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Pere Marquette "Spring Switches"

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Pere Marquette "Spring Switches"
Posted by doughickman on Tuesday, April 6, 2021 7:37 PM

While reading about the Pere Marquette Railroad (before they took over the Chessapeak and Ohio Railroad in 1947) there is often a reference to "Spring Switches at the entrance and exit of yard(s)".  Were these switches with spring-loaded points held in the "closed" or "Normal" position?  Would they spring open (to allow railroad wheels to push the points into the "open" position?  Wouldn't that have made a great deal of noise?  Could it be modeled using an Atlas switch using the plastic manual control - or would some other spring be better?

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Posted by CGW103 on Tuesday, April 6, 2021 8:31 PM

The CGW had one at Ingalton Illinois, among other places. It was in the normal or straight position, but allowed trains on the divirging to return to the main with relative ease, however at restricted speed.

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Posted by ATLANTIC CENTRAL on Tuesday, April 6, 2021 8:40 PM

doughickman

While reading about the Pere Marquette Railroad (before they took over the Chessapeak and Ohio Railroad in 1947) there is often a reference to "Spring Switches at the entrance and exit of yard(s)".  Were these switches with spring-loaded points held in the "closed" or "Normal" position?  Would they spring open (to allow railroad wheels to push the points into the "open" position?  Wouldn't that have made a great deal of noise?  Could it be modeled using an Atlas switch using the plastic manual control - or would some other spring be better?

 

The Pere Marquette did not take over the C&O, the Van Sweringen Brothers bought the PM, then sold it to the C&O, who then merged the two companies in 1947 - then it was just the C&O. 

And in 1965 the C&O took control of the B&O.

Spring switches were moderately common.

There is one place were several are still in daily use - the Strasburg Railroad. 

Yes, they make a little noise, close with a bang after each truck passes thru.

Sheldon

    

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Posted by dehusman on Tuesday, April 6, 2021 10:28 PM

They are (or were) actually pretty common on most railroads.  They don't make that much noise, not that much more than the train itself.

Dave H. Painted side goes up. My website : wnbranch.com

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Posted by gmpullman on Tuesday, April 6, 2021 11:39 PM

Anywhere a single-car dumper was in operation you might find a spring switch or two:

 PRR_dock-Sandusky by Edmund, on Flickr

This one is at the McMyler dumper at the PRR dock in Sandusky, Ohio.

I often watched locomotives being turned on a wye at the NYC engine terminal in Collinwood, Oh. All three switches of the wye were spring switches. The hostler, working alone, didn't have to leave the engine to negotiate the wye. A real time saver.

Spring switches commonly had a sign designating them as such. They were mentioned in employee timetables, too. For obvious reasons the train could not back through a S-S once part of the train has passed over it without manually throwing the switch. It was not good to have to stop over a spring switch as the slack could possibly run out and "split the switch" if you weren't careful.

 Spring_Switch by Edmund, on Flickr

Good Luck, Ed

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Posted by doctorwayne on Tuesday, April 6, 2021 11:46 PM

We had one in the steel mill where I worked, but it was mostly a safety device if a drag of ingots was too long, and were mis-spotted...derailed ingot buggies could make quite a mess.  If they hit that switch, it simply flipped over to allow the buggies to roll through.

Wayne

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Posted by Outsailing86 on Wednesday, April 7, 2021 9:55 AM

Railroad track engineers developed a device called a Mechanical Switchman, which had a spring box to hold the switch points open for a few minutes. 

in modern times, you will see spring switches on a double crossover at the end of a Light rail transit line, when the LRT goes to the other track to run into the city. 

with signal requirements and PTC, on the mainline a conventional switch machine is required

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Posted by Overmod on Wednesday, April 7, 2021 12:31 PM

If the OP is still wondering, the spring switch is normally 'closed' and lined in one direction.  The 'spring' action allows a TRAILING move to push the points over without damaging the locking mechanism.

A normal spring switch just lets the points close positively after the flange goes through -- as you might suspect, the springs are VERY strong, for safety, so will snap the point closed fairly smartly unless some sort of dashpot is provided.  Now, if you were going through this kind of switch, stopped in the middle, and reversed or rolled back for any reason, every wheel that's gone through will now back up on the other route... with usually comical effect.  The Mechanical Switchman holds the points open for some set time -- there is both an open 'hold time' and a slower soft close -- to resolve this sort of potential problem.

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Posted by wjstix on Wednesday, April 7, 2021 3:00 PM

In a spring switch, the flange of each wheel of the train moves the moving rail of the turnout over just enough to allow the train to pass, then it goes back the way it was. The spring has to be strong enough to keep the turnout set the right way, but not so strong the wheels can't move it. After the wheel has gone by, the sound of the spring moving the track back the inch or two to where it was at the start isn't that loud I don't believe.

In HO scale, Kato's electric and manual No.6 turnouts work as spring switches if you make the adjustment on the bottom to make them non-power routing.

Stix
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Posted by gmpullman on Wednesday, April 7, 2021 3:10 PM

Overmod
     —and reversed or rolled back for any reason, every wheel that's gone through will now back up on the other route... with usually comical effect.

 171203_2_altoona by lmyers83, on Flickr

Cheers, Ed

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Posted by ATLANTIC CENTRAL on Wednesday, April 7, 2021 4:08 PM

wjstix

In a spring switch, the flange of each wheel of the train moves the moving rail of the turnout over just enough to allow the train to pass, then it goes back the way it was. The spring has to be strong enough to keep the turnout set the right way, but not so strong the wheels can't move it. After the wheel has gone by, the sound of the spring moving the track back the inch or two to where it was at the start isn't that loud I don't believe.

In HO scale, Kato's electric and manual No.6 turnouts work as spring switches if you make the adjustment on the bottom to make them non-power routing.

 

Loud is relative. I have ridden the train at Strasburg about 100 times in the last 63 years and while it is not a loud sound in terms of SPL, it is a distinct noticeable sound between a bang and a thud, as each wheel clears the point rail.

And in those early 20th century wood cars, you feel it happed as well.

Sheldon

 

    

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Posted by PM Railfan on Wednesday, April 7, 2021 7:34 PM

doughickman

While reading about the Pere Marquette Railroad (before they took over the Chessapeak and Ohio Railroad in 1947) there is often a reference to "Spring Switches at the entrance and exit of yard(s)".  Were these switches with spring-loaded points held in the "closed" or "Normal" position?  Would they spring open (to allow railroad wheels to push the points into the "open" position?  Wouldn't that have made a great deal of noise?  Could it be modeled using an Atlas switch using the plastic manual control - or would some other spring be better?

 

Hello Doug -

Im sure it was a mistype, but it was the C&O that took over the PM.

Spring switchs on the PM can be found pretty much everywhere other railroads would have them too... wherever timesaving and functinal. Im not sure which PM yards would have them though i would imagine Detroit for one. They werent uncommon and are still in use today.

I do know the PM used them on sidings, and in the back country where again, it would save time and expense to do so.

Usually spring switchs are set for 'normal' position. However, this would still be specific to location and use. Its not hard to to imagine a railroad having to use the 'Reverse' as the normal setting for a certain switch.

The noise level i suppose would be relavent to speed and weight hitting those points. Ive never seen a sprung switch traversed fast. And the sprung switchs i have seen were almost whisper quiet.

Yes, using an Atlas switch could be done. Matter of fact, if your cars are heavy enough, they will already role through the points. By accident, on occasion, i have run normal thru a reversed switch. The 'better grade' models went thru but usually lighter, lesser quality cars wont.

Either way, the rolling stock has to be heavy enough to push the points while remaining on track, the spring mechanism has to be pliant enough to give... but return.

However removing the Atlas mechanism and adding a spring would... make it true to its name.

 

-Douglas

 

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Posted by jeffhergert on Wednesday, April 7, 2021 7:36 PM

Outsailing86

 

with signal requirements and PTC, on the mainline a conventional switch machine is required

 

I know of a couple of places on signalled main tracks with PTC where there are spring switches. 

Jeff

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Posted by wjstix on Thursday, April 8, 2021 9:39 AM

I have a DM&IR employee timetable/rulebook from the 1980's, in one part it talks about spring switches. I believe (don't have it in front of me) the Missabe had 7 of them. They note that spring switches were indicated by the interlocking signals using lunar (white). 

Stix
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Posted by jjdamnit on Friday, April 9, 2021 3:18 PM

Hello All,

On the 2-foot Cripple Creek & Victor Narrow Gauge Railroad, all six of the turnouts are spring (sprung) switches (turnouts).

The track configuration is basically two wyes back-to-back.

As the wheel flanges approach the turnout they move the sprung turnouts to the opposite position.

If the sprung turnout is set to the diverging route the wheel flanges push the points aside to align with the normal position. 

When the sprung turnout is set to the normal position the wheel flanges push the points to the diverging route.

As each wheel passes through this arrangement there is an audible "clunk" as the points return to their set position against the rails.

When we passed through the first turnout this noise piqued my interest and I observed how the next turnout operated.

I also observed that there was no one "bending the rails" or operating the turnouts.

The spring that holds the points is about 2-feet long and 3-inches in diameter with the throw bar passing through the center.

Looking over the side of the car I could see the spring compress as each wheel flange passed through.

As the train passed back through these turnouts, in the opposite direction, the points were aligned for the opposing route.

This is basically a one-way-only arrangement.

If half of the cars passed through a sprung turnout and the train tried to back through the turnout it would result in the cars passed the turnout going in the opposite direction of the turnouts sprung position.

On all the sprung turnouts I observed there was a "manual override" if the train or car needed to reverse direction on the same track a brakeman could operate the turnouts by hand.

I could see how these sprung turnouts could be modeled with light springs that hold the points in one direction.

When the wheel flanges pass through the "held" points the spring would need to be stiff enough to return the points in the sprung position while not causing a derailment from the flanges riding up on the held points.

Hope this helps.

"Uhh...I didn’t know it was 'impossible' I just made it work...sorry"

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