N Scale Hi Rail - Retro Hollow Core Door Layout

[wm3798]

If the center pivot/bearing for the bridge is accessible from the bottom of the turntable, you could install a cam on it.
The cam would then operate a DPDT snap switch (with a roller lever actuator) that reverses the polarity to the bridge track over a specific segment of the arc of its rotation.

It is accessible, and I actually have a spare parts turntable I can make use of if necessary.
Do you have a diagram of the cam set up?
Lee

[Point353]

It is accessible, and I actually have a spare parts turntable I can make use of if necessary.
Do you have a diagram of the cam set up?
Lee

No diagram, but simply a disc with sections of two different diameters, or depths, depending upon how you want to install the switch.
The switch would be of this type:

[nkalanaga]

For speed control on a Retro layout, using DC, I have a very simple method on my narrow gauge.  Since the loco shouldn't move while the turntable is turning, use the throttle to power the turntable. 

I have a rotary switch to power the roundhouse tracks and turntable lead, and a DPDT toggle for the turntable.  The turntable lead, turntable, and roundhouse tracks are a single block as there's only room for one loco at a time to run anyway.  The turntable is always "hot".

To put a loco in the roundhouse, set the toggle to "engine",  set the rotary switch for the lead, run the engine onto the turntable, and throw the toggle to "turntable".  Use the throttle to turn the table to the desired track, with the engine facing the desired direction.  Set the rotary switch to the desired track while the table is turning.  Return the toggle to "engine", and run the engine off the table.

In my case, I only have one throttle, and can only run one train at a time anyway, so no cab controls are needed.  If you want to run more than one train, add a cab selector switch for the roundhouse area, just like any other block.

My turntable is one of the aftermarket0powered Peco models, rebuilt for Nn3, so it has automatic reversing.  For one that doesn't, I like the cam-and-switch design from Point353.  Old-school electro-mechanical - perfect for a Retro Railroad.  The cam doesn't have to be perfectly round, as long as the switch arm can follow it.  Any disk will do, with a chunk cut out deep enough that the switch arm can fully extend, and the edges tapered so the arm doesn't snag.  Be sure to put the "edges" so they don't line up with any tracks!

[wm3798]

I like that idea, @nkalanaga .  Even if I was to convert the roundhouse to DCC, I'd want to isolate power from the storage tracks.  Especially if a sound loco ever made it into my life (never say never!) I couldn't bear the thought of all those headlights and noisemakers sitting their running all the time.
The trick for me will be to have the ability to route power to as many as 25 or 30 fan tracks.  Less of a problem with DCC, I could just have a 5 position switch that turns on 5 or 6 tracks at a time, then control the individual engines.
But for DC, I'd need to be able to isolate each track individually...  Maybe a 10 position switch and a suitable number of momentary contact switches?

@Point353 I'm not sure what gets connected to what.  Obviously the two terminal on the left go to the main track power, and the ones on the right providing +/- -/+ switch?  Not sure what the springy gizmo connects to.. I assume that's some sort of actuator.  How would it physically connect to the turntable?

On turntables past, I simply had a DPDT wired to the bridge track, and by throwing it either to or away from the direction of the doghouse, I pretty much always got where I needed to be.

@DKS , that system is pretty much how the newer Walthers turntable works.  It had four buttons on the controller as I recall.  Fast right, slow right, and fast left and slow left.  The indexing system was reasonably good, but over time would drift, so it was handy to have the slow button to nudge the bridge into alignment.

Lee

[DKS]

[DKS]

But for DC, I'd need to be able to isolate each track individually...  Maybe a 10 position switch and a suitable number of momentary contact switches?

Install a magnet in each end of the turntable bridge. Then install a reed switch behind the wall of the TT pit connected to each track. That way, only the track with which the TT is aligned will receive power.

[DKS]

No diagram, but simply a disc with sections of two different diameters, or depths, depending upon how you want to install the switch.

Don't even need a disc with two diameters; just one with transitions.

[sd45elect2000]

Don't even need a disc with two diameters; just one with transitions.

Believe it or not, this looks and behaves exactly like the throttle in an actual locomotive. Just add 7 more switches and 3 more for dynamic brake, 2 for forward and reverse...

good plan !

[DKS]

Believe it or not, this looks and behaves exactly like the throttle in an actual locomotive. Just add 7 more switches and 3 more for dynamic brake, 2 for forward and reverse...

Yes, I believe it, because I've worked on the throttle of a 1940s diesel switcher...

[sd45elect2000]

Yes, I believe it, because I've worked on the throttle of a 1940s diesel switcher...

That's great exposure to tech of the day, they were clever.

[nkalanaga]

Lee:  It would be more expensive than a rotary switch, but a diagram with toggle switches for each track would work fine for DCC.  Turn any track you wish on or off at any time.

For DC, the pushbuttons could be used the same way, if you're willing to hold the button while the loco is moving.  That shouldn't be a problem, as long as you're standing there anyway, and the throttle can be worked with one hand.

[wm3798]

The challenge there would be building a control panel big enough to include 20+ toggle switches...

[peteski]

The challenge there would be building a control panel big enough to include 20+ toggle switches...

I think DKS' idea of using reed switches and a bridge-mounted magnet to power the tracks aligned with the bridge is very clever, but probably too "hi-tech" for this layout.

A rotary switch would probably be the most period solution.

[wm3798]

Hand that man a pierogi!  Peteski has nailed it!  Being blessed with two left hands when it comes to all things electronic, I think I'll stick to the primitively simple push buttons/rotary switch concept. 

I've got plenty of time to sort out the control... I'm crating it up this weekend to keep it in safe storage until such time as we buy a basement somewhere with a couple of rooms above.  Turns out I have another nearly complete turntable and motor, so I can do some laboratory experiments if I care to...

Here's a tidied up look at it with the building repairs done and the paint touched up... and a few residents who are looking forward to a more permanent home...



Lee

[nkalanaga]

A solution if you want all rotary switches:  Divide the tracks into groups, with the groups on one switch.  The, route each group through it's own switch, to choose the track. 

It looks like you have about 20 tracks (I didn't count too carefully), so a 3-position and 3 8-position switches will do the job.  That would give 24 tracks, more than enough.  Use a larger main switch if you might add more tracks/groups in the future.

No need for an accurate diagram, just a main switch, lines from it to the group switches, and number the tracks on the group switches.