Author Topic: Sheepscot Turntable - Official Work Thread  (Read 70907 times)

John Kokas

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Re: Sheepscot Turntable - Official Work Thread
« Reply #15 on: January 11, 2016, 01:21:31 AM »
Many old narrow gauge and shortlines used scrap boiler tubes for their turntable poles.

Joe Fox

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Re: Sheepscot Turntable - Official Work Thread
« Reply #16 on: January 11, 2016, 02:32:48 PM »
The problem with boiler tubes, is they are weak and subject to collapsing or bending. Many of the two footers used solid wood poles, just like the standard gauges because of the rugged durability of them.

A boiler tube with a hollow core may work in ideal conditions, but in the cold, when bearings are stiff or as things shift over time or a not quite equalized load, and the hollow pole will bend.

Carl Soderstrom

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Re: Sheepscot Turntable - Official Work Thread
« Reply #17 on: January 12, 2016, 03:21:01 AM »
Has anyone else seen where there was a square cast pocket at an angle
bolted to the table, then a 4X4 (or 5x5?) was shaved down with a draw knife
or turned to a manageable diameter? I think the square end was cut at a bevel
to get the max wood in the socket.
The wood was Oak, or maybe Maple.

Paul Uhland

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Re: Sheepscot Turntable - Official Work Thread
« Reply #18 on: January 12, 2016, 05:31:26 AM »
The "Downey Engineering Consultants" are  invaluable WW&F members.
Their design knowledge, casting formwork,  pilot assembly, coach brake mods, whatever they do, is totally excellent.
Fascinating to follow progress of what they do.
Can't wait for 11's fabrication.
Paul Uhland

Brendan Barry

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Re: Sheepscot Turntable - Official Work Thread
« Reply #19 on: January 15, 2016, 12:46:03 AM »
Some pictures of the original Wiscasset turntable. The original turntables did not have a continuous ring rail at the outer edge of the turntable. There is a continuous inner ring rail under the center of the turntable that forms the bearing assembly the turntable spins on. The outer ring rail is only present where tracks connect to the turntable bridge. In the pictures of the Wiscasset turntable the "pit" originally had a timber retaining wall that was later replaced with concrete. The Albion turntable had nothing around the pit area just the ground sloping into the pit area. Our turntable at Sheepscot will have concrete bulkhead with a piece of ring rail in front of the roundhouse and turntable lead area. The rest of the turntable area will be open like the Albion turntable pit.

You can see the outer ring rail ending past the the last track in the foreground.



You can see the wheels holding up the turntable on the inner ring rail in this picture.



The earlier timber retaining wall.



Albion turntable.



« Last Edit: January 15, 2016, 12:48:32 AM by Brendan Barry »

Wayne Laepple

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Re: Sheepscot Turntable - Official Work Thread
« Reply #20 on: January 15, 2016, 01:22:44 AM »
I have a couple of questions about the turntable plan. I notice in the photo of the Albion turntable that the rails on the table are laid on timbers parallel to the rails rather than spiked directly to the ties. In looking at the Wiscasset turntable, it's not obvious if that is the case. So that's my question: timber or not? Also, at the points where track emanate from the turntable, is there some sort of "shelf" on which the frame of the turntable would rest to absorb some of the shock of the locomotive entering or leaving the turntable, or do the outer wheels and the ring rail handle all that?

Brendan Barry

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Re: Sheepscot Turntable - Official Work Thread
« Reply #21 on: January 15, 2016, 01:28:42 AM »
Wayne the rails are laid on parallel timbers like the Albion turntable. The turntable sits on the outer ring rail when your coming on of off with a locomotive.

Mike Fox

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Re: Sheepscot Turntable - Official Work Thread
« Reply #22 on: January 15, 2016, 01:38:08 AM »
I find it interesting that there is a fence across the doors to the Albion Engine house. This is a post abandonment picture. Suppose this was to keep animals in?
Mike
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Jason M Lamontagne

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Re: Sheepscot Turntable - Official Work Thread
« Reply #23 on: January 15, 2016, 12:11:14 PM »
Somewhere we have a photo of the Wiscasset table w 7x9 rail runners (Harold called them sleepers) laying flat under the rail.  This is as the PoCo drawing shows; in fact the Wiscasset table appears to be exactly like the drawing while Albion may be a little different.  Ours is per the drawing- except that the inner and outer wheels were made a consistent diameter (instead of an 1" different) to eliminate a pattern.

Answering Wayne's question another way- there is an outer ring rail to catch the edge of the table as equipment rolls on; what we're saying is that the outer ring rail is not a full circle; it exists only where tracks enter the table.  That partial ring rail is on concrete- one may view that concrete as equivalent to a bridge abutment.

See ya
Jason

Mike Fox

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Re: Sheepscot Turntable - Official Work Thread
« Reply #24 on: January 15, 2016, 01:37:26 PM »
Complete circle of cement I hope. That would do two things. Look like Wiscasset, and also prevent movement from frost pushing against the back of the wall, making it lean to the center, causing a big problem over time
Mike
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Jason M Lamontagne

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Re: Sheepscot Turntable - Official Work Thread
« Reply #25 on: January 15, 2016, 01:50:04 PM »
The current plan is not a full circle- Wiscasset only had a full circle at the end and looking closely, it was merely a retaining wall with no where near enough strength to hold the 'abutment.'  A close look also shows that the 'abutment' and the retaining wall weren't even connected.

We've considered connecting the center pour and 1/4 circle outer pour with 2 vertical contrite ribs- that would address the tipping problem.  We're not too worried about it with the new plan for how to pour- but it's on the table (we can talk in person).

Our new view is that a full outer circle of concrete, large enough to he structurally effective, would not be historically correct and would use dozens of yards of concrete unnecessarily (equating to $1000's).

See ya
Jaso
« Last Edit: January 15, 2016, 02:55:44 PM by Ed Lecuyer »

Gordon Cook

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Re: Sheepscot Turntable - Official Work Thread
« Reply #26 on: January 15, 2016, 03:22:07 PM »
Further observations:

In Albion the ground around the turntable where you had to walk to push the turntable around looks pretty uneven.
That would make it very difficult to turn the engine, especially in cold weather with snow and ice. I bet shoveling out the turntable pit was a real treat.

Also, on the post abandonment pictures taken at Albion, it looks like there was a wood beam added between the two queen posts.

Something else that I have been pondering about the truss turntable design:
As Harold explained, once the engine is centered the center pivot has all the weight. Without a continuous ring rail that would make putting the engine in just the right place very important!
Are there any tales of turntable mishaps?



.
Gawdon

Greg Klein

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Re: Sheepscot Turntable - Official Work Thread
« Reply #27 on: January 15, 2016, 03:39:25 PM »

Something else that I have been pondering about the truss turntable design:
As Harold explained, once the engine is centered the center pivot has all the weight. Without a continuous ring rail that would make putting the engine in just the right place very important!
Are there any tales of turntable mishaps?



.


  In related musings, do the ring rails "ramp up" or have a beveled edge to facilitate re-railing of the edges of the turntable? I imagine there is some horizontal play even with a perfectly balanced load.

Jason M Lamontagne

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Re: Sheepscot Turntable - Official Work Thread
« Reply #28 on: January 15, 2016, 03:44:18 PM »
This design of table actually makes placement less critical.  The inner ring, which takes nearly all the weight (the rest by the center pivot)- once the equipment CoG is within the 11' inner ring circle, the outer ring is unloaded.  It is very forgiving. 

Jason M Lamontagne

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Re: Sheepscot Turntable - Official Work Thread
« Reply #29 on: January 15, 2016, 04:05:43 PM »
We believe we can contour the ground arojnd the circle so the height transitions are easy and not extreme.  As far as cleaning the pit- a closed pit w a ring rail requires jumping in and shoveling out no matter what- to clear the ring rail.  This open pit, w no full outer ring- there's usually no need to shovel, and if there is, you can get in w a tractor to clear snow.

There is a little ramp on the ends of the partial outer ring rail- but the procedure should be:  don't attempt to turn unless the outer wheels are completely off the outer ring rail.  That proves there's no load on it. 

The table trusses will be taken up so that the table will sit off the outer rail when weight is centered on it.

We are VERY excited about this partial put idea-  at least I am- because it's only possible w this particular table design.  This design was common on Maine 2-footers and other smaller, older lines.  The open pit design is a way of showing the way these tables were usually set up.

See ya
Jason