Usually, there're two different bridge shoes. One, where the bridge can move, and one where the bridge is fastened. This way the civil engineers can control the thermic movement of the bridge. For the rails there're devices like the points at a turnout.
Wolfgang
Pueblo & Salt Lake RR
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Just took a really close look at my favorite bridge poster - multi-span deck girder on tall conical masonry piers. One end of each span rests on a steel plate (and is presumably bolted through it to the pier.) The other (upgrade) end rides on shoes. The pier tops are actually stepped to keep the bottoms of the equal-depth girders level.
That's the first time I actually looked at the bridge foundations. Usually I can't get past the trio of thundering, smoke-belching D51 class 2-8-2s.
Chuck (modeling Central Japan in September, 1964)
loathar wrote: About the only pics I can find on the net are of the ME ones.
The Micro Engineering castings (part 80-035) are nice enough and a decent buy for the money I think. You get several per package More pricey but also very nice looking are the bridge shoes from Durango Press, part DP-34. But the most beautiful castings of all, and the most expensive, are the brass bridge shoes from Trackside Specialties/Greenway.
The M-E shoes are the smallest of those three, followed by the Durango Press castings. The Trackside Specialties castings are obviously for a much larger bridge and could be used in S and maybe even O.
A pity you don't live closer to Milwaukee, Loathar, since I bought all three not knowing which one I would actually want to use (turned out to be Micro Engineering) and now I am up to my armpits in surplus bridge shoes. I am the Imelda Marcos of bridge shoes.
In retrospect the bridge shoes are all but invisible unless you take a mirror to the underside of my bridge. But then I am a guy who installed an interior in a caboose that nobody can see inside of ....
Dave Nelson
loathar wrote:Mark-GREAT pics!! Thanks a bunch! It's hard to believe all that weight is focused on those few pivot bolts on the shoes.
Thanks, Loather. The smokey skies caused by grass fires in the area diffused the sun's light. This helped make good pictures by eliminating too-bright areas and dark shadow areas.
A bit of trivia: until before WWII, Muir Station was situated at the east end of the Alhambra viaduct, several hundred yards from conservationist John Muir's home and ranch (more accurately, his rich wife's.) I can imagine wealthy city folk coming here in the early 1900s to enjoy the natural spring waters and baths in Alhambra Valley.
Mark
This afternoon I took photographs of bridge shoes at a couple of bridges on the BNSF mainline in Martinez, CA.
This first is a ballasted deck bridge crossing the middle of an s-curve of the two-lane road. The bridge rests on metal plates. Note the abutment is wide enough for two tracks and the pedestrian tunnel.
The second bridge is a mile or so west and crosses the Alhambra Valley. It is a ballasted steel viaduct. Note that only some bridge ends have "scissors" bridge shoes. A lot of bridge segments rest on plate.
As was mentioned 'way up at the top, short girder bridges may not have fancy shoes. They just rest on a steel plate, usually about the same thickness as the girder flange.
Chuck (modeling Central Japan in September, 1964 - with LOTS of girder bridges)
Sorry to drag up an old post, but searching about for prototype pics of bridges, I came across several that looked like they had no bridge shoes. Are bridge shoes mandatory for all bridges, or do shorter spans sometime not have them? Pic below...don't think this span has bridge shoes, is that right?
dehusman wrote: Take 1x4 and put it across two saw horses. Now put a weight in the middle. What does the board do where it sits on the saw horse? It doesn't go up or down, since its still sitting on the saw horse. What it does is change angle. When the angle changes, that is rotation. If you prevent that rotation (cantilever) the beam you have to design the supports to resist that rotation, even if it is very small. On the other hand if you design the supports to allow a very, very small rotation, then you don't have to worry about those forces (torque). The whole bridge design is simplified and you can figure out the forces in the bridge with relatively simple math and geometry. The anchoring point doesn't have to be some massive structure, it can be a simple bridge shoe.Dave H.
Take 1x4 and put it across two saw horses. Now put a weight in the middle. What does the board do where it sits on the saw horse? It doesn't go up or down, since its still sitting on the saw horse. What it does is change angle. When the angle changes, that is rotation. If you prevent that rotation (cantilever) the beam you have to design the supports to resist that rotation, even if it is very small. On the other hand if you design the supports to allow a very, very small rotation, then you don't have to worry about those forces (torque). The whole bridge design is simplified and you can figure out the forces in the bridge with relatively simple math and geometry. The anchoring point doesn't have to be some massive structure, it can be a simple bridge shoe.
Dave H.
Thank you Dave. A few years back I posted this same question and got several hits in stating the pin was to be in line with the bridge. I stand corrcted and it is not the first time..nor perhaps the last time LOL..I built the above bridge to be removable, so now to correct five bridges, However i hate to say, those shoes sure look better to the eye wrong, then correct LOL
Anyhow thanks again Dave, also for explaining rotation....John
Don Z wrote: jwar wrote: I kind of like them as they set off the end of the bridge by giving it a bit of clearence. However the average visitor may not notice if absent. .This would be close to what you have, being I used plate gurder parts for this bridge.It would be easy to scrach build if your into working with small parts, John,I have a question regarding the bridge shoes in your photo. Is your bridge shoe installed so any movement would be perpendicular to the rails? I'm about to build a girder bridge, and I thought the shoes would be installed in line with the beams. I'd appreciate your input so I build this bridge correctly.Thanks,Don Z.
jwar wrote: I kind of like them as they set off the end of the bridge by giving it a bit of clearence. However the average visitor may not notice if absent. .This would be close to what you have, being I used plate gurder parts for this bridge.It would be easy to scrach build if your into working with small parts,
I kind of like them as they set off the end of the bridge by giving it a bit of clearence. However the average visitor may not notice if absent.
.This would be close to what you have, being I used plate gurder parts for this bridge.
It would be easy to scrach build if your into working with small parts,
John,
I have a question regarding the bridge shoes in your photo. Is your bridge shoe installed so any movement would be perpendicular to the rails? I'm about to build a girder bridge, and I thought the shoes would be installed in line with the beams. I'd appreciate your input so I build this bridge correctly.
Thanks,
Don Z.
I was wondering about that too. I thought they went the other way.
Dave H. Painted side goes up. My website : wnbranch.com
- Luke
Modeling the Southern Pacific in the 1960's-1980's
Don Z,,,dehusman is on target with your question, now I need to ask him a question..
Mr. dehusman. I understand one end fixed, the other left to expand/contract. Dont get me wrong here, Im not saying your wrong..but why do they (Prototype), would want the end of the bridge to rotate. Hope ya anser me, its now one of those thinking things, that will bug me all day LOL...John
Typically there are two types pf bridge shoes under a bridge. One is a hinge that rigidly attaches the end of the bridge to the abutment, prohibiting that end of the bridge from moving vertically, horizontally or side to side, but allowingthat end of the bridge to rotate about the hinge. The other end of the bridge has a shoe that prohibits vertical and side to side movement, but allows that end to shift longitudinally and to rotate. That way the bridge is free to flex as a load moves across it and to expand or contract with temperature changes.
larak wrote: Lothar,I make them out of styrene. Good enough and looks a lot better then barefoot Karl
Lothar,
I make them out of styrene. Good enough and looks a lot better then barefoot
Karl
I agree, unless it is a bridge that's right in your face, even a simple block of rough shaped styrene is enough to simulate the shoe. The most important aspect is the space under the girder on the shoe shelf of the abutment.
Even at this distance, the detail of the ME shoes are hardly noticable
Modeling B&O- Chessie Bob K. www.ssmrc.org
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If its a large foreground bridge on a concrete or stone abutment I will try to put something there. I have used some cast brass ones, but haven't done one in a while. A way to scratch some would be to take a strip of roughly 12-16 scale inch wide styrene and cut pieces off at 45 degree angles, making little triangles. Round the 'top" point of one and laminate 5 together, alternating up and down triangles, making sure the rounded one is on the outside.Put a piece of styrene on the top and bottom of the triangleas and you have a bridge shoe.
Alternatively you could get some 1/8" Plastuct "I" beam and cut some pieces a long as the base of the girder is wide and then put 3 together to form a shoe (a different type of shoe from the one described above).
Small girders just have a plate on the abutment.