Yes,,,real railroads use spring switches. In fact the Seashore Trolley Museum here in Maine have them on the main line so they can run without having to stop and throw switches with oared passenger cars.Geochurchi wrote: ↑Thu Mar 17, 2022 7:12 amIt seems to me that the real reason for the springs is to prevent a derailment if a train is going into a turnout in the wrong direction , do real railroads have these devices?Bill Shields wrote: ↑Wed Mar 16, 2022 8:14 am less parts all seems like a good idea until someone runs through the closed switch and derails and entire train full of cars and or damages the switch because something is now bent
the, all of a sudden -> that $4 spring seems like a good idea.
Why are these springs necessary
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Re: Why are these springs necessary
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Re: Why are these springs necessary
So what should the spring rate be, please? Would McMaster Carr part #1986K609 be an acceptable spring for 7-1/2" gauge?Pontiacguy1 wrote: ↑Tue Mar 15, 2022 3:04 pm When you build a switch with the springs in it to move the points, I.E. a Sprung switch, you need to be careful about how stiff you make your springs. if they are too stiff, then lighter cars will end up derailing instead of moving the points over and running through the switch. If they are too light, then the switch will tend to not move all the way over into the proper position when you throw it, especially if it has a lack of lubrication or a little bit of dirt or tree sap or whatever in it that might make it want to stick.
Thank you,
Jeff Smith
Florida
Re: Why are these springs necessary
"...with oared passenger cars."
Makes me picture a Roman Galley...
RussN
Makes me picture a Roman Galley...
RussN
- PeterCraymer
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Re: Why are these springs necessary
Strasburg has spring switches in multiple locations along the line and see many operations everyday.
Re: Why are these springs necessary
Oared passenger cars are for those really steep grades.
7.5" Allen Mogul
3 x 7.5" West Valley Baldwin Westinghouse Electrics
The railroad is almost done.
G. Augustus
Monte Rio, Ca.
3 x 7.5" West Valley Baldwin Westinghouse Electrics
The railroad is almost done.
G. Augustus
Monte Rio, Ca.
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Re: Why are these springs necessary
Spring rates are a function of the switch mechanism and minimum weight on an axle.
Irrespective of what anyone suggests, you are going to have to $ few springs, install the appropriate mechanism on a turnout, find the LIGHTEST car at the track....and play with it.
After you have done a few, you will have a pretty good idea of what is needed.
As a starter, you can push a lightweight car into an existing switch while you pull with a spring scale until the wheel rides up and over instead of through....and still puts the points back in place after the car has passed.
Rough...but a starting point.
A small 'bobber' caboose would be a place to look at for lightest wheel load.
It is not rocket science, and the effort to learn very rewarding.
Irrespective of what anyone suggests, you are going to have to $ few springs, install the appropriate mechanism on a turnout, find the LIGHTEST car at the track....and play with it.
After you have done a few, you will have a pretty good idea of what is needed.
As a starter, you can push a lightweight car into an existing switch while you pull with a spring scale until the wheel rides up and over instead of through....and still puts the points back in place after the car has passed.
Rough...but a starting point.
A small 'bobber' caboose would be a place to look at for lightest wheel load.
It is not rocket science, and the effort to learn very rewarding.
Too many things going on to bother listing them.
Re: Why are these springs necessary
Jeff...
There's no good way to determine the spring rate in advance. It's something you "get a feeling for" by moving the points during turnout assembly. When setting the spring stops/collars...push the point over maybe 6 to 8" back from the tip of the points. You're trying to simulate a wheel trailing thru the switch and pushing the points to the side as the train passes. Springs need to be set so train wheels can easily push the points out of the way, but still spring back and nest against the stock rail.
Will add...I don't recommend "oiling" the ties so the switch points can move. Oil only attracts ballast, grit, grim, dust and other to gum up the works. Instead, if you haven't done so already, consider putting stainless steel slide plates under the switch points. Can even cut up stainless steel banding for this. After installation, let Mother Nature clean the shims when it rains!
Spring adjustments were done to the side for easy access by moving a spring stop collar. Use of ferrous materials was minimized to maintain smooth operation of the points and switch throw mechanism. The white nylon block(s) were eventually replaced with black nylon to avoid UV degradation.
Can also bend the switches with a slight "crown" so when unloaded, the point only contacts the ties/shims near the point ends. When a train passes, there's usually enough weight there to push the point down so it contacts the slide shim. Make sense? Good luck. Carl B.
There's no good way to determine the spring rate in advance. It's something you "get a feeling for" by moving the points during turnout assembly. When setting the spring stops/collars...push the point over maybe 6 to 8" back from the tip of the points. You're trying to simulate a wheel trailing thru the switch and pushing the points to the side as the train passes. Springs need to be set so train wheels can easily push the points out of the way, but still spring back and nest against the stock rail.
Will add...I don't recommend "oiling" the ties so the switch points can move. Oil only attracts ballast, grit, grim, dust and other to gum up the works. Instead, if you haven't done so already, consider putting stainless steel slide plates under the switch points. Can even cut up stainless steel banding for this. After installation, let Mother Nature clean the shims when it rains!
Spring adjustments were done to the side for easy access by moving a spring stop collar. Use of ferrous materials was minimized to maintain smooth operation of the points and switch throw mechanism. The white nylon block(s) were eventually replaced with black nylon to avoid UV degradation.
Can also bend the switches with a slight "crown" so when unloaded, the point only contacts the ties/shims near the point ends. When a train passes, there's usually enough weight there to push the point down so it contacts the slide shim. Make sense? Good luck. Carl B.
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Re: Why are these springs necessary
The springs we use at the club are not very strong as you can easily move the points by hand.
Re: Why are these springs necessary
I think that there is a basic mistake about the spring forces needed in this solution:
Here in mid position, the resulting force on the switch blades is zero, and it rises only linear (from zero!!) when moving the nylon block, starting from contact position of the switch blades.
What you need instead is an ideally constant strong force when the switch blades get in contact.
This is given by the solution shown before:
This solution does not need a large travel of the spring actuator. Depending on the precision of the mechanics, it even can be near to zero after the switch blades get in contact. That is not affected by the travel of the switch blades when a train is cutting them.
Instead the first solution needs a travel of the switch drive that ensures that the spring force does not change too much even over the whole travel when a train is cutting the switch blades, and an aditional very large travel necessary starting from this spring force and continuing to zero spring force.
This requires much more mechanical work of the switch drive which is not practical in original size for economic and other reasons, and so this obviously is a big design fail, sorry.
Here in mid position, the resulting force on the switch blades is zero, and it rises only linear (from zero!!) when moving the nylon block, starting from contact position of the switch blades.
What you need instead is an ideally constant strong force when the switch blades get in contact.
This is given by the solution shown before:
This solution does not need a large travel of the spring actuator. Depending on the precision of the mechanics, it even can be near to zero after the switch blades get in contact. That is not affected by the travel of the switch blades when a train is cutting them.
Instead the first solution needs a travel of the switch drive that ensures that the spring force does not change too much even over the whole travel when a train is cutting the switch blades, and an aditional very large travel necessary starting from this spring force and continuing to zero spring force.
This requires much more mechanical work of the switch drive which is not practical in original size for economic and other reasons, and so this obviously is a big design fail, sorry.
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Re: Why are these springs necessary
Pray tell, what is that mistake? That turnout mechanism has been in use for decades with remarkable reliability. Other than the replacement of white nylon with the UV-resistant equivalent and enlarging the diameter of the throw handle, I can’t recall anything else being modified over the years. This is definitely an example of where over-engineering will result in more complexity, not better operation.
As Carl noted, and I will reiterate, no lubrication should be applied to any moving parts. As all sliding contact is between stainless steel surfaces, the natural cleaning action of rainfall is all that is needed. The only maintenance that may be required is that of picking debris out of the gaps between the points and the stock rails.
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