Track fiddler The bridge is really coming along and looking excellent Rich. I can hardly wait to see it finished and a picture of it on your layout, hopefully. Now get back to work on that thing, I need to see some more progress, you can't just park this thread on page 4 TF
The bridge is really coming along and looking excellent Rich. I can hardly wait to see it finished and a picture of it on your layout, hopefully.
Now get back to work on that thing, I need to see some more progress, you can't just park this thread on page 4
TF
However, I am about to install handrails around the sheave platforms up at the top of the towers. And, I need to fine some suitable chain to hang from the towers to the underside of the counterweights. These chains are used on the prototype to balance the added weight of the pulley cables.
I still face a big task in terms of installing the bridge and towers on the layout. At the moment, I have a 30" wide open space on the layout that the bridge must span. Trains run over a temporary plywood sheet that spans the open space. That 30" wide open space needs to be further opened to accomodate the towers.
So, I have some sawing and trimming facing me before I can complete the installation of the bridge and towers on the layout.
Stay tuned.
Rich
Alton Junction
My son Steve has been working on one to be apart of a rolling section that when the layout is being run would be put in place.
mbinsewi Looking good Rich . I didn't realize that the actual lifting was done at the control house, and the big sheaves on top were just part of the counter weight set-up. Have you found something decent to use as the cable? Mike
Looking good Rich .
I didn't realize that the actual lifting was done at the control house, and the big sheaves on top were just part of the counter weight set-up.
Have you found something decent to use as the cable?
Mike
The cable (red) that is strung over the sheaves up on top of the tower platform connects the bridge to the counterweights. On the prototype, there are 16 cables running over each pair of sheaves, for a total of 64 sheave cables.
The cable (blue) that is strung over the pulleys on the bridge is a single cable. It connects near the top and the bottom of the tower.
Currently, the bridge is raised and lowered from a remote location 3 miles north of the bridge. But, for many years, the bridge was raised and lowered by the bridge tender in the shack on top of the bridge. The system is powered by two 220-volt, 300 HP motors inside the bridge tender's shack. The motors rotate the four pulleys located just outside the bridge tender's shack, which is turn rotate the other eight pullleys via the cable.
As the pulleys rotate, the bridge responds by raising or lowering as the counterweights provide balance in the form of equalizing the loads. So, in effect, the bridge itself and the counterweights do the heavy lifting with the sheaves acting as a sort of fixed fulcrum.
With all the pictures in the link that Ed posted, I had to look through them until I found the cable and sheaves along the top of the bridge, and then I seen the picture with the two huge pulleys on each side of the control house.
Mike.
My You Tube
Yesterday, I added supports to the tower platform walkways and, more importantly, I added the 12 pulleys on the bridge. There are 6 pulleys on each side of the bridge. Four pulleys are located around the bridge tender's shack, four more pulleys are located mid-way on the top of the bridge, and four pulleys are located on the ends of the bridge.
I want to thank mobilman44 for generously providing the 12 pulleys which are actually wheels from a Sherman tank kit that he built. The 12 wheels were surplus parts from the kit. The wheels are perfect as pulleys with their 5-spoke configuration and size. I still need to cut grooves in them when I add the cable.
My plan is to add the cables at a later date after I install the bridge and towers on the layout. But, first, I need to cut out some plywood and framing to properly position the bridge and towers. Once the bridge and towers are in their final position, I can string the cables. I also need to add handrails up on the tower sheave platforms.
This project has now consumed 6 weeks of my time, so I am going to take a break before actually installing it on the layout. Besides, my golf clubs are calling for me now that Spring has finally arrived in the Chicago area.
Here are some near-final photos of the whole setup, absent the cables. I am also including a diagram that illustrates how the cables are connected to the pulleys sheaves and counterweights.
Thank you all for your interest, advice, and critique on this project.
mbinsewi richhotrain . Scratchbuilding is not for the timid because there are no plans, I'll tell ya Rich, I'm follow a plan, from the MILW. Engineering Dept., for my little terminal caboose scratch build, and to me, it seems harder, trying to keep all the dimensions right. Mike.
richhotrain . Scratchbuilding is not for the timid because there are no plans,
I'll tell ya Rich, I'm follow a plan, from the MILW. Engineering Dept., for my little terminal caboose scratch build, and to me, it seems harder, trying to keep all the dimensions right.
richhotrain. Scratchbuilding is not for the timid because there are no plans,
toptrain I like the work being done on this lift bridge. It is high quality work.
I like the work being done on this lift bridge. It is high quality work.
It is not museum quality by any means, but I am doing my darndest to make this bridge and towers look good. Scratchbuilding is not for the timid because there are no plans, no instructions, no tight fits, no interlocking parts.
Thanks again.
Rich,
You do not have to add any grooves to them. As long as they have covers to protect the cables. Use the covers in the appropriate thickness of the cable you will use and notch out on the inside of the covers where they go over 1/2 of the sheeve to hold the cables in place. On the sheeves of the CMR bridge, they do exactly that. The cables don't go around the sheeve, only have way up, with built in notches on the center spacer sheeve, which is a little smaller in diameter, along with the notches, than the two outside ones. Use the covers you will make for a similar arrangement. This photo should show you what I mean:
They are a little blurred, I didn't use My tripod, but You should get the idea.
Take Care!
Frank
I have been back and forth in my own mind about how to "string" the cables over the sheaves. Since the bridge will not be operational, there is no risk of lateral cable movement in the absence of grooves on the sheave rims.
And, as Ed has pointed out and illustrated with photos, you cannot see the grooves since the cables are banded together at the top of the tower, and the sheaves are covered with metal "roofs". In fact, if you use Google Maps to view the bridge from above, the sheaves are not even visible.
So, while I would like to reflect the prototype as much and as accurately as possible, I am not sure that adding grooves is necessary.
At the moment, I am also uncertain as to how many cables will be strung over each sheave. On the prototype, there are 16 cables on each sheave, a total of 64 cables on the two towers. No way can I string that many cables on a 1/2" wide sheave unless I use human hair. LOL. I am thinking, 3 or 4 cables maximum per sheave.
As Rich mentioned, the sheave/flywheel originally had grooves but he was unable to capture the thin section in the mold so he already wrapped it with styrene.
Sheave-width by Edmund, on Flickr
Actually, the Canal Street tower sheaves have a sheet metal guard over them so you wouldn't see any grooves:
Canal_sheave by Edmund, on Flickr
Here's another example of a similar guard. Note the bracing and rivets:
NJ_bridge_sheave-guard by Edmund, on Flickr
It would be a trade-off, modeling-wise. Leave the guards off and show the groovy grooves or stick with accuracy had have the sheaves hidden under guards?
richhotrain I have problems too. When I posted it initially, I did not do anything different, but it does seem to be corrupted. Rich
Not only the MR site, the whole Interweb seems to be wonky today?!?
Cheers, Ed
mbinsewi Notice what, Rich....?? I have been trying to respond to your last post, but when I try, the page is all messed up. Everything you see on the right side, shows up under your post???? I couldn't quote you, or respond. I could respond to any other post in your thread, except for your last one??? I am able to respond, in normal fashion to Dr Wayne's post. ?? This is really strange, I wonder if it has to do with the mysterious page 5, and the goofy page number system in here, when threads get to page 5. ANYWAY! Maybe you could chuck them in a drill and cut grooves? Mike.
Notice what, Rich....??
I have been trying to respond to your last post, but when I try, the page is all messed up. Everything you see on the right side, shows up under your post????
I couldn't quote you, or respond. I could respond to any other post in your thread, except for your last one???
I am able to respond, in normal fashion to Dr Wayne's post. ?? This is really strange, I wonder if it has to do with the mysterious page 5, and the goofy page number system in here, when threads get to page 5.
ANYWAY! Maybe you could chuck them in a drill and cut grooves?
That's a great idea Mike. Maybe one could put a variable speed drill in a vise, taping the trigger on a slower speed and use a very small round or V notch jewelers file..... Maybe
A very small machine thread screw, micro washers and nut to hold the sheave stable in the drill
You're making great progress, Rich.
If you want to give your flywheels grooves to make them more pulley-like, you could use strips of styrene (Evergreen HO scale 1"x2" or 2"x2") or small diameter soft brass wire to replicate the raised portions, using ca to affix either material in place. If you opt for wire, I'd suggest drilling starter holes in a place on the pulley where they won't be seen, ca-ing the end of the wire in place, then wrapping it around the circumference and also ca-ing that end into a suitably-hidden hole, too.
Perhaps a little tedious, but the sheaves will be one of the most readily visible details on the project.
Wayne
zstripe Rich, I was also wondering why You only have two I-beam girders on the top platform under the wide section. Should the wide section where the pulleys rest have four? Two perpendicular to the wide section, then they can extend out some. Then it would look more like the proto and function. Take Care! Frank EDIT: For Your info......Sheeves/Pulleys & Flywheels: The main difference between them is their function. The function of a flywheel is to provide a rotating mechanism more inercia, so it won't be so affected by other forces (Such as friction or gravity). The function of a pulley is to transmit the rotating motion from one shaft to another through a belt.
I was also wondering why You only have two I-beam girders on the top platform under the wide section. Should the wide section where the pulleys rest have four? Two perpendicular to the wide section, then they can extend out some.
Then it would look more like the proto and function.
EDIT: For Your info......Sheeves/Pulleys & Flywheels:
zstripe Rich, I commend You on Your efforts......they look good, But, I have to ask. Those are flat belt pulleys, not cable pulleys. There is no provision for keeping a cable in place so they don't spin off. Are You going to add anything to them? Also it looks like You may have them in too far on the hoist plarform and the cables will rub on the side frame of the tower. Associate Design Engineer........... Frank
I commend You on Your efforts......they look good, But, I have to ask. Those are flat belt pulleys, not cable pulleys. There is no provision for keeping a cable in place so they don't spin off. Are You going to add anything to them? Also it looks like You may have them in too far on the hoist plarform and the cables will rub on the side frame of the tower.
Associate Design Engineer...........
Like all of my construction methods on this scratch build, a lot of the components reman a work in progress. For that reason, I have not yet permanently attached much of anything to the bridge or the towers.
The bridge and the towers superstructure are essentially complete, but the add-ons such as the sheaves and pulleys, the cables and chains, the counterweights, the bridge tender's shack all need further refinements to make the entire structure as prototypical as possible.
Regarding the sheaves, the Chooch master that I used is actually a flywheel, not a sheave. But, I was going for form over function. That Chooch flywheel was the closest thing that I could find to remind me of the actual sheaves atop the PRR vertical lift bridge. Big, bulky, massive, yet small enough to look right in proportion to the tower superstrucures. On the prototype, the cable sheave has grooves to route the cables over the sheave. But, on the PRR bridge, the cables are banded together to run over the sheave.
The banding was done to take uneven pressures of the individual sheaves into account. So, in practice, the grooves are not visible. That said, what is to prevent the banded cables from slipping off the rim. Answer: the rim has raised sides to contain the banded cables. So, I have to work that out in terms of finalizing construction.
Regarding the unimpeded vertical drop of the cables without rubbing against the sides of the towers, Frank is right. On the prototype, the sheaves usually extend slightly over the edge of the towers for this purpose. In finalizing the location of the sheave mounts on the tower platforms, I will need to take this into account. What I may do is either trim the bottom mounting plates or drill holes through those bottom mounting plates. I still need to think that through. The following photos show the cable drop from the sheave on the PRR bridge. It appears that the sheave does not extend over the edge of the tower and that the cables drop through an opening in the bottom of the mounting plate.
Frank, keep up your excellent critique. You are earning your pay!
Notice the overhang.....
This photo is a little blurred, but you can see the cables are well away from rubbing on the towers:
I hope that Mel chimes in here because he is the resident forum expert on resin casting.
Alumilite is the source for my resin casting. The company makes a variety of products, one of which is Amazing Mold Rubber.
https://www.alumilite.com/products/mold-making/amazing-mold-rubber
I use this product to make the rubber mold master in which the sheaves are then cast in resin. The rubber mold is made from a liquid rubber mixed with a catalyst to produce a flexible rubber mold. It takes about 8 hours to get a truly usable mold as a result of curing.
The casting resin is made by mixing equal parts of a resin casting material which is poured into the rubber mold and hardens in about 20 minutes. This is the resin mix that I used which is one of several different resin mixes available from Alumilite.
https://www.alumilite.com/store/p/665-AlumiRes-RC-3-Tan.aspx
So, in theory, I should be able to make the 8 sheaves in 160 minutes, that is, 2 hours and 40 minutes. In practice, however, it takes a bit longer. The idea of resin casting seems simple, but it can be quite complex depending upon the size and shape of the item to be cast. I literally had to make 19 castings to get 8 good and usable sheaves.
The 8 sheaves at the bottom of the photo are the finished product that I used. The reason for so many failures is attributable to a couple of factors.
For one thing, the Chooch flywheel which I used to make the master is not a well finished product. Rather, it is finished on only the face side, not the back side, and the rim of the flywheel is imperfect. So, this affects the quality of the casting.
For another thing, the rim is thin and that results in a master rubber mold in which the liquid resin does not always fill the entire space. The result is a resin casting with gaps that would need to be filled before painting. So, I needed to thicken the rim by wrapping a 0.020" styrene strip around the rim. That worked to provide a larger space for the resin to penetrate. But, I wound up making three rubber molds before I got the one that I used as the master.
Thanks Ed. I will definitely check this out.
Track fiddlerI could very much appreciate a lesson like that.
https://www.smooth-on.com/howto/basics-mold-making/
Alumilite is another popular brand of mold-making products:
https://www.alumilite.com/store/pg/21-How-To-Videos-Alumilite-Mold-Making-Casting-Materials.aspx
Bringing in the sheaves, bringing in the sheaves, we shall come rejoicing, bringing in the sheaves
No really. That is really something Rich, Hats off to you. The only thing I ever casted was a silver ring in jewelry class in high school. I remember that and understand that Well.
To cast eight replicas out of a single plastic piece, molded in a rubber casting with resin........... I could very much appreciate a lesson like that.
Track Fiddler
gmpullmanExcellent Progress Rich! Those "top-off" the towers beautifully — Thanks for the updates, Ed
Ditto!!
Dave
I'm just a dude with a bad back having a lot of fun with model trains, and finally building a layout!
Excellent Progress Rich!
Those "top-off" the towers beautifully —
Thanks for the updates, Ed
mbinsewi Those sheaves look great Rich! I've never tried casting anything. So, you used the Chooch sheave to make the mold? Looking great! Mike.
Those sheaves look great Rich! I've never tried casting anything.
So, you used the Chooch sheave to make the mold?
Looking great!
Ed was kind enough to send a spare Chooch sheave to me, and I used it cast the 8 sheaves that I needed.
Mel first got me into resin casting a while back when I needed an alternative to the discontinued Walthers Modulars. But I always struggled with finding an adhesive to join resin cast parts together. With the sheaves, no adhesive is required.