Thanks for running the experiment Ed.
Victor
Here is the result of a little experiment I ran last night.
I found a pair of my older, original Life-Like E-8s with a Digitrax DH123 decoders in them. I was surprized to learn that their top speed was a respectable 83 MPH. For some reason I had expected it to be higher. The pair was hauling a 22 car, free rolling passenger train.
This was recorded after about 20 minutes of "break-in" with my throttle at 99%.
At a designated marker I tripped the breaker on that power district to kill the juice on the rails and measured the stopping distance. It was consistently 39 to 40 inches, about 3 ½ passenger car lengths, on straight and level track. A bit shorter than my original estimate but still a considerable distance.
I still submit that the gap in the rail will have to be quite a distance from your interlocking plant since your equipment will be able to "jumper" that gap and energize the presumed isolated section until the last car passes. With freight, of course, you will only have to allow for the locomotives to pass the gap before the rail becomes dead.
Here is a view of the conductor on No. 29 looking over the test train after it's grueling mission...
Have Fun! Ed
Back when Pike's Peak was still a pimple, I build up a 3 unit set of Alco covered wagons by Hobbytown of Boston. The B unit had a huge Pitman open frame motor in it and the A units had about a pound of lead each and jack shaft drives from the powered B unit. This thing would dim the room lights when you widened out on it, but, once moving it was like the Wermacht going through France. I took it over to a guys house one night where they had an informal club. Their pride and joy was a coal loader and rotary dumper that worked part of the time. This meant cars loaded with loose coal. One guy was running my set of Alco freight engines on the head end of about a 30 car train and when he tried to stop it before he ran out of block, it just coasted into the rear of a coal train sitting on the main and little Athearn hoppers and loose scale coal went all over the layout. What a hoot. I was invited back. The Hobbytowns were not.
Charlie
wabash2800Is it OK to run the DCC track power through the extra contacts on the Tortoise?
From Circuitron:
Hope that helps, Ed
There are a lot of variables here. It turns out to be the total momentum of the train and flywheel. Momentum is mass times velocity. Low velocity does not have much momentum.
I find in my tests that it is a large variable. For this very reason, I have an unpowered section in my test track. I also have a stop. At high power most engines will hit the stop three feet after the power is gone. Some harder than others.
The interesting thing here is the loco's without flywheels stop on a dime, even with a heavy train.
Larry,
www.llxlocomotives.com
So many trains, so little time,
Larry
If what you (the OP) are asking is 'if I set up a section of dead track, like at the end of a stub-end staging yard, do I have to worry about my engines coasting a long way after power is cut?' then the answer is no, probably not. Yes it's true the old Proto E-units would go several feet when running at top (100 scale mph or so) but that's about the longest you can get an HO engine to go unless you have one specifically geared to be able to coast when power is cut...plus, how often are you going to run into staging at 100 mph??
However, if you're asking 'if I don't power my frogs, will my engines be able to 'coast' over the dead spot' the answer is probably again no, or at least, not necessarily. Depending on the engines wheel spacing, some engines might stall while others might not. (Plus of course, a DCC-sound equipped engine may seemingly run through OK, but have the sound stop and re-start due to a momentary loss of contact.) If an engine is having trouble at a frog, you can install something like the TCS "Keep Alive" gizmo so the engine stays under power for several seconds after power is cut off...but then, that may affect the answer to the earlier question about stub-end staging!
Years ago, at a club I used to belong to, one of the members picked up an E unit cheap, and brought it in to test run. It was one of the old AHM ones, but it had been remotored with a coreless motor and it had two brass flywheels on it each bigger than the motor. That thing would coast a good long way.
I always put some momentum on my DCC locos, especially sound ones - that lets me get the effect of the prime mover loading up when starting a long train. Nice thing about DCC momentum, if I turn the throttle up slowly, the loco just starts moving without revving the prime mover, so I can simulate a light engine move, or if I crank it up quickly, the prime mover revs and the loco just barely starts creeping ahead.
I try hard to always switch properly - one thing that bugs me and I see it in so many videos of model railroads - slamming the loco into the cars and shoving them a car length down the track when coupling. If a real switcher engineer did that, pretty sure they'd be fired. And there's be a lot of damaged lading for the railroad claims department to pay off.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
You mean to tell me my engines is suppose to stop on a dime? Whoops!
Very,very few could switch cars with my DCC/Sound engines since they don't stop immediately after the throttle is closed.You need to plan you stops and couplings ahead of time and close the throttle long before the stop or coupling and this is at scale switching speed..
Sounds like the momentum CV is set to high.
Conductor.
Summerset Ry.
"Stay Alert, Don't get hurt Safety First!"
If you're using DCC, the dominant effect will be from deceleration momentum.
But, is the plan to stop the engine from the throttle, or stop it by using a dead section of track? Dead track should stop it pretty quickly. Using DCC momentum slowly reduced voltage to the motor even if the throttle shuts down quickly.
It takes an iron man to play with a toy iron horse.
It's not just big heavy locos that coast on DC. The Bowser Baldwin switchers I have coast a good long way if run up to full speed and have the power cut. Long enough to actually drap something and lay across the rails. This shorts the motor and puts a load on it, causing it to stop. While coasting, the motor is efficient enough to keep the LED headlight lit. These are relatively light and small locos, but they have a high quality Canon can motor in them.
Once a DCC decoder is installed, they don't coast as well, at least with BEMF decoders, unless a little momentum is added to the decoder settings.
wabash2800 I'm told like HO, Proto 2000 six-axle passenger units tend to coast when the power is cut (I assume because of the flywheels and weight).
Yes!
wabash2800at full speed with a full passenger train will coast when the power is cut?
Yes X2!
E-7 and -8s could be ordered with gearing for 85, 92, 98 or 117 MPH and I think Life-Like opted for the 117 MPH 52:25 ratio!
My early Proto 2000 E's (the old Life-Like ones that could do about 90 SMPH, before Walthers re-geared them) would c-o-a-s-t pretty close to five feet when I would make an emergency stop (cutting the power) I've rear-ended a few trains like this.
You have me curious. I'll get a consist of some of my older P2Ks tomorrow, along with my Accutrack speedometer and a stop watch and run some tests tomorrow.
I made a similar setup since I had a drop bridge and a Bascule lift bridge on the same strech of single-track main and I interlocked both to a relay that cut the track power on this entire stretch, about 14 feet total. On the Walthers bascule bridge I designed a little plunger that tripped a small Microswitch under the layout when the bridge went up. On the drop bridge (not for scale but for aisle clearance) I wired a jumper plug that carried track power and other wires for Tortoise and lighting but it had a "loop-back" so when the plug was pulled the same relay would drop killing track power and dropping the signals to absolute stop as well (4 pole double throw relay).
It was pretty handy but NOW I have had at least one close call with keep-alive equipped locomotives... no dead-man pedal. Maybe I need a physical stop on a solenoid that raises a plunger or lowers a "smash-board" like some drawbridges are signalled with, except not a break-away type. Better to smash a coupler than dump a whole train into the river!
Keep in mind, too, that as your locomotives and passenger cars—if equipped for lighting (Walthers) they will bridge the gap once they begin to pass and if the inertia is enough, they will still keep pumping (jumpering) current into the supposedly isolated section. Ask me how I know
Stay tuned, Ed
Victor - I wouldn´t really call that coasting. The distance a loco travels when the power is cut is actually quite short, not more than a couple of inches. If you want real coasting that can be simulated in DCC with a resp, CV setting of the decoder.
In the works are some working split-rail derails on my first model interlocking, though I plan on cutting the power further back then the actual derails, as some locos I'm told like HO, Proto 2000 six-axle passenger units tend to coast when the power is cut (I assume because of the flywheels and weight).
Though I'll be using DCC, what is your experience with the amount of distance an HO loco or two like this at full speed with a full passenger train will coast when the power is cut? (I really don't think I'll carry the realism to the extent that one can derail the train and have it hit the floor!) If you are not sure what I mean, think of how lift gates are usually wired so the trains stop before they get to the chasm.I plan on wiring the track power through the extra contacts on the Tortoise that operates the derail from an Armstrong derail lever in my tower frame. Is it OK to run the DCC track power through the extra contacts on the Tortoise? If not, I have DPDT slides switches hooked to my Armstrong levers available for that.Victor A. BairdFort Wayne, Indiana