Steam & Excursion > ORHC - turntable update 1/24

the anticiapted placement of the pivot will be in some days as first the rim rail needs finalizing (not sure what all that means).  meanwhile, more rock on the pit bottom and compacting, then compact testing .  the pivot has been moved outside, now with interpretive signage, to have it ready when Omega Morgan wants it.  weather here in Portland is absolutely perfect for January, 50, no rain.         Arlen 

Thanks for the update! even if there isn't anything new to photograph

Victor Baird



Edited 1 time(s). Last edit at 01/25/23 09:56 by wabash2800.

And about that weather, no rain coming in the weekend? Um will see.
 

Here is a photo as of late afternoon 1/25/2023. Re-bar and forms are being brought in to start forming the "spokes" that will extend from the center pivot out to the outer wall of the turntable pit.

---

Well that's interesting...wonder what their purpose is?

Cheers, Dave

I've never seen 'spokes' in a TT pit, before.
Mostly, I've seen complete 'discs' of concrete forming the
circular floor --- with an off-center rain grate.

But, that's 'old school' , there's no structural requirement about using 
an entire concrete  pit floor.

My guess is that with sawdust/dirt  that deep, and the long steel pilings,
there's a chance of so much weight ( on the table)which might cause the supporting
steel support  shafts to bow, or lean off-center.

The spokes must be designed so that they counter such potential leaning and possible 
instability. ---- Its as if the soil was so much gooey mud...there's no lateral support,
or restraint in mud.

My inexperienced brain would not have anticipated such wobbling --- but hey, 
a combined-weight of loco, tender, & TT bridge could collectively weigh
well over a million pounds .... that's a lot of weight to balance on the top of those
long, steel pilings; and, ( in the deep 'mud') things could get wobbly, very easily.

You don't want the bridge-ends, with a million pounds load,  to be forced  into that
circular concrete pit-wall ----you'd never be able to budge it, with a loco on board---
- if such 'leaning' were to happen!   There's only a couple of inches clearance between
the ends of the bridge, and the circular pit-wall.

The testing & procedure they use to check that close-clearance spacing --- all the way around,
under load, will be an interesting thing to watch.  
They're NOT gonna just stick the 4449 on it, and "see what happens"!

If it DID get stuck....it would be wedged there permanently! 

Good thinking!

​W.



Edited 2 time(s). Last edit at 01/26/23 13:32 by wcamp1472.

<G> <G> <G>

Date: 01/04/23 21:20
Re: ORHC - turntable update 1/3/2023
Author: wabash2800 One would think that sawdust would decompose and not make good fill...

Victor Baird [ Reply To This Message ] [ Quote ] [ Private Reply ] [ Edit ] [ Delete Post ]



Hillcrest Wrote:
-------------------------------------------------------
> Well that's interesting...wonder what their
> purpose is?
>
> Cheers, Dave

As I understand the spokes will be there mostly for aesthetics. The foundation for the center pivot and the outer ring will support the turntable and locomotives you put on it just fine. Once the spokes are poured, it would be my understanding that the voids in between each spoke will be filled with gravel to be flush with the top of the spokes and the lower wall.

Wes, I like your theory.  Long columns, anchored at the bottom but surrounded by mud higher up don't seem like a safe bet for long term stability.

But if the spokes are intended to be structural, it's puzzling they didn't cast the wall and the center block with rebar sticking out and perpendicular surfaces on the block at the locations of spoke attachment.

Elesco Wrote:
-------------------------------------------------------
> Wes, I like your theory.  Long columns, anchored
> at the bottom but surrounded by mud higher up
> don't seem like a safe bet for long term
> stability.
>
> But if the spokes are intended to be structural,
> it's puzzling they didn't cast the wall and the
> center block with rebar sticking out and
> perpendicular surfaces on the block at the
> locations of spoke attachment.

Not sure you could do that with the steel forms they where using.

They could pin the spokes into the outer wall. That's what they do with parallel concrete panels on a freeway.