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Sunday, February 28, 2016

OHSU Tram

OHSU Tram approaching (or is it leaving?) the upper terminal.
Spent some time wandering around OHSU a couple of days ago. It's a very weird place, full of winding halls and secret labs. Okay, maybe not secret, but secure, authorized-personnel-only kind of places. We walked into Jackson Hall on the ground floor, took a walkway over to the main hospital and had to go down six flights of stairs to get to the cafeteria, which was on the third floor. It's a very weird place, and the tram is one of the weirdest things there. 

 
OHSU Aerial Tram Upper Terminal
The OHSU Tram is a huge, in-your-face, mechanical engineering / construction project. Conceptually simple, we have a couple of cars hanging from wires that get sent back and forth from the bottom of the hill to the top.
    The actually mechanics are a little more complex. It has has two cable cars, each with their own pair of support cables. They share a single drive cable. When one is going up, the other is going down. The up and down portions of the drive cable are separated by about 30 feet. Inside the terminal both sections of the drive cable go over large wheels and disappear into the floor. Where do they go from there? The simplest solution would be for the incoming cable to down through the floor, around a very large wheel and then up through the floor again before making a 90 degree turn over the regular large wheel and heading back down. But where is that very large wheel? It's not open to the public, why would they want to see it? It's just nasty old machinery after all.
     I spent an hour walking around, looking at stuff, and I couldn't quite sort it out in my mind just how all this stuff fit together. The crazy angles and elevations don't make it any easier. But now that I see this picture I think it's fairly obvious that the very large wheel is there and it is inside the yellow-green box.
    The top end terminal is essentially an idler pulley, all the drive machinery is at the bottom end. Since the bottom station is at ground level, and the drive cable there disappears into the floor as well, I surmise that the drive motors are in a concrete pit, especially excavated for this project.
    I don't know what the red box is for. I think the architects just wanted it there.

The street in this picture is a moderately steep hill. We are looking downhill. You will notice that to the left of the yellow-green box there is a concrete column. It contains a stairway and an elevator. There is also a walkway stuck on the side of it that connects to this road. Walking up this hill in the bike lane, we came upon this, and since the tram is a powerful attraction, we summoned the elevator, and lo and behold, it came. I wonder if anyone else ever uses that entrance?

A different view of the mysterious red and yellow-green boxes, taken from the walkway mentioned above.

Cable stuff at the upper terminal.
The spools of wire in the left center of the picture are the ends of the support cables for one car. You can see the bottom edges of the spools for the other car in the upper left. The drive cable goes over the two large, yellow, spoked wheels. The closer one is obscured by a grate in the upper right corner of the image. The other is hiding behind a pole just to the right of the far    support cable spool. The closer drive cable cuts through the center of the picture from top to bottom. The upper half of this segment goes through a black tube about six feet long. I think it might be a speedometer, though how it works I haven't a clue. The drive cable on the far side is partially visible as a thin black line in the bottom center of this photo.

The tram was designed by Angelil/Graham/Pfenninger/Scholl and built by Doppelmayr CTEC. Williams & Dame negotiated the deal.

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