turntable/roundhouse

[SteamGene]

Is it possible to assemble the roundhouse, service, and garden tracks and then place the turntable, or must the turntable be in place first? 
I just discovered that I can work on the engine facility through the hole the turntable fits in, making it suddenly easy to do the area by myself - if I can install the turntable last. 
The turntable is the Walther's 130 foot and the round houses are Walthers. 
Gene

[pdlethbridge]

My layout plan was to install the turntable first so I could position each track for the roundhouse. The turntable is removable as I changed the way the bridge tracks were cut. The bridge tracks are the same length as the pit lip and the other tracks end at that spot. If I had done it the proper way, the bridge tracks would have ended at the pit wall, and all other tracks would overlap the pit lip. If they had, the turntable would NOT have been removable. This image shows it clearly. If you look closely at the near end of the turntable you can see the bridge rails extend to the track over the pit lip but the 2 next tracks don't cover the lip. I don't know if the 130 foot walthers turntable has the track installed or not, my 90 foot didn't, which made it easier to extend the bridge track.

[SteamGene]

Track is installed on the bridge.  I think I can put the turntable in temporarily and verify the position of the track. 
Thanks for the response. 
Gene

[SteamGene]

The answer to my question is, ultimately, no.  The track has to fit over the lip of the pit, so the pit has to go in before the track is fastened down.  But I can do a lot of other things.   If I can get my wife to get her things out of storage in the barn, I can get the above creeper to the engine facility and see if I can work on the service track on it.  If so - I'm good to go. 
OTOH, has anybody laid cardboard or something else over track to work on a level above the track? 
Gene

[pdlethbridge]

Now here is the $64 question. Is their any way you can safely remove the track so you could do what I did? Sure is easier to have things workable from above.

[rogertra]

Gene.

Although mine is a 90ft 'table, you can see from this installation phase top view of the pre-weathered table that rails for the roundhouse and field tracks need to go over the "concrete" lip to reach the 'table.

Unfortunately for you, this means that the pit has to go in first.

However, if you are prepared to end your leads say two inches from the pit, finish the work you need to do, then infill the two inch gap between the 'table and the leads, it may work.

[SteamGene]

I'll work it out. 
Roger - your service/garden tracks - they go just to the edge of the pit, correct?  Did you file the inside of the rails that "contact" the bridge rails? 
Wiring the roundhouse/garden tracks.  If the service tracks have say, positive on the right and negative on the left, do I need to wire the other end of the bridge positive on the left and negative on the right?  The instruction sheet says the bridge reverses polarity - but what about wiring on the other side?
Gene

[ebtnut]

Here's the "old school" way to power a turntable.  The pit rail needs to have two gaps in it, 180 degrees apart.  These gaps are normally placed at about 90 degrees from the lead-in track(s).  The trucks under each end of the table are wired to the table rails--one truck to each rail--and pick up power from the pit rail.  Each half of the pit rail is wired to one of the rails coming in from the yard, such that the polarity matches from running rails to table rails.  Thus, when you turn the table around, the polarity automatically changes to match the entry rails.  The roundhouse leads are normally wired through on-off switches so that you don't accidentally run a loco you didn't want to move.  But again, their polarity should match the polarity of the lead-in track(s).  Hope that's clear.

[pdlethbridge]

If you look at my picture, all the left rails are wired the same and the right rails are wired the same, with on/off switches. The only thing that is wired separately is the bridge track, and thats on a auto reverse switch, DCC. This Walther's 90' works great but what made it easier to use was extending the bridge rails. The only other suggestion would be to notch out where the tracks will go or remove the lip entirely and support the turntable from underneath. A very expensive prospect if you do it wrong but the rewards are in ease of use.

[pdlethbridge]

EBT, on the Walther's turntable, the pit rails are plastic and the bridge track receives power from 2 rings located on the center shaft that are separated by a plastic ring.  2 wipers contact each brass ring and give power to the tracks this way.

[rogertra]

Gene.

All the right hand tracks in the photo are the common and are simply linked together with a wiring harness under the roundhouse which itself connects to the railway's common return wiring.

The power (hot)  for the garden tracks and roundhouse tracks is taken from the block that powers the inbound and outbound leads (Out of the photo in the bottom left corner of photo) via single pole, normally open, push buttons.  One for each roundhouse and garden track and two each for each inbound and outbound track.  Those on the inbound and outbound tracks are for isolating locomotives, maximum three on each track.  One loco in each push buttom block and one on end of each track near the switch.  Just the way my track plan wor

I still use DC so the power for the whole roundhouse complex, other than the turntable motor, is controlled by a DPDT electrical switch which permits either the East or West throttle to control the roundhouse yard.

The 'hot' line to the turntable bridge is also fed via a normally open, single pole, push button.  You could replace the push buttons with on/off switches if you wanted to but you could forget and leave one of the 'open'.

There is no need for any reversing electrical switches and that's all done automatically by the turntable as it rotates and, of course, only effects the 'table bridge.

Even if you use DCC, I'd still recommend either push buttons or on/off electrical switches for all the roundhouse tracks, including the inbound and outbound leads to the 'table as a safely precaution.

Having push buttons is not a big deal as I have momentum throttles and locos are moving slowly in roundhouse yard.

[ebtnut]

Paul:  I haven't yet seen the Walthers TT "in the plastic" as it were, but their power method is the same trip via a different (and probably more reliable) route.  Thanks for the update.

[SteamGene]

Roger, et al, I've already decided, despite the fact that I'm using DCC, that all the South River Yard trackage, including the roundhouse will be wire with an on-off switch.  I don't want to turn the power on and hear fifteen or so steam locomotives turn on.  Probably too much of a power drain to begin with. 

So, if I understand it correctly, the service tracks to the turntable and the roundhouse/garden tracks should both be wired the same way.  So if the service tracks are wired with positive towards the wall, then the roundhouse tracks should be wired towards the wall. 
Correct?

Gene

[Jim Banner]

So, if I understand it correctly, the service tracks to the turntable and the roundhouse/garden tracks should both be wired the same way.  So if the service tracks are wired with positive towards the wall, then the roundhouse tracks should be wired with positive towards the wall. 
Correct?

Gene

Correct if you accept my addition to your quote.
From pdlethbridge's description, the turntable does not automatically reverse polarity (phase) as it turns and an auto reverser is required.  In this case. it really doesn't matter which way you wire any of the tracks at the turntable as the auto reverser will take care of it.  (Of course, any tracks connecting to the rest of the layout will have to match phase with the tracks they connect to.)

Advantage of this system is its universality.  There are situations where the split pit rail scheme does not work.  In the usual setup where a continuous pit rail forms one path to the bridge track and the centre pivot forms the other, this system is more reliable than a split pit rail.  As implemented by Walthers, it may well be more reliable also.

Disadvantage is the extra cost for the auto reverser. 

[rogertra]

The Walthers Built Up turntable DOES automatically reverse polarity as it rotates.

An auto-reverser is NOT required.  At least not for DC.  I don't know about DCC but it is covered in the instructions.

With regular DC, if your loco enters the table with the direction switch on your thottle set for the loco to move left to right, after it turns around you do NOT need to change the reverse switch as the loco will still move left to right.

Gene. 

You should always wire a model railway with the common and hot wires consistant.  DC or DCC it doesn't matter.  Pick one and stick with it.  "Hot to the north" for example.