Switches and Crossovers

[Willy2]

How do switches and crossovers work? How do they work so that trains can go over them and not derail? What I'm really wondering is how the train wheels are able to go off the first track and go over the switch onto the other track.
Thanks for any information!

Willy

[mudchicken]

Willy:

To get you started......

Take a good look at a frog sometime. The frogs have flange ways cut in them in a figure "X"to allow the wheels to pass over and through them (the banging noise that you hear when a train takes the switch. At the beginning of the turnout, you have a "split switch" that holds gage and determines which way a train goes between the stockrails on the outside of the track. When you get comfortable with a two track switch, we'll introduce you to lap switches, puzzle switches, triple throw, equilateral and submarine switches to introduce a little brain damage...and then bring up stub switches that are rarely seen except on logging railroads....("mind candy" for mudchickens, we get to help do the steering out here!!!)

[Anonymous]

Best way to check it out is go to a hobby store that has a model RR and check out the way the switches work.

[tree68]

Just don't look at a prototypical puzzle track until you get the basics down. You might be able to pick out some of the stuff mentioned above in my signature picture.

[edblysard]

Willy, take a look at Trains mag, the may issue, in the Ask Trains section.
First question dealt with switch point protectors.
Note that the outside of the wheel can be used to pu***he wheel to one side or the other, by rubbing against the point protector.

Frogs have somewhat the same set up, not only do the wheel flanges guide it through the frog, the outside of the wheel is used to "steer" the wheel through, by means of a trough, where the outside of the wheel is guided by rubbing against the lip, if needed.


If you get the chance to SAFELY look at a frog close up, it will begin to make sense.
Kneel down, and look across the top of the frog, and you will see the outside of frog is taller than the rest of the track, it holds the wheel in line through the frog, along with the flangway in the middle of the frog.
Ed

[Anonymous]

mudchicken,
I'm comfortable with two track switches and others but what is a submarine switch?

[Willy2]

Okay: Before I hear an explanation on any other kind of switch, I think it would be a good idea if I took a close look at a frog (as Ed suggested). That way I can understand how at least a more normal switch works. Than I can be introduced to all the other kinds. Hopefully sometime soon I'll be able to see a frog and then I'll let you know when I'm ready for the stuff that will "introduce a bit of brain damage"!

Willy

[Anonymous]

Word of warning if you do decided to go and check a switch out on the railway, DO NOT STAND ON THE TIES. If the switch is an automatic being controlled by and RTC somewhere, and you have your foot in between the rails, say goodbye to your foot.

Those things can go at anytime, with no warning.

[mudchicken]

What the UniHead has described to you as just a frog is a "self guarded" frog with the raised edges. These are common in yard applications and you will not find these on any main tracks with a speed much greater than 15-20 MPH...It will not have a 9' to 24 ' long guardrail attached to the two stock rails (outside/ field side rails) opposite the frog. (The raised lip on a self guarded frog has the same purpose as a conventional guardrail, keeping the wheel passing over the frog from picking the frog point/ going down the wrong flangeway through the frog......the raised lip pushes against the outside sidewall of the wheel like a switch point guard and a conventional guardrail pushes against the backside of the wheel.......if either is scuffed up really bad, then there is something wrong with the gage through the frog area and it will need attention mui pronto...)

Toyoman- Submarine switches are found in streets and paved areas. The rigid switch stand (not a "flopover" operating folks*) is recessed, handle and all, in a rectangular steel box with a trap door lid. The split switch, switch points, are more often than not a cast tray with a big round heel and the points (two, but sometimes only one!) are only the equivilent to the top ball of rail and slide back and forth in the tray on the top of the casting. These castings and a whole submarine switch assembly, especially those using crane rail (rail with its own built in flangeway lip on one side), are ver-r-r-r-ry EXPEN$IVE to purchase and **[censored]** tough to maintain because of the abuse from street traffic, road grit, street maintenance people mistakes and accumulated garbage fouling the points. They have started showing up in light rail projects where switches are in the streets and designers cannot separate the turnouts from paved traffic areas....Kinda a " necessary evil" until a way is found to get the switch out from under all the asphalt in the street (should be subasphalt, not submarine). No matter how a roadmaster may try, after a rainstorm the handle in the box is under 4-6" of dirty water pooled under the trap door...The guy throwing the switch has to grope around in the dirty water trying to get a hold of the handle, raise it and push it over 180 degrees.

(*) Have seen switch crews back thru a submarine switch thinking it was variable/ flopover (No "V", no yellow paint) only to have chaos erupt when the trap door flies open, the handle springs up and in one case the handle struck the leaf springs in the locomotive lead truck with the spare knuckle& rerailing frog attached on a GP-9 switch engine...bending the switch handle...Had the switchman been standing closer, he might have been struck by the flying rerailing frog.[:-^][:-^][:-^]

[edblysard]

We have submarine switches all over the docks at the Porrt of Houston, real pain in the tail, not only do you have to stick your hand in really gross mud/water/oil/ god knows what to find the handle, most of the time it's so full of grit you almost cant throw it.
And, the crane rail switch he describes, at least the ones down here, have only one switch point, and its flush with the road surface, you have to creep up on them, so the switchman can see which way the switch is lined, there is no target, and the point dosn't move far, so you have to be almost on top of them to see.

willy, take macguys advice about TC switches, dont stand near them, for the obvious reason he pointed out.

I should have specified that you look at a yard frog, sorta a two for one, you get to see both methods of guiding wheels.
On a main line, at speed, a yard frog would most likley just get torn up.

And keep in mind, all this heavy stuff is basicly held on the rail by a 1" flange.

Ed

[Hugh Jampton]

Check out:
http://www.trainweb.org/railwaytechnical/index.html
Under Track there is a description and some pictures of frogs (called crossings round year)

[kenneo]

I'm sure MudChicken has seen the results of a selfguided frog run through at speeds greater than about 20. I'm talking about "mainline" operation. First, a wheel will strike the self-guide lip and then it (the wheel) will shatter if the speed is great enough. End of train, end of track and end of switch. That is why self-guided frogs are used only for track speeds under 15-20 or so.

On the Willamette Valley branches in Oregon, the SP had a large amout of street running -- Albany, Corvallis, Independence, Forest Grove, Hillsboro just to name a few locations where the mains went down the street. Of course, these tracks had switches, so what the SP did was first, if room as available, layed a regular track switch, boxed in the moving parts with extra long headblocks and throw rod to the switch stand at the curb. If no room to mount the stand at the curb, a flopover (standard yard groundthrow, old style with 180 degree arc for the handle) boxed and protected as above was set in the street. But then, on the SP, we became very adept at accomplishing mirracles from nothing special. Sometimes nothing at all.