Model Railroading > Keep Alive Queston

How far will a loco with such a device run on dead track?. For example, if I build a safety circuit with the track power cut out when a lift up secton is lifted up, how long of a dead section of track will I have to have to ensure the train doesn't go too far? Keep in mind that some big, heavy diesels like Proto 2000 E and PA units will coast at speed when the power is cut.

Victor A. Baird
http://www.erstwhilepublications.com



Edited 1 time(s). Last edit at 01/13/21 11:40 by wabash2800.

This is a very tough question to answer. It really comes down to the keep alive capacity (capicitor size) and the motor current draw at the speed where the locomotive hits dead rail.

You also need to factor in, if you are running multiple locomotives with KAs, the trailing locomotives will sequentially run off their KAs and will be subject to KA capacity and motor current draw as I indicated above.

My ScaleTrains tunnel motor lasts for a few seconds, which in a derailment might cause some problems. And could be catastrophic for a lift-out. I don’t have one on my current layout, but I would want a foam emergency stop that anchors across the track just in case. The problem would still be me - would I remember to put it in place?

As for dead track, Keep Alives might require a few feet of track just to be safe. To test, fire up the train and cut the power and measure the distance. Crude, but should work.

Nathan

Posted from iPhone

I was working on the layout one day and let a train just run on a continuous loop while I was under the layout
wiring up drops.  In the course of the work I threw a switch on the main, lining it up for a stub siding to check
track voltage on the siding, and then left the switch aligned for siding.  Soon the train came along and I could hear 
it rumble off the end of track onto the bare plywood, then about 3 feet on bare wood and heard a thud on the floor.  

Yup the keep alive did its job all right, and the Bachman consolidation busted its pilot and cab popped off, along with a variety
Of freight cars in various stages of disassembly.

My answer to your question, the TCS keep alive ran for at least 7 seconds.

A split rail derail will take care of this issue.

wabash2800 Wrote:
-------------------------------------------------------
> How far will a loco with such a device run on dead
> track?. For example, if I build a safety circuit
> with the track power cut out when a lift up secton
> is lifted up, how long of a dead section of track
> will I have to have to ensure the train doesn't go
> too far? Keep in mind that some big, heavy diesels
> like Proto 2000 E and PA units will coast at speed
> when the power is cut.
>
> Victor A. Baird
> http://www.erstwhilepublications.com

Very much depends on the capacitance of the KA.  The big ones will definitely run several feet with a good efficient motor.   I did several small HO engines for a layout I used to operate on, and you could put masking tape over the track for a foot or more and they'd happily go right on over it.  We quickly made sure there were track bumpers on any spur leading towards a layout edge and physical stops on our lift bridge gap if it was going to be open for more than a few seconds.

Those of us in N scale who are desperate for anywhere to put a capacitor have less of an issue with it.  I can squeeze in about 980uF in one of my SD60s, which is enough to get it over minor dirt but the power runs out in about 0.25s. 

-------------------------------------------------------
> A split rail derail will take care of this issue.

Not if it is still on its drivers and getting traction on the ties.

If you do it right and your track on a sub roadbed and ditched on the side, the only thing your locomotive is going to be doing is spinning it's wheels on it's side. 


Lighter Wrote:
-------------------------------------------------------
> --------------------------------------------------
> -----
> > A split rail derail will take care of this
> issue.
>
> Not if it is still on its drivers and getting
> traction on the ties.

Now we know the real reason you are "Wrong Way Murphy" 8+)

WrongWayMurphy Wrote:
-------------------------------------------------------
> I was working on the layout one day and let a
> train just run on a continuous loop while I was
> under the layout
> wiring up drops.  In the course of the work I
> threw a switch on the main, lining it up for a
> stub siding to check
> track voltage on the siding, and then left the
> switch aligned for siding.  Soon the train came
> along and I could hear 
> it rumble off the end of track onto the bare
> plywood, then about 3 feet on bare wood and heard
> a thud on the floor.  
>
> Yup the keep alive did its job all right, and the
> Bachman consolidation busted its pilot and cab
> popped off, along with a variety
> Of freight cars in various stages of disassembly.
>
> My answer to your question, the TCS keep alive ran
> for at least 7 seconds.

My ON30 MMI engines will run well beyond 7 seconds but lenght is less than a food because another item is they contiue along at whatever throttle setting you have when power is lost.

My issue is the temporary pause as a train enters an automatic reversing section, it is a short which trips the reversing circuit and while all trains recover and continue there is a slack surge and a sound pause.
Some units lose their healight and other F functions with the reversing circuit short.
My KA units just roll along, making their sound.
I wish there were small sized Keep Alives, just enough to get past the loop entry, over a dead frog or a little dirty spot, say enough for about 0.5 to 1.0 seconds and small enough to fit in any locomotive.
The smallest TCS ones are a step in the right direction.

.... I would want a foam emergency stop
> that anchors across the track just in case. The
> problem would still be me - would I remember to
> put it in place?

Absolutely -- because otherwise you can back a train into the chasm.....[ Not that I've ever done that, of course....]

An electrical interlock that kills power to both sides when the "bridge is up" helps with the memory problem;  recommended, especially if multiple operators.

SZ

Because prevention is better than cure.

If you really want to be sure some kind of physical barrier blocking the tracks when the lift out section is not place will do the job.
And probably will save you some money!

Some newer decoders will allow you set the time that the locomotive will run without a signal from the track. You can use that limit how far they will get on a keep alive circuit

Ted Curphey
Ontario, OR

I shot a  video  a few year ago of how long Keep Alive works. I installed a  TCS KeepAlive in the engine that I frequently
use for track cleaning. See link below
Also as a side note I bought one those tiny two axle Industrial engines that Walthers offered The ML-8. They come with a good keepalive
that actually makes them usable.
https://youtu.be/8TgK-c1yyQI

inyosub Wrote:
-------------------------------------------------------
> I shot a  video  a few year ago of how long Keep
> Alive works. I installed a  TCS KeepAlive in the
> engine that I frequently
> use for track cleaning. See link below
> Also as a side note I bought one those tiny two
> axle Industrial engines that Walthers offered The
> ML-8. They come with a good keepalive
> that actually makes them usable.
> https://youtu.be/8TgK-c1yyQI

Soak that towel with cleaning fluid, and you've got a great way to clean your locomotive's wheels. •ᴗ•

Arved Grass
Fleming Island, FL