As always, I appreciate all the helpful suggestions I receive from my queries.
This might be much to do about nothing. I only have one locomotive with a capacitor, a shay. I just tested it going full speed (which is very slow on a shay) and when I cut the power to the track it stops within an inch! I suspect a faster locomotive would take a little longer to stop, but probably only a few inches, not a few feet.
That said, it is perhaps still prudent to have some sort of removable bumper (and yes with padding) to stop me from foolishly backup up an entire train into oblivion.
JPD This might be much to do about nothing. I only have one locomotive with a capacitor, a shay. I just tested it going full speed (which is very slow on a shay) and when I cut the power to the track it stops within an inch! I suspect a faster locomotive would take a little longer to stop, but probably only a few inches, not a few feet. That said, it is perhaps still prudent to have some sort of removable bumper (and yes with padding) to stop me from foolishly backup up an entire train into oblivion.
You might think. I have only one loco with a full size keep alive, that's a Walthers Plymouth switcher. If I take that loco off the rails, I can put it on my workbench and it rolls halfway across to the edge, where I pick it up to keep it from falling and put it back in the middle - where it again reaches the edge. The third time it doesn;t quite make it - it runs probabl for a good 30 seconds once charged up, it's like a windup toy.
This is compeltle unecessary and unacceptable - and one reason why I have not bothered with any of my other locos. I've never had a problem with sound cutting out, or even headlight flickers.
If I DO install any, it will be one of two types. Either a standard capacitor (not supercapacitor) so it's good for less than a second, just to keep things from stuttering over one piece of dirt on the rail, or else they will be the proper 3 wire type to go with my (exclusively used) Loksoudn decoders - because with that third wire, it allows the cap to be disconnected for programming, and it also allows you to set a run time, regardless of how much energy is stored. ANd I would set them to a second or two tops, because you should never need more than that. If you need 10-15 seconds of keep alive power - clean your track.
Yes, I have strong opinions on some things - and get off my lawn while you're at it!
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
Randy is one of the senior knowledgeable people here about electronic matters.
I would rephrase the discussion, though, to include a legitimate use of 'autonomous battery power' on layouts: what happens if you have liftouts and are running 'dead rail'. (Corollary for garden railroads and so forth with radio remote control that might not always be disabled in time...)
It occurred to me when I first started looking at this that it might be possible to have a thin wire in a Bowden cable sheath, arranged so that comes up from the track, like the little 'finger' on an IBM Executive typewriter, when the liftout is unlocked or removed. This would engage a small microswitch or other trip installed on the pilot beams of battery-powered locomotives, to cut power quickly and unambiguously in emergency. This might be stout enough to hold an errant rolling car or consist, too.
We have discussed a number of lift-up and other 'interlocked' devices to block track within the past few weeks, if I remember correctly, and perhaps someone can find and reference that discussion (as I recall, it involves hinge-down panels).
I think a padded physical stop is good enough. If you aren't paying attention to where your loco is going and approach the raised or removed giant gap at warp speed, well.....
Though for true dead rail battery powered, it wouldn't be a bad idea for there to be some way to kill power so a loco doesn't just sit there and spin its wheels, or worse, get stalled and fry the motor.
rrinkerThough for true dead rail battery powered, it wouldn't be a bad idea for there to be some way to kill power so a loco doesn't just sit there and spin its wheels, or worse, get stalled and fry the motor.
The approach I had lo! these many years ago was to use multiple reed switches in parallel, arranged under the chassis somewhere, not necessarily on the centerline of the locomotive or even within the gauge, with a coded pattern of magnets that would open them all (thereby interrupting motor power) if you went beyond where you were supposed to go. The magnets could be stuck on tape to make a portable 'array' stop of comparatively low obvious visibility. Most other kinds of magnet (uncoupling magnets for example) would only open one or two of the reed switches at most, so wouldn't cause 'interference'.
There are probably better ways to do this now.
How wide is the lift-off section, and the surrounding territory? Could you put a protective pad or a safety net at the end of the fixed layout?
It takes an iron man to play with a toy iron horse.
MisterBeasley How wide is the lift-off section, and the surrounding territory? Could you put a protective pad or a safety net at the end of the fixed layout?
The gap for the lift out is three feet and there is at least five feet of streight track on either side of the gap. I was thinking of isolating about 18 inches on either side of the gap.
Can you make the lift out 5 feet long, with the center 3 feet being the main lift off and thin extensions going a foot on either side? When the lift off is removed, you would have a 1 foot shelf that you could pad as a runaway cushion. The extensions would cover the cushion when the lift off is in place.
OvermodIt occurred to me when I first started looking at this that it might be possible to have a thin wire in a Bowden cable sheath, arranged so that comes up from the track, — This might be stout enough to hold an errant rolling car or consist, too.
My "hill-holder"
car_stop2 by Edmund, on Flickr
When it is engaged a flickering fusee "protects" the standing cut of cars.
car_stop3 by Edmund, on Flickr
Here is the works of the operation:
car_stop1 by Edmund, on Flickr
I operate this setup with a HumpYard Purveyor quadrant lever but you could just as easily use a Tortoise or spring-loaded plunger rigged to a lift-out.
car_stop5 by Edmund, on Flickr
For informational purposes only,
Good Luck, Ed
JPD The gap for the lift out is three feet and there is at least five feet of streight track on either side of the gap. I was thinking of isolating about 18 inches on either side of the gap.
The gap will work for non keep-alive equipped locos but might present a new wrinkle when a keep-alive loco enters the non-powered section: It will keep going at its original speed and direction and ....... you won't have any way to stop it because it isn't receiving commands from the system on the dead track, guaranteeing a runaway. Even if you do notice it in time you won't be able to stop it. I would go with a version of Ed's idea.
I have a swing gate and two lift outs on my layout. I haven't had any problems with runaways or locos hitting the floor (knock wood) in more than a decade of running on the layout. I don't have any kill switches or dead zone safety measures in place.
It is worth noting that during ops sessions and regular layout tours, the upper lift out is left in place, the lower liftout is only installed during Ops and the swing gate is never left open - I find it easy to keep track of the issue.
The biggest issues I have with keep-alive equipped locos (nearly the entire fleet) is that they will run through incorrectly set points. The short won't stop them. Overall, a small price to pay for the much improved performance the keep-alives provide. Randy - I'll stay away from your lawn .
Guy
see stuff at: the Willoughby Line Site
Our club has a very simple solution to prevent swan dives to the floor when the liftout is 'out'. The liftout, which bridges the gap between our staging yard and the main layout, uses large entry door style hinges to control the alignment. There are holes drilled into the middle of the approach tracks just before the liftout. When the liftout is removed, the hinge pins are inserted into the holes in the approach tracks. Crude but effective! They are hard to miss. We don't give a rodent's rear end about the fact that the pins are not padded. If you are stupid enough to run your train fast enough in the staging yard that it might hit the hinge pins, or not notice that the bridge is not in place, that is your problem!!
Dave
I'm just a dude with a bad back having a lot of fun with model trains, and finally building a layout!
Does no one make a simple DCC booster that can transmit the E-Stop command?
It could be connected to a segment of track (a power district) before the liftout, and when triggered by removing the liftout starts transmitting a stop command in that segment. A DCC locomotive enters that district and immediately stops. No matter what. No need to worry about a keep alive either, because the decoder is told to stop.
Automatic Brake Control is one solution, but it requires specific decoders with that feature built in. Using the E-stop works with all decoders.
Something like this could be implemented with the RPi or Arduino.
WOW, Randy, don't want to high jack a thread, but what kind of keep alive do you use? I have installed my shre of keep alive and I feel lucky to get a loco to run over 4 inches of Kepton tape on both rails. I can lift a loco off the rails with just the sound on and the sound will remain on for 15 to 30 seconds--- if the motor is running when I remove the loco it is lucky to remain running for 10 seconds- most time less.