read what the OP said.
Ed
Matt,
If you read the original post, you will see him talk about a “swing down section”. Not a “lift-out” section. And presumably it swings DOWN. 'Cause he said so.
Ed
You’d want a device that powered the bridge and "x " inches of approach tracks to each end of the bridge only when the bridge was in place. As the bridge drops down the break in the track should cut the power to those three sections.
Whether a microswitch is the way to achieve this or a regular sized switch depends on the space you have for the switch. There are lots of designs to choose from including a fridge door switch (does the light turn back on when the fridge door fully closes? Who can tell?).
Whether the bridge drops down or lifts up or completely out isn’t particularly relevant to the wiring issue. What’s relevant is killing power far enough ahead of the opening to prevent expensive trips to the floor.
Building the bridge in two lifting sections that hinge upward with each half then blocking the respective approach track might work…
Most or all of us who have responded would want a cut-out for when the bridge was out of alignment.
Possibly that’s what the OP would like, in addition to actually powering the tracks.
I’m sure he’ll show up real soon and fill us in on all this.
Ed
I thought it was clear that I need to get power to a section that has no power when open for in/ out access to the layout. I thought microswitchs could be wired like any contact so that when two were making contact power would move from one to the other. Maybe what I need has already been suggested as a simple metal contact for each rail where they meet when the lift up is closed.
Mike
I thought so too. Although I’ll point out that it also has no power when closed. Clarity, clarity. But then you said the magic word “microswitch”.
Microswitches aren’t contacts. So, no, you can’t do that.
Yup. That’ll transmit power across the chasm. And shut it down when the bridge is out of position.
Thanks for getting back and saying all this.
Ed
I think I have the answer you need. I hope you can understand my sketch.
I had a drop down section for the “Spare Bedroom” layout I built. I later removed it and made the layout point-to-point.
Anyway, the drop bridge section is shown in the drawing. It was supported by two door hinges. The hinge on the right had a removable pin. When the pin was pulled out, the bridge would drop down out of the way.
The red and blue wires show the power bus for the track. The bridge itself is unswitched. It can have power in the down position to no effect. There is no reason to disconnect power from the actual bridge section.
The microswitch controls about 12 inches of track on either side of the bridge. When the bridge is down, one rail is disconnected from the circuit so the train will not move through it and crash to the floor. One microswitch can be used to control the approach tracks on both sides of the bridge.
The gray block on the bridge contacts the microswitch when the bridge is in the upper position and closes the connection between the common (C) and normally open (NO) contacts. There is no connection to the normally closed (NC) contact on the microswitch.
The switched wire from the microswitch is shown in orange.
If you click on the image you should get a better view.
I use inexpensive Microswitches From Amazon. These have worked very well for my model railroading needs, and they cost less than 50 cents each.
[img]https://i.imgur.co
On my prior layout, here is what I did.
I decided to add a bridge on a piece of 1/2" plywood to span an aisle. I would call it a “lift out” section, since I designed it to drop into place and then lift it back out when desired rather than duck under it.
To provide power, I added feeder wires to the track on the lift out section. These wires extended to both ends of the lift out section and were screwed into flat brass plates. When the lift out section was dropped into place, there was a matching flat brass plate on the edge of the layout on either side of the aisle. Those two brass plates also had wires screwed into them to provide power from the main buss.
The lift out section was powered in that manner. Worked like a charm.
Rich
Provided that you understand that it should be a spring contact, to assure clean good contact even when old and a bit oxidized. At these voltages having them be ‘wiping’ also (like a pair of copper leaf springs on either side of a blade) may not give advantages over a button with spring behind it (like the center contact in some 12V cigarette-lighter adapters, a potentially useful source of parts) but it would not put force against whatever locking or alignment mechanism you use for the dropdown.
‘Morally’ you treat the track in the bridge as supplied by its own feeder, and that should have its own soldered connection to rails and dedicated wire pair. Whether you interrupt one side of this with a microswitch that opens when the section is not perfectly aligned to Run Trains is an option, and likely electrically better than ‘open contacts’ (the switch likely will have noncorroding hard faces on its enclosed contacts, for starters) and you can make break over very finely adjustable more easily with some types of switch.
On my four lift-out sections, I did exactly what Rich did. Mine are all double track on up to 4-track. I built a shelf on the bottom of each fixed end, and I placed an array of 1/32" x 1/4" strips there. And matching ones on the bottoms of the lift-outs.
I bent the ends “up” slightly to provide spring pressure on the contact surfaces. I’ve had this system up for about 20 years now with no problems. That said, I VERY rarely remove the lift-outs.
For something that was constantly being opened and closed, I think “wiping” contacts would be better. Here’s an example of wiping contacts:
Note that the moving arm wipes the fixed contacts as it closes. This helps keep the contacts clean.
I suppose you could swipe the contacts off of knife switches. I see in photos where some of them have the parts held down by little bolts.
I’d caution that SOME of these knife switches might take more pressure to close than you care for. I doubt you need something heavy duty. You’re not even using the contacts to switch a current.
You could also make your own out of some of that 1/32" x 1/4" brass strip.
It’s certainly true that these contacts could affect the alignment of the drop-down section. You might need alignment pins also, if you don’t have them already.
If you went with the flat contacts, as Rich and I did, the worst case is that you’ll be using your Bright Boy now and then.
Ed
Our club lift bridge locks in place with two metal toolbox latches. One on each side of the bridge. Power is connected through the latches when the bridge is in place and locked. Disconnected when open.
Martin Myers
I started searching around for photos of my setup and finally found them.
The first photo shows the aisle to be spanned by the lift out section, at an angle no less. I used this lift out section as a reversing section to change the direction of changes. I did not originally plan this when I first built the layout. It was an afterthought, so it was not easy to find a way to reverse trains on an existing layout.
The second photo shows the completed lift out section containing a single track bridge. I later converted this setup to a double track bridge.
The third photo shows the metal contact setup on the left side of the lift out section.
The fourth photo shows the right side of the lift out section. I had forgotten that the right side did not have metal contacts. Turned out, I didn’t need them on that side.
Just like Ed, I did not need to remove the lift out section very often. I mostly did so when I had to work on the far side of the layout and I got tired of ducking under the liftout. Also, when my young grandson would come over to visit, he would race full speed right under the liftout, causing me a near heart attack. So, I got smart and removed the liftout before he arrived for a visit.
Rich