How to conquer garvity question!

[strogey]

On my currrent layout I have included an incline for the first time. I used Woodland Scenics foam inclines. My problem is that the engine tends to gain a great deal of speed when going downhill. I am one that likes to just sit back and watch my trains run and do not want to have to "sit" on the controller. Will the additional feeds that I plan on adding help conquer this proble?

 

Thanks in advance!

Ken

[robscaboose]

Ken  if I remember correctly from my reading the material on the graduated tressle,, you need an engine with (2) motors.  An engine with a single motor needs extra power to go up grade, but then itraces down grade because of the excess power,  Where as a duel motor engine does a better job of mantaining a constant speed & handles the task of going up & down without your handle constantly being on the throttle.

[dsmith]

Hi Ken, my small 027 postwar layout uses conventional control and here's how I control the trains on the inner track that has steep grades.  I have separated the loop into 4 separate blocks by using isolating pins on the center rails - UP, ELEVATED LEVEL, DOWN and LEVEL.  Then, by using bridge rectifiers, you can control the voltage going to each block.  Each bridge rectifier will drop 1.2 volts regardless of the load, so you can accurately customize the voltage going to each block so that you can now operate the train hands free.  Here is a basic diagram of how to wire the blocks.  Add more or less bridge rectifiers to get the speed you want on that block.  I use a 5 position rotary switch so that I can change the number of rectifiers instantly.  Rotary switches are available at Radio Shack and inexpensive(85 cent)bridge rectifiers are from www.allelectronics.com  The whole thing works very well and here are 3 videos of my layout in operation, it's being operated hands free in conventional mode.

http://www.youtube.com/watch?v=yNVtwPxwu3k
http://www.youtube.com/watch?v=rtOEyTIXi2I
http://www.youtube.com/watch?v=I5OnJ8MH8UE

[lionelsoni]

A big advantage of the scheme that David has described, to my mind, is that it doesn't involve unsafe shorting together of transformer outputs as the train crosses the gaps.

You can save on rectifier modules by using a single string and tapping into it at different points for the various voltage drops you need.  For example, the voltage for David's level block could have been tapped from a point between the two modules that he shows for the down block.  For a finer adjustment, you can use the point where the + and - terminals of each rectifier are connected together as a half step.

The voltage drop that this scheme produces is about 90 percent of the forward voltage of each diode, multiplied by the number of diode pairs in series.

[Boyd]

 Is this "garvity" a new type of addiction? I've never heard of it before.

[stuartmit]

David's reply indicates he uses bridge rectifiers which I associate with changing AC to DC current. Am I wrong on that?

[lionelsoni]

That's what they're intended for.  But a bridge-rectifier module is just 4 diodes in one package.  The way they're connected makes it easy to use them instead as a passive voltage-dropping element in an AC circuit, like the one he described.  You could do the same thing with 4 individual rectifier diodes; but it would be more trouble and probably more expensive.