Spring Switches are designed to stay in the desired position for ALL Facing Point movements. Spring Switches can be operated through in the Trailing Point direction - every time the trailing movement force the points into the trailing position, they will return to the facing point direction until the next wheel forces the points to the trailing position. If a train moving in the trailing point direction stops without having cleared the Spring Switch, and it then reverses movement without hand operating and securing the Spring Switch to facilitate that reverse movement - seriously bad things happen.
There are switches that can be lined by running through them (trailing point move) and they stay lined for the last route used. They are called “automatic” or “variable point” switches. We had one installed at Council Bluffs in the yard a few months ago. They, like spring switches, have signs or special switch targets to identify them.
At one time many switches in yards (those for the bowl or classification tracks) were like that. Mostly those type are gone replaced by those that can’t be run through. In some places, like in CB, they are making a limited come-back.
Jeff
There is a common meeting place near me that I think has spring switches at both ends, or did at one time. Seems like I saw a picture of one of the switches with a “SS” sign at some point in the past.
There are LP tanks at those points.
Access to them isn’t easy - maybe one of these days I’ll see what I can find. I think I can get to at least one of them legally.
“S” or “S S” on a switch target is a spring switch. The LP would be for a switch heater.
Jeff
I fully believe that the ‘run through’ switches have been replaced by non-run through switches simply so more Efficiency Test Failures could be chalked up every measuring period by the Weed Weasels.
Run-thru switches take maintenance. Can’t have that. Won’t you think of the stockholders? We’d rather have a crew run thru a switch, back up and make a huge mess that need Hulcher’s. Becuase…it’s…cheaper…?
If I remember from reading one of my hubby’s books Techachapi for years had spring switches for almost its entire length of it where it had the sidings on it unless it had CTC control. If trains where going to meet one switch was always set for the main the other end was for the siding.
Growing up in Cincinnati, I saw the streetcars use the Mt Adams incline. The double track street merged through a spring switch to a short stretch of single track which came to a trail and stay switch that led to the two approaches to the left and right inclined plane tracks with a similar arrangement at the other end of the inclined plane. So a down car would exit the plane and pass through the trail and stay switch to the single track leaving it lined for the next streetcar to head to the empty car. And the spring switch would put the down car on the outbound track. At the Fox River Trolley Museum, we use similar arrangements, Spring switchs on either end of a passing siding and trail and stay to return a car to the track it departed from if only operating one car at a time. If first car departs from the main, it trails throught the switch and when it returns it is directed to the main. When the next car leaves from track 2, it trails the switch and leaves it lined for track 2, so that when it returns, it goes to track 2. Of couse, on busy days when we run two cars and they pass on the siding, the returning car has to stop and thow the switch to get to the desired track.
It also takes maintenance turn and/or replace the broken switch lug of a non-runthrough switch in addition to Hulcher charges. Have to keep those E-test failures coming!
Yeah - I knew that. The question would be why (aside from preventing the switch from freezing). Is it remotely controlled, or a spring switch, or just so the crews don’t have to dig out the switch when it comes time to throw it?
A reconnaissance mission is in order…
If you try to spring it when it’s full of snow or ice bad things may happen. Something has to give.
Yeah - had a problem with a hand-throw once. Thought I could pull it through. You have no idea how hard the ice and snow will pack between the points and the stock rail… Especially when you discover there’s no switch broom on the loco…
CN used to put air wands on some locomotives to ease switch cleaning, they would be connected to the MR hose on one end. Then (predictably) someone got hurt somewhere, and they all got taken away.
We were never allowed to run through spring or semi-automatic switches when they are filled with snow/ice, but now we are not allowed to run through yard ones at all, this rule change coming about after a tank car ended up in two tracks at the same time (someone didn’t shove an entire car through it before pulling back, like you are supposed to, I think a yardmaster or supervisor was watching the point via camera when this happened).
There are very few main track spring switches left out here, but they will all be equipped with heaters and are allowed to be run through.
Spring switches are identified by a round white sign with “SS” on it, and semi-automatic switches have diamond shaped targets instead of round or square ones.
Additional, unrelated switch info, if the handle is painted yellow then there is a derail nearby. If the handle is painted white the switch has a point clamp/lock.
At least on one CTC installation, CPR (C stood for cheap) had a power switch at one end of each siding and a spring switch at the other. It saved a little bit of money, but meant that the dispatcher had no choice in which train took the hole at a meet. That was in the era when there were MoW personnel to keep the points clear of snow. That line is now mostly abandoned.
Both spring switches and semi-automatic switches (I have also heard them called rubber switches) do require more maintenance of the switch points. Where they still exist, the crews are now supposed to throw the switch manually before trailing through, but if somebody goofs at least the switch remains in good order.
John
Well, now I’m confusing myself. It almost looks like we’re saying the same thing- almost.
You’re saying that the wheels of a a southbound train in my example would force the switch points over, allowing the train to proceed through it (and into the siding)? How does that happen?
" In your case, the south switch would “snap back” after the southbound left the siding, but the north switch wouldn’t “snap back” until the northbound cleared it." < The first part makes sense. Can you further explain the second part?
[quote user=“Murphy Siding”]
blhanel
Murphy Siding
Any train going south ends up automatically being switched into the siding at Hills. The switch snaps back(?) after train goes through, lining the switch for northbound trains on the main. When the southbound train leaves the siding, that switch snaps back too, leaving the switch lined for the northbound trains as well.
I would guess that they don’t quite work that way, Murph. I would think the switch would stay in the preferred position until a train approaches it from the other track opposite of the switch points. The wheels of the train would force the switch points over, allowing the train to proceed through it. Anything coming from the point end would have to follow the alignment of the spring switch to whichever track it’s normally aligned for. In your case, the south switch would “snap back” after the southbound left the siding, but the north switch wouldn’t “snap back” until the northbound cleared it.
Well, now I’m confusing myself. It almost looks like we’re saying the same thing- almost.
You’re saying that the wheels of a a southbound train in my example would force the switch points over, allowing the train to proceed through it (and into the siding)? How does that happen?
" In your case, the south switch would “snap back” after the southbound left the siding, but the north switch would
I’m not sure I’ve ever seen or been unknowingly near a spring switch.
When a train “runs through” one, does it make a major racket, noise-wise? Seems like it would.
They creak a bit more, but it’s not too noticeable over the usual racket of moving railroad equipment.
Semi-automatic switches have a noticeable ‘snap’ when lined by a locomotive or car.
Murph - you have to have a idea of the difference between ‘Facing Point’ and ‘Trailing Point’. A Facing Point move will operate whichever way the points are lined
Lets say we are coming on Single track to the starting point of Double Track - the switch at the end of double track is a Facing Point switch for our movement. For the sake of argument the switch is lined to route our train to the right hand track which we will call #1 track. The End of Double Track Switch is a ‘Spring Switch’ in our example. We meet a train that is standing on the other track going in the opposite direction - when our train clears Single track and the Spring Switch - the signal system should be able to give a proceed signal to the train on the other track to TRAIL through the Spring Switch and then head out on Single Track; the points on the Spring Switch will remain lined for that route until the last car clears the switch at which time the points align for movement from Single track to #1 Track
That’s not at all what the spring switch points actually do, even if they are heavily dashpotted: they will constantly be trying to return ‘closed’ urged by the springs, and will probably substantially do so between the time each flange ‘passes’ and the next one starts forcing its way between the stock rail and the corresponding point.
A semi-automatic switch would stay open for the duration of the trailing move, but within the passage of the first car would have ‘snapped’ to the open position (even though the handle position wouldn’t reflect that) and of course will remain in that open position whether or not the trailing move is reversed. Don’t try a reverse even for a moment on a spring switch!