Walthers Bascule Bridge

[Anonymous]

OK, folks, I'm working on a pair of Walters Bascule Bridges (#933-3070) that are going to be set end-to-end to open for a doorway. I have a few questions for folks who have worked with these bridges before:

1. How the heck have you managed to get the motor switches to work properly? Near as I can tell, the switch is supposed to maintain contact until tripped by one end or the other of the ratchet beam, but it sure doesn't seem to want to do so without a hand there holding it in contact.

2. What solutions have folks found for maintaining conductivity between the lead-up rails and those on the draw-section of the bridge? Wire jumpers? Spring contacts?

3. Has anyone found a good way to keep two bridges in line with each other without using a central pier? The instructions mention that it is possible with "slight modification," but don't go into it beyond that.

Thanks,
Jessica

[Anonymous]

Jessica,

I do not have this kit, although from the outside of the box and the review in MR it looks great. I just can't afford it right now against other things I need.

Because I don't have the kit you should take what I have to say with a grain of salt ... Another type of switch you could try is a mercury switch. You can get these at Radio Shack or other places. The problem is that it will likely need to be installed in another location in the kit; possibly hidden in the counterweight. Then you will have the problem of hiding the wires which go to the switch. Mercury switches have a small dab of mercury in a tube with two fillaments. When the switch is tilted far enough the mercury flows to the other end opening the switch by breaking contact with the fillaments. There are other ways or doing this, but I think this is worth checking out.

As for part two, I think feeder (or jumper) wires are your best alternative. Unfortunately, you will have to hide these as well.

Finally, I think it will be Very difficult to hold the bridges in position without some external support like a central pier. I design bridges for a living and I cannot think of any bascule bridge of this type with two sides and no central pier. It is possible but very unlikely because there are other more economical ways to get over a channel. The biggest problem I can think of in real life is that when a train is approaching from one side, how does the bridge not deflect excessively on one side so that it permits the train to pass from one side to the other without an excessive bump.

I can think of some possible ways to overcome this but I would have to be able to put my hands on the kits to see exactly what is going on. I would also have to know what you were willing to compromise in appearance to achieve this.

I would supply a false pier of some kind which you would use when the railroad is in use but stored out of the way at other times.

I am still working out my layout plans since I am trying to find a new house with a basement for railroading. One thing I am considering at the doorway is a cosmetic trestle concealing a board across the doorway. The back of the door would be painted (or a poster) to look like the James River in Richmond VA. There is a double track trestle on the CSX (formerly C&O) running parallel to the James for quite a streach and I would try and disguise the (probably 1 x 4) board to look like this trestle by glueing Micro Engineering 50 ft plate girders to the near side. Whenever I thought I was 'safe' in the choo-choo room, I would close the door and set the board over the gap. If I were worried someone may come in without knocking, I would just set up the board but leave the door open. I might even paint safety stripes on the other side to keep someone from running into the bridge.

I hope you can solve the problem to your satisfaction. Good Luck - Ed

[Anonymous]

Ed,

Thank you for your comments. I had not realized that prototypes relied upon a central pier as well. That said, I think I can rig a fairly simple solution. I can have hinged plywood panels that drop away from the opening when it needs to be opened, with a pier mounted on one of them and with the surfaces covered with water texturing. This takes care of my problem #3. #2 is going to be pretty easy as well, using hidden jumpers. #1 is still going to be a bit of a pain, but frankly, I'm tempted to scuttle the whole original setup and manually control the motor from a dedicated transformer, rigging it with some nice, prototypical signal light to let me know when it is in position.

[Anonymous]

Jessica,

I didn't realize the lifting switch was so tempremental. I think you could use an atlas controler or twin to connect the bridge moters to a power pack the same way you might hook up a turntable. I would also consider a light which came on at the control panel when the bridge is not fully seated on the pier.

As for the pier, I have a copy of the book Model Railroad Bridges and Trestles, published by Kalmbach ($16.95). There is a bit on bascule bridges in there; specifically, on page 143 you may find a plan view drawing of a bascule bridge. I like the pier detail which shows two large cylinders of concrete connected where the two sides of the bascule trusses rest. All I would do for your situation is increase the diameter of the cylinders since you will have two spans resting on the pier. This would provide adequate room for all the bearings.

Your idea of providing a waterscape below the bridge is nice because it provides you with the opportunity to add much scenic intrest. Others have much more to offer on creating a good water scene. I would like to point out a nice extra detail for bridges at narrow navigable channels: dolphins. A dolphin is a barrier used to protect piers from scrapes with boats/ships. They are most common in narrow channels where barges are frequent. The span of the Walthers Bascule bridge is just right for these. The most common type of dolphin I have seen is a group of ten to fifteen wood piles driven in a group to protect the nose of the pier (both ends are protected with a seperate dolphin each). The piles are driven in a circle with a 1 to 12 batter so they all meet in a tight group about eight feet above the waterline. Without the water they would look something like a tee-pee. The whole group is then tied together with rope or cable for a distance longer than twice the diameter of the piles. There is a swing span bridge in West Point, Virginia with these type of dolphins protecting the central pier. Of course the piles are nearly rotten and covered with barnicles in the splash zone.

One other little idea, I would run the guard rails long on one side of the central joint so they rested on the deck of the other bridge. If you are careful, this could be helpful in holding the two bridges in line when they are down. Just make sure the 'long' span doesn't come down first.

Good Luck - Ed

[Anonymous]

Jessica,

Have you seen the Walthers model of a swing span bridge? If these guys don't stop making such interesting bridge models available, I'm going to go broke. Isn't capitolism great!

Ed

[sumpter250]

Jessica,
Like Ed, I don't have the kit, and am relying on the MR product review. Electricly, the UP and Down limits are easily done. Mechanically, I would have to have one of the kits built to figure out the best means of activating UP and DOWN limit switches. So! The motor is operated by a DC power source, through a reversing switch.
If two micro switches are wired into the motor circuit, with the "commons",one to each side of the reversing switch, and the NCs,one to each side of the motor,
if either switch opens, the motor stops. A diode from the NC to the NO contacts will allow reverse current to flow until the switch goes back to the closed position, and the motor continues to run until the opposite switch opens.
The problem with this,(and with your'signal light')is mechanically operating the limit switches. The motor has to stop before the bridge reaches the mechanical limit of its travel,or there will be gear crunching. I wonder if one of the automatic reversing circuits like those used for point to point trolley operation could be modified to operate the bridge. Again, detecting the UP, and DOWN positions........most critically, the down.
If the bridges could be operated by cable, with the drives under the layout, the mechanics would be much simpler,and easier to hide.
There is, of course, the simplest method,,if the bridges are only lifted to permit access to the area,they could be moved by hand. No stripped gears,positive alignment in the down position.....
Maybe in pondering these things a solution will become obvious. Moving the bridge is easy,stopping the bridge where you want it to stop, that's the hard part.
Pete