# Two blocks?



## muckley (Jan 29, 2014)

I have a small o27 figure 8 layout with a elevated crossing. One half uphill curved section other half is curved downhill. Uphill is too slow, downhill is too fast. It works, but just barely. Is it possible to insulate the two sections with plastic center rail pins and use two phased transformers? One set higher to climb grade, one set lower for downhill section. Are their other things to address? Very new at model trains. I don't want to short out anything. Any advice would be greatly appreciated.


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## broox (Apr 13, 2012)

Could you just insulate the downhill track and put in a resistor? as i picture it in my mind, it would still only use one transformer I think.

Obviously wouldn't work if you wanted to run backwards... Unless you put in some diodes or something, maybe?


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## DonR (Oct 18, 2012)

Do you have enough layout room to lengthen the rise and fall of
the track to lessen the grade? That would take some of the load
off the locomotive and come closer to an even speed.

Don


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## sjm9911 (Dec 20, 2012)

I was going to do this to but opted for a smaller grade over a longer area. Yes it should work, you could use a rheostat. Some may say the different voltages will burn through some wires in some rigs. I don't see that happening, especially if the voltage differential is minimal. You can try and lesson the grade by gradual raising of the flat track. Or, this worked for me, try moving the lock on furthest from the downhill section. Placing it by the upgrade. What trains are you running?


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## gunrunnerjohn (Nov 10, 2010)

Command control with cruise control?


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## muckley (Jan 29, 2014)

May grade is almost 4%. I wish I did have room to lengthen the track to lessen the grade. But my space to limited. I'm running old Marx locos 898,999,666,and a Marlines. I have no idea how to wire a rheostat, but with more information, be willing to consider that option. If blocks do work, without overheating or shorting something, would blocks be a better option? I have an extra transformer. Considering what might work best. Thanks in advance.


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## gunrunnerjohn (Nov 10, 2010)

I think the dual transformer idea might work, you exacerbate the issue with the steepness of the grade, so it'll take some experimentation.


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## muckley (Jan 29, 2014)

Yes, I realize my grade is way to steep. But I'm stuck with it now. What are blocks used for and what are their shortfalls?


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## DonR (Oct 18, 2012)

John

What happens when the loco wheels and 3rd rail wiper
span the gap between the
two AC transformers? What precautions need be done to
ensure correct polarity between them? The 120 V AC plugs
should be marked to ensure they are always plugged in the
same way, shouldn't they? The same with the tract/transformer
connections.

Don


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## gunrunnerjohn (Nov 10, 2010)

Don, you are correct, for this scheme to work the transformers MUST be phased correctly.

muckley, the rheostat is a less than optimal solution as with different loading, or even different engines, the setting would have to be adjusted to work properly. If you use separately powered blocks, you can adjust the voltage on the up and down grades to try to compensate for the different current required. Note that this is not an optimal solution, and it's difficult to impossible for this scheme to work for all cases.

Another way of dealing with the voltage differences required would be pairs of back-to-back 6A diodes to lower the voltage on the downgrade, that eliminates the need for a separate transformer.


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## sjm9911 (Dec 20, 2012)

Eaither way, if you have the transformer why not give it a try. Insulate the track/tracks at both ends and hook up a lock on. After you find the polarity of the plugs a power strip is useful. One plug or switch and your transformers are allready phased.


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