Frank, thanks for that additional information and photos. It is all very helpful. I am going to come back to you when I reach the platform stage on the towers to get your opinion on the appropriate number of cables. I just cannot decide at this point.
I have determined though the the towers should be 5" x 6" so that will have some decided effect on the size of the sheaves and the number of cables. One other consideration to take into account is the fact that the four sheaves on each tower do not sit on a single platform. The “platform” at the top of each tower is actually a set of four girders. The left side sheaves sit on one girder and the right side sheaves sit on a separate, parallel girder, so space is limited.
The CMR bridge main span is 4 3/4’’ wide. The hoist platform is 5’’ wide x 1 1/2’’ and it holds the 16pieces for the sheaves, the motors, gears and the shack, along with a three sided railing. So if You were to make yours 5’’ wide and 4’’ long, you would have more than enough room to put anything You want up there. Remember…part of the sheaves overhang the edge on both sides so the cables do not rub on the structure. Look at the pic’, you can see how they overhang. The four sets on Your bridge should do the same.
I’m sure there must be at least a partial floor on the hoist platforms…it would be awful dangerous to do any maintenance on moving parts, if you just had girders to walk around on.
Don’t start over thinking…
Take Care! [:D]
Frank
EDIT: This pic’ should give You a better shot of the sheave overhang:
Yes, I agree that the sheaves should overhang the platform to allow cable clearance, and I plan to do that. There is a lot to think about in the planning stage, so I appreciate the reminder.
I’m not so sure about the partial floor on the hoist platforms. From the photos available of the PRR bridge/towers, and the overhead views using Google Maps, it certainly appears that the sheaves are mounted on girders with no floor across the top of the tower. I could be mistaken here, but it sure looks like what I have described. I will need to researching this further.
I am concerned about space limitations up at the top of the towers, and cost becomes an issue as well. Those sheaves are $3.50 a pair, so if I wind up installing 4 cables on each sheave, that would require 16 pairs of sheaves for a total cost of $56.00. That seems excessive just to complete the sheave portion of the project. I have considered scratchbuilding the sheaves to save mon
If cost is Your concern, take a look at this Plastruct link and on page 37 for Handwheels/Disc’s. You could make Your own sheaves with a spoke on the outside and disc. in the middle, followed by another spoke and so on. Should be a lot cheaper than the Tichy parts. And No…I would not try to make them out of thin styrene, not when there are offerings already out there. Cutting a round disc from sheet styrene is pretty hard to do and cutting from a tube isn’t so easy either.
If you found a thin-wall corrugated tubing, then stuffed it with these gear hubs, maybe with the teeth sanded off you might get a neat looking assembly. Or you could wrap them with grooved styrene sheet cut into a strip. Put the joint at the bottom, out of view.
Frank, I just received an order in the mail yesterday from Tichy (via eBay) consisting of Rivet Plates. These are 1 1/2’ x 2 1/2" sheets of styrene filled with dimple marks representing rivets. I will see how this works out on the tower construction.
Yesterday, I finished installing the top and bottom lacings. Today, I will finish the top x-bracing, and that will nearly complete the bridge except for some minor finishing touches.
I remember being at Bridge One in the Cleveland Flats one July Fourth. I was friends with the operator. He gave us a ride to the top of the towers to watch the fireworks at nearby Edgewater Park!
That was some times to remember! Below is a look at the present-day “Bridge One”
Part of the original bridge, Mike. It was built in 1956. Before that the NYC’s New York-Chicago main line crossed over the river on a swing bridge with a gauntlet track, effectively bottlenecking the four-track main down to one (can only use one gauntlet at a time!) The PRR used the same bridge to get to the ore docks where the Hulett unloaders used to work. Today it is NS.
On May 8, 1974 the counterweight of the open bridge was struck by Penn-Central eastbound train OV-8 at about 35 mph. I was there a few hours after it happened. Not a good thing to see.
Thanks, Mike. I like to enlarge the photos to find flaws and then fixed them. On the other hand, the camera sees what the human eye often does not see, so enlarged photos can be scary to the modeler who has worked hard to build a flawless model.
