Sheepscot Turntable - Official Work Thread

[Jason M Lamontagne]

None to be had- after the wheels were completed,  our volunteers focused on bridge construction, ring rail bending and center pivot machining.  We outsourced the bending and drilling of the rolled frame components of the spider; those parts haven't yet arrived.  We hope to start making spider axles this week or next.

See ya
Jason

[Chuck Watford]

Thank you. I look forward to seeing photos as the spider goes together. From the drawings, it appears that the wheels at either end of the bridge will be mounted with off-the-shelf pillow block bearings?

[Carl G. Soderstrom]

Two things: (for now)

Should not the female side be fastened to the bridge and the male to the foundation to keep water
from pooling and freezing in the pivot? Or will there be a seal to keep water out

Was mentioned on Book of Facades - no grease fittings because could not get to it -
a 3/16 copper line (or 1/8 black pipe with a zerk at outside of bridge timber would do the trick)
That would require the set up as above.

Or drill a hole alongside the pivot and add  zerk so you can grease between ties
A short nipple can be tack welded on so the zerk is below tie level.

Or I am seeing problems where non exist? But it is easier to do it now.

[Mike Fox]

Should not the female side be fastened to the bridge and the male to the foundation to keep water
from pooling and freezing in the pivot? Or will there be a seal to keep water out

I asked that very question last week off line. I was told there will be a drain hole in the female portion.

[Robert Hale]

Two things: (for now)

Should not the female side be fastened to the bridge and the male to the foundation to keep water
from pooling and freezing in the pivot? Or will there be a seal to keep water out

Was mentioned on Book of Facades - no grease fittings because could not get to it -
a 3/16 copper line (or 1/8 black pipe with a zerk at outside of bridge timber would do the trick)
That would require the set up as above.

Or drill a hole alongside the pivot and add  zerk so you can grease between ties
A short nipple can be tack welded on so the zerk is below tie level.

Or I am seeing problems where non exist? But it is easier to do it now.

I think this would be the best long-term solution to solve a few problems, first being that over time when the pivot is greased it will displace any water and not allow water to collect in the pin pockets, and when the grease overflows onto the plates it would be a rust preventer as well. My .02

[Benjamin Campbell]

I too had questioned the placement of the male and female bearing components seeing advantages to both arrangements. The advantage of the current arrangement is that the cup bearing will hold oil/grease nicely.  On the other hand - in addition to the possible retention of water I can envision wind driven sand working its way in there creating an oil/sand grinding compound.

Of more concern to me is the use of relatively fragile gray iron for the central pin bearing - it would not take much a shock to snap it. A welded steel center pin should be easy to fabricate – possibly with material on hand – and be much stronger. Just my .02

[Robert Hale]

I too had questioned the placement of the male and female bearing components seeing advantages to both arrangements. The advantage of the current arrangement is that the cup bearing will hold oil/grease nicely.  On the other hand - in addition to the possible retention of water I can envision wind driven sand working its way in there creating an oil/sand grinding compound.

Of more concern to me is the use of relatively fragile gray iron for the central pin bearing - it would not take much a shock to snap it. A welded steel center pin should be easy to fabricate – possibly with material on hand – and be much stronger. Just my .02

I think the center pivot is just that, a pivot in this case that would not see any real load to break the pin off. The spider wheels look like they will take the brunt of the forces on the turntable while loaded. As far as the grease, if you pumped 2-3 full tubes of grease into the pivot it would build up a thick wall of grease in the area and keep everything out, sand, water, rust.

[Mike Fox]

Center pivot is just a guide, no load.

[Benjamin Campbell]

We are probably fine but “safety first” is the motto of railroads and heavy industry in general. While there is no vertical down load I would think there would be some horizontal load while breaking the engine etc – especially were we to run the engine past center accidentally . Given that our bearing wheels are unflanged we are relying solely on that center pin to keep the ‘bridge’ on the wheel/roller assembly.

We are probably fine but I grew up in a family of architects where such matters were always considered and debated. I have seen so much broken/repaired cast iron in my collecting of old machinery and career as an antique dealer that I tend to be weary of relying too heavily on it for critical applications.

[Alan Downey]

Due to the presence of the bearing pivot wheels and the slack in the bore for the pivot center, the only possible loading of the center pivot "pin" is shear. It's 4" in diameter. Using very conservative numbers for the yield strength of cast iron, there would have to be a shear load well beyond 100,000 lbs to break it. While I understand the gut reaction to cast iron from antiques, it was heavily used as a structural material, and is appropriate for this application.

[Robert Hale]

Due to the presence of the bearing pivot wheels and the slack in the bore for the pivot center, the only possible loading of the center pivot "pin" is shear. It's 4" in diameter. Using very conservative numbers for the yield strength of cast iron, there would have to be a shear load well beyond 100,000 lbs to break it. While I understand the gut reaction to cast iron from antiques, it was heavily used as a structural material, and is appropriate for this application.

Given too how the pin was machined with a radius on the transition it eliminates any stress risers at that shear point, and given the better quality of cast iron now I agree that it is a non issue.

[Benjamin Campbell]

Sounds good. The center pin looked smaller than 4 inches in the photos.

[Carl G. Soderstrom]

As long as the drain hole does not freeze shut everything will be sort of OK.

A rubber skirt will keep out most blowing sand & snow.

It is not like it will be used multiple times a day 7/365

[Paul Crabb]

     In my post of Sept 16 (pg22) I asked if the lower rails for the turntable bridge had been bent and if so were they bent on-site or sent out. I can't say that in subsequent posts that my question has been answered so I'm asking it again.
     Additionally when working on the lower rails on the 10th we tried to use the hydraulic porta power to bend the rail by backing off the screw on the rail bender so that the hydraulic cylinder would fit between the head on the rail bender and the rail. However, we were unable to do so as some of the treads on the screw of the rail bender are damaged thus preventing us from backing off the screw enough to fit the hydraulic cylinder.

[Dwight Winkley]

A Posting on WW&F Facebook, Sept 15th said two rails for bottom of turntable and two rails for bearing  pedestal. Four rails were bent.  So all rails for the center of turntable have been bent on site.