Atlas Deluxe Under Table Switch Machine Failures

After what I thought was a very limited amount of usage (probably about 30’ish switches within a few weeks), one of the machines failed. It worked great initially, but then it seemed to drag and not push the points over all the way. I’ve installed several of these, including the regular under table machines, but I’ve had one go and now another one is getting weaker and starting to exhibit the same problem.

I replaced the deluxe machine with a regular machine and everything works fine. The problem is in the deluxe machine. I don’t seem to have any problems w/ other regular machines.

Couple things to point out: I’m using the regular Atlas slide switch (and no, I’m not holding the button down for too long) and the machines that failed were wired to another machine and then to a common switch for a cross over.

Is there an inherent problem w/ the machine? Is there some problem w/ joining it w/ another machine to a common slide switch? Anything else to consider?

Thanks.

Atlas switch machines are all a bit marginal. For reliable operation, use Tortise. (FYI, one Tortise is strong enough to move all four turnouts of a double crossover with a simple linkage)

A CD unit will extend thier life somewhat - but don’t expect miracle.

The Atlas machines are just too small to handle the Joules (energy) needed to operate a turnout over the long term. They heat up, and the insulation breaks down, little by little, each time you lose a turn or more on the coil, and soon there are not enough turns to generate enough force to actuate the switch. A solenoid - like the Atlas machine - produces force proportional to the current in the wire, times the number of turns (ampere-turns).

For more technical information on solenoid design, see a High School Physics book.

I am an Electro-Mechanical Design Engineer.

Hi Nigel,

This intrigues me as I have two of these to deal with at some point. Do you have a drawing of a working model? All of the linkages I’ve come up with are rather complex, particularly moving adjacent sets of points in opposite directions. Would you use some kind of scissor?

Thanks,

Karl

Ive got about 30 of the atlas machines on my layout and have had no problems thus far. The best advice I can give you is to get some proper switches. The atlas “slidey” ones stick sometimes i have found, so even if you arent holding them down too long they may still be sending power to the switch machines. Spring loaded SPDT switches are a necessary investment and they shouldnt be held over at all, a quick tap is all thats needed.

Also check that everything is moving smoothly, lets face it, they are cheap and if you put load on them they will likely fail.

Tortise is definantly the way to go, but if you are like me and just cant convince yourself to spring the money for them you can learn to live with atlas.

EDIT: Forgot to mention that I have the standard ones, so if there is a problem with the deluxe model, I’m not aware of it.

Both the problem and the solution have been posted, but nobody has connected the dots yet.

You’re running this in parallel with another switch machine. When you do that, you need twice as much power, and most likely that’s where you’re falling short. Get a CD circuit, or build one. That’s a Capacitive Discharge system, and the parts will cost you less than $10 at Radio $hack. You can also buy one pre-made, but they’re more expensive. A CD circuit will make all of your twin-coil machines perform better. If you’re thinking of Peco turnouts and their switch machines, you’ll certainly want a CD circuit.

I’ve got some old Atlas switch machines on my layout. They haven’t been in continuous service, but one or two of them are over 50 years old, and still running.

i agree on all point above, the atlas pushbuttons that come with the machines arnt that good and stick, thus pre maturerly burn up the coils. and that a CD unit really helps.

Can anyone please advise where to get a schematic and parts list for the CD circuit mentioned above?

moldel RR has three electronis books out with the circuits or try google it, i think the electronics books are outa print

Better yet, try searching CD switch machines here. There are probably five or more pages and one should be able to find the link to the online circuit diagrams that include the CD amplifier and other useful items. I still have the diagram but didn’t copy the web address. Good luck J.R.

This is one of over 300 thousand Google references to Capacitive Discharge circuits for model railroads:

http://home.cogeco.ca/~rpaisley4/CDPSU.html

Other things to consider - if the turnout machine has gotten sluggish, you may have gotten something in the throwbar linkage. When I mount an Atlas turnout, I try to hollow out a slot in the roadbed below the throwbar to prevent this. If you’re using WS foam, it might shift a bit with ballasting or track adjustment and put enough pressure on the throwbar to inhibit motion. I’ve had this happen with Atlas above-table machines, but the principle is the same for below-table.

Get rid of the Atlas pushbuttons. The previous poster was right. They will stick, and that will burn out your switch machine. (Another benefit of CD circuits - the protect against this problem.) Unfortunately, the way you know this happens is probably that you’ll recognize the smell of a switch machine melting. You’ll recognize it the second time, anyway, and you might get enough time to pull the plug before it’s toast. The first time, it will be, “What’s that smell?”