2 solutions...

Dear Nathan,

Option 1:

Assuming you're looking for a "standalone" solution,
and not a "DCC controlled" turnout-throwing solution,
and that you're a "code in solder" rather than "code in code" modeller,
I would reccomend checking out the "Stall-Motor driver circuit" from Rob Paisley's "Model Railroad and Misc Electronics" website...

http://circuitous.ca/556Stall08.html

Specifically

The normal "turnout throw" buttons connect between the "R" and "N" terminal and the " - " (Circuit GND) line.

The Tortoise motor connects at "A", to the "LH" and "HL" terminals.

The dropleaf "force-direction" pressure-switch should connect between the pin labelled "10"
(the "Reset" line of the circuit) and the " - " (Circuit GND) line.

You'll need one such circuit for each Tortoise motor, but the "Reset" lines of both circuits can be fed from a single "dropleaf pressure switch".

The "polarity" of the Tortoise motor, IE the way it's connected to the "LH" and "HL" terminals
should be "strategically arranged" such that the "Reset" line sets the trurnout to the "fail-safe" routing in your particular circumstance. 

The "normal" turnout-throw push buttons can then be connected and mounted-in-the-layout-fascia whichever way matches the required "normal method of operation" turnout throw direction and config.

Option 2:

If you're more of a "Code in Code" kind of modeller,
a quick spin with the Search box at top right of this page, with the terms "Arduino Turnout" should give you plenty of fodder to build-up and code a Arduino based solution.

A single Arduino Pro Mini should have enough I/O pins to:
- Handle "Normal" and "Thrown" buttons for both turnouts
- Handle at least 1, likely more, "drop-leaf pressure switch" inputs
- drive 2x Tortoise turnout motors (likely with the assistance of a "Servo" or "Motor" shield add-on board)

The code should be able to take care of the "normal" turnout-control button input commands and resulting Tortoise moves, and the "Dropleaf over-ride"/"fail-safe" inputs and behaviors...

...and would potentially allow both "local button" and "DCC accessory command" control options...

...and should be quite cost-effective in the bargain...

I hope this helps...

Happy Modelling,
Aim to Improve,
Prof Klyzlr

Why not mechanical?

Since the drop leaf involves a roughly 90 degree motion, why not use that to activate rods that pop-up on the wye tracks?  Not only fail-safe, but could allow spotting a car or 2 on the wye if there is enough track length.

Another idea

I have a drop leaf that crosses the doorway into the room.  I powered the leaf that in turn powers three feet on each side.  When the leaf is out, there is no power to the tracks on either side and nothing lands on the floor.  I've experienced that sickening feeling.

Ken

To what extent does this assume no DCC keep-alive caps?

If you need it, Geoff Bunza's DCC station can broadcast an E-stop. http://model-railroad-hobbyist.com/node/25045?page=3

Turnout routing = no issue with ka/ck

thinking a bit

thinking a bit differently....hard to explain in words but i can visualize the concept. Bear with me on the explanation.

how about a mechanical locking mechanism that maintains/secures the wye in the "useable" position.

if one (or both) of the torts aligning the switchs towards the wye would then activate a locking mechanism forcing the wye to be locked in it useable condition.

this locking mechanism can only be "unlocked" if both switches are aligned for "not the wye".

when the wye is removed / not in service, it would disconnect the electrical path heading towards the wye torts; no power, no switching to the wrong path.

I built something...

...to do the same for a friend of mine. A microswitch with a roller actuator was operated by an "L" on the drop leaf. this actuated a relay which overrode the normal toggle switch operation og the Totoise motors leading to the WYE and set them to the straight position. We were using a split potential power supply to run the Tortoise but if you were using a DPDT switch to actuate it you could modify the circuit to do the same thing with 2 change over contacts to switch power. As you will have 2 tortoise motors you will need to duplicate the circuit for the second motor.

This is pretty fail safe, the only issue would be if the drop leaf did not drop completely and fail to actuate the microswitch.

Alan L's "Interlocking"

Dear Alan, Nathan,

Sounds like a simple solenoid is called for

http://au.element14.com/w/c/switches-relays/solenoids/linear-solenoids/prl/results?st=solenoid

Given that the Tortoises have attached micro switches, simply wire one SPDT switch from each in "OR" config,
so that power is applied to the solenoid when either/both of the turnouts are thrown for the wye.

This would require a seperate DPDT pressure-switch,
(or a pair of SPDT pressure-switches),

mechanically-activated by the dropleaf,
which cuts a line to each of the two critical tortoises.

It's "coding in solder" (which is vaguely "out of fashion" in many areas now-a-days),
but sure, it certainly is a workable solution...

Happy Modelling,
Aim to Improve,
Prof Klyzlr

KISS Principle

He told us how to do it in his want list. Wire a SPST Normally Open push button in series to the power supply for the two tortises. You have to hold the button down while you activate the switch machines. As an interlock wire the power to one rail of each leg through the contacts of the tortise.

With this sheme it makes no difference how you control your tortise. They only work with power no matter how you do it.

Espee over Donner

This would be a good introductory project for

an Arduino.  

Nick

KISS Principle

   I like simple :> ) For my lift outs I prefer a hole drilled in the center of the tracks with a phillips screw driver stuck in it when the bridge is not in place.....DaveB 

Kiss Principle...

" Wire a SPST Normally Open push button in series to the power supply for the two tortises. You have to hold the button down while you activate the switch machines. As an interlock wire the power to one rail of each leg through the contacts of the tortise".

...this is fine to stop the turnouts being set for the wye and oblivion but what if the turnouts are set to the wye already nothing will stop that drop in this case. Something needs to set the turnouts away from the drop and not allow them to be changed until the drop leaf is lifted!

Hence the circuit in my post above.

Thank you for all the

It may be a little late...

but how about making the tail of the wye lift up rather than drop down?  In the verticle position it would act as an absolute barrier to any errant equipment.

yes, the 2am answer is always

yes, the 2am answer is always the best. A momentay push button to operate the turnout has a flaw. if the button is not kept pushed in while the train is passing over (human error), it will likely cause a derailment.

Here's another idea..

put a DPDT push button in a location that will be depressed when the lift out is in place for use; 1 for each tort.

power coming from the power supply will go through the lift out DPDT switch, then to the turnout DPDT switch. When the lift out is in place, the power is directed towards the DPDT that operates the Tort's #1 & 8. When the lift out is removed, the power is directed towards the Tort's #1 & 8; specifically to line the Tort away from the "drop zone".

When the lift out is in place, the turnouts DPDT switch will operate the turnout direction. When the lift out is removed, the Tort is automatically lined away from the drop zone. Yes, there will be 2 sets of power feeders on the Tort's #1 & 8, but only 1 set will be carrying the power. Electricity will flow "backwards", but will not cause harm because it hits a dead end once it gets to the lift out DPDT switch.

This should easily solve your issue with minimal wiring.









































 

@ Alan...

...That is what my circuit i posted earlier does. one switch and a relay instead of 2 switches.

Wazzzy, yes that is what I

Wazzzy, yes that is what I built. The 'safe' position keeps the momentary depressed, and allows for normal operation. The 'unsafe' position releases the momentary and the polarity is such that the turnout is lined normal.

Crappy MS Paint drawing attached. 

I'm happy you could

My 2am reading skills are terrible. I thought you were using a single momentary DPDT to operate each turnout. Thus my operator error comments were not valid for this application.

My 2am writing skills aren't any better. I tried to insert a "crappy" drawing and couldn't get it to upload.

Your drawing matches what I was thinking.

Its not that one idea is better than another, but collectively, we the MRH forums, helped develope a plan that suits your needs and skills.

Keep us updated on the installation...

Not fail safe

Electrical solutions are not fail safe unless the electrically dead section is long enough to stop a backing train.   Not a pleasant sight when such a section is too short.

Stopping a backing train

I am visualizing a mechanism where the drop leaf holds a spring-loaded pin in, and when dropped the pin extends, lifting by means of a bell crank a pin in the middle of the tracks. 

Which would block the tracks. 

Might need to manually retract the pin to lift the leaf back in place, but perhaps the leaf could do the work. 

Stopping a backing train...

...is not neccasary if the lockaout mechanism returns the turnouts to the "safe". position. that was the point of my circuit I posted earlier. if the leaf is lowered the turnouts move to the safe position therefore a back ing train will stay on the "main".