Turnout motor melt down

Discussion in 'FAQs' started by green_elite_cab, Oct 15, 2006.

  1. green_elite_cab

    green_elite_cab Keep It Moving!


    this is the second time in a year that that one of my atlas switch motors burned out on me and melted through the plastic. luckily for me, i had just bought a replacement turnout for the other side of that crossover, so I had a spare switch motor to keep the trains running. However, this is bothering me.

    This time i think something might have been leeaning on the button, but it made no buzzing, it just started smelling and before i knew, i looked around and found it melted.

    this happpened to me a year ago except the whole control panel was un cluttered, and i don't know why it melted.

    Are these atlas switch machines bad for business reliability wise? Right now i don't mind them sitting unrealistically on my track, but if these things are going to be over heating and causing more damage then i might go with under table switch machinces.

    speaking of wich, are they hard to install if there is already ballast? or can i drill in from the bottom?

    thanks, Chris
  2. R. MARTIN

    R. MARTIN Member

    It's been years but once upon a time I used Atlas products when modeling in N-scale. At that time the problem of melting switch motors was in the electrical switch and not in the coil itself. The switch looks like it's in the right position but the contacts are still touching inside causing a heat build-up. I think you need to look into a better type of switch and replace all of the Atlas ones. Try an electronic store in your area. Good Luck to you.
  3. pgandw

    pgandw Active Member

    I recommend building and installing a Capacitive Discharge (CD) power supply for your turnouts. You can buy a commercial unit from Circuitron or make your own. Parts are less than $20 even when bought at Radio Shark, and the circuits are quite simple. Here is a link for some CD circuits of various complexity: http://home.cogeco.ca/~rpaisley4/CDPSU.html

    If you are using the Atlas control switches with the slide and push, these are known for sticking in the "on" position without even being leaned on. And of course, any 2 coil switch machine like Atlas or Peco that are left "on" for more than a second or two will let out the factory-installed smoke. A CD power supply does a couple of good things:

    - the switch machine is given a good jolt of current (amount determined by size of capacitor) to ensure it snaps over

    - the current is of very short duration because the capacitor discharges very quickly

    - the capacitor recharging current is either limited to a value that will not damage switch machines even if the button is left in the on position, or is blocked by a transistor.

    - most CD supplies can throw more than one switch machine at a time, so that you can use one button to line up all the turnouts in a crossover or similar.

    With a CD power supply, Atlas switch machines normally give many years of fine service. You can use almost any normally off momentary push button or SPDT momentary toggle instead of the Atlas switch controllers. Replacements should ideally be rated at 3 amps or more for long life.

    my thoughts, your choices
  4. green_elite_cab

    green_elite_cab Keep It Moving!

    would this CD power supply be a good idea for quick fix to a porblem? I eventually do plan to removes these switch motors, but it is unclear to me at this time when i'll get around to it. It would cost $100 or more to do this, but i feel like at the same time i've seen those tortoise under table switch machines go for $16. should i just go straight to the good stuff? or am i going to have to make stuff to run them anyway?
  5. 60103

    60103 Pooh Bah

    I would say go for the CDU. It will work with all of the twin coil switch machines, so you can change over if you need to. It will also give you a bit of warning when a button sticks as it doesn't recharge and you can't throw anything else.
    Unfortunately, it won't work with the Tortoise; they need a completely different power supply.
    I think we have a few threads with CDU schematic diagrams if your hobby shop doesn't have one.
    At our show a few years ago, we had a small fire on one layout because of an overheated switch machine.
  6. inkaneer

    inkaneer Member

    An alternative to the electrical machines is to use pnuematic switch motors. Once fairly common in HO they soert of fell out of favor. Del Aire was a company that made them but they are now out of business. EZAire is now producing them.. These have found renewed interest by the outdoor modelers as the air motors are relatively immune from weather. They are very simple in design and operation. They are a cylinder in which a piston is connected to an operating rod. The piston works against a spring. The spring holds the piston at one end of the cylinder. This would be the normal position of the turnout. Allowing air into the cylinder by means of a valve pushes the piston and compresses the spring. Allowing the air to escape permits the spring to push the piston back to the normal position. Very simple as I said. Requires no wiring just a length of vinyl tubing for the air supply. Electrical contacts can be added for signalling etc. The best feature is that these cost about the same as the twin coil machines and are virtually indestructable.
  7. Gary Pfeil

    Gary Pfeil Active Member

    I'm surprised to hear that the Atlas slide switches have problems with sticking. I used them a lot back in the 60's and never had a problem. It was other "off the shelf" type momentary contact push switches I bought from stores like Radio Shack that gave me trouble, tho the machines involved were Kemtron (leter NJ Int.) I have a few Atlas slide switches that I use (only for Atlas machines) for turnouts in hidden staging, I haven't had any problems. I've assumed, with no basis in observed fact, that the Atlas machines don't produce the spike of current when the current is disconnected that the heavier duty machines do. I hope I don't have problems with machines melting!

    BTW, although most of my switch machines are now stall type motors like the Tortoise, I do still use twin solenoid types in some locations, like hidden staging where I utilized what I had. I tried Rix Products push switches, they weld shut easily. I also use diode matrix routing for my staging yard throats, so the current flowing can be considerable. I use a stud and probe to thow these routes. You would think that would eliminate problems, but I had one time when a visitor threw for a route and shortly afterwards we smelt burning. I threw the switch that cut off power to the switch machines. I then found the probe attached to the screw head the visitor had used. It welded itself! I've never duplicated this problem and to this day don't know how it was possible, given the location of the panel (on a slant) and the fact that the probe was a wire that, when not held in hand, would fall to the floor. The probe must have been touched to the screwhead and let go of very gently! Because I use diode matrix routing, and need to be able to throw 5 twin solenoid machines at once, I use a rather powerful transformer. I've found it isn't voltage that limits how many turnouts can be thrown at once, but amps. I have an 8 amp 12 volt transformer powering my turnout machines. A 4 amp, 16 volt unit I had would not throw 5 machines at once. In this case, since the power was free to run, the coils got hot and the heat spread to the metal mounting plate, which started to blacken the wood it was screwed to! It was the wood burning I smelt. I added slow blow fuses to both the input and output of the power supply after that!
  8. zedob

    zedob Member

    If you do a search on ebay for Clippard, or Skinner you'll get all kinds of mini stainless air cylinders and trick toggle type air valves for cheap. If you don't want to buy 10 different styles at one time you can also go to surpluscenter.com. They sell them too, but you can order what you want.

Share This Page