Note the trunnion is held up high on an A-frame.
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| Photo taken by Mapio via BridgeHunter, License: Creative Commons Attribution (CC BY) Also, Douglas Butler post The Carolina Rail Services Railroad Bridge is an Overhead Counterweight Articulated Trunnion Bascule Bridge formerly use by Beaufort & Morehead Railroad in Morehead City, NC crossing the Newport River. |
This patent drawing is when I noticed that this design has a high trunnion.
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| Google Patents via BridgeHunter, cropped, License: Creative Commons Attribution (CC BY) |
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| Bill Lovick posted The Old M'City - AB Bridge at 26th Street Douglas Butler shared Credit to Bill Lovick Morehead City Ab Bridge on 26th Street in Morehead City, NC. |
This view shows that the bridge is powered by a fixed pinion against a circular rack that is under the counterweight support arm. It also shows that the bridge is so close to the water that it blocks even rowboat-sized boats. As a bonus, this video follows a Fairbanks-Morse opposed-piston locomotive.
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| 19:28 video @ 10:04 |
The above video shows that when the bridge is down, the link between the top of the A-frame and the bottom of the counterweight is not horizontal. That means as that member goes past being horizontal, the distance between the plane of the counterweight and the frame shortens as the distance between the center-of-gravity of the span increases. So this design does not remain balanced and the motor will need increasing horsepower to shove the span down.
Another view of the rack when it is in the raised position.
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| Lorelei IV Blog via BridgeHunter, scroll about 2/3 of the way down, License: Creative Commons Attribution-NoDerivs (CC BY-ND) |
There is some serious shipping in this area.
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| Street View, Jul 2022 |
This is one of three ships in the blog. I copied this one because this is one of the few times I have seen the cranes on a ship being used. In the photos I normally see, they are swung out of the way because the boat is being loaded with grain.
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| Lorelei IV Blog via BridgeHunter, scroll about 2/3 of the way down, License: Creative Commons Attribution-NoDerivs (CC BY-ND) |
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| Douglas Butler posted From Mapio.net. Detail of an Overhead Counterweight Strauss Type with the curved rack in Morehead City, NC near Radio Island. |
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| 1:38 video @ 0:11 |
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