Western Railroad Discussion > Moveable Point Frog

For those who may not have seen one of these. This is a passive device, by that I mean it is actuated by the passage of the wheel flange. Normal (home) position is for the main, which is to the left in these pix. Photo sequence one-two-three is moving away from the points. Is there such a thing as a power-actuated frog?
Taken at CP Las Posas, Moorpark, California.
From a blimp. No trespassing involved.
...Lorenzo

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Two

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Three

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What you are showing here is a spring frog. A moveable point frog has a switch machine to line it.
And I'm no even going to comment about your blimp statement.

cs16 Wrote:
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> What you are showing here is a spring frog. A
> moveable point frog has a switch machine to line
> it.

Interesting. What circumstances occasion the use of either type of frog? High speed crossover, for example?

<What circumstances occasion the use of either type of frog? High speed crossover, for example?>

Spring frogs are used in low volume / low speed operations, and are designed to reduce wear in locations where most movements is on one route. Moveable point frogs are used in high speed turnouts where frog angles are very shallow, and/or in high volume locations where a lot of tonnage may move through the frog in either direction (such as end of double track) to reduce wear and tear on the frog. When hand lining a turnout with a moveable point frog, crews need to be sure to line both the switch point and the frog or there will be hell to pay!

czephyr17 Wrote:
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> <What circumstances occasion the use of either
> type of frog? High speed crossover, for
> example?>
>
> Spring frogs are used in low volume / low speed
> operations, and are designed to reduce wear in
> locations where most movements is on one route.
> Moveable point frogs are used in high speed
> turnouts where frog angles are very shallow,
> and/or in high volume locations where a lot of
> tonnage may move through the frog in either
> direction (such as end of double track) to reduce
> wear and tear on the frog. When hand lining a
> turnout with a moveable point frog, crews need to
> be sure to line both the switch point and the frog
> or there will be hell to pay!


This is a high speed spring frog. Notice the spring, kinda looks like a shock absorber.

What about those type of frogs that use a shock to absorb the force of the flange pushing it over? On Caltrain we have 50mph turnouts, and the frogs have these type of shocks, dunno if I'm using the proper terminology though.

cs16 Wrote:
-------------------------------------------------------
> What you are showing here is a spring frog. A
> moveable point frog has a switch machine to line
> it.
> And I'm no even going to comment about your blimp
> statement.

cs16 Wrote:
-------------------------------------------------------
> czephyr17 Wrote:
> --------------------------------------------------
> -----
> > <What circumstances occasion the use of
> either
> > type of frog? High speed crossover, for
> > example?>
> >
> > Spring frogs are used in low volume / low
> speed
> > operations, and are designed to reduce wear
> in
> > locations where most movements is on one
> route.
> > Moveable point frogs are used in high speed
> > turnouts where frog angles are very shallow,
> > and/or in high volume locations where a lot
> of
> > tonnage may move through the frog in either
> > direction (such as end of double track) to
> reduce
> > wear and tear on the frog. When hand lining
> a
> > turnout with a moveable point frog, crews
> need to
> > be sure to line both the switch point and the
> frog
> > or there will be hell to pay!
>
>
> This is a high speed spring frog. Notice the
> spring, kinda looks like a shock absorber.
>


Thank you, gentlemen!

rcall31060

czephyr17 Wrote:
-------------------------------------------------------
> <What circumstances occasion the use of either
> type of frog? High speed crossover, for
> example?>
>
> Spring frogs are used in low volume / low speed
> operations, and are designed to reduce wear in
> locations where most movements is on one route.
> Moveable point frogs are used in high speed
> turnouts where frog angles are very shallow,
> and/or in high volume locations where a lot of
> tonnage may move through the frog in either
> direction (such as end of double track) to reduce
> wear and tear on the frog. When hand lining a
> turnout with a moveable point frog, crews need to
> be sure to line both the switch point and the frog
> or there will be hell to pay!


Moveable point frogs are used in the Powder River area, especially in their crossovers.

This is a moveable point frog at Elvas wye(sacramento, Ca.). Sorry, I didn't step out on the main to take the photo (I was accompanied by a RR employee anyway)...

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Near Cabazon, CA on the UP (SP) Sunset route there are some movable point frogs.

fjc Wrote:
-------------------------------------------------------
> What about those type of frogs that use a shock to
> absorb the force of the flange pushing it over?
> On Caltrain we have 50mph turnouts, and the frogs
> have these type of shocks, dunno if I'm using the
> proper terminology though.
>
> >
>

Those would be the same type of spring frog that we use on metrolink.
The 'shock' as a hydraulic cylinder which allows fluid to move at a rapid rate when compressed and releases it slowly back to its extended position.
In the Los Posas pics, the point does not move, only the wing rail, hence a spring frog.

rcall31060 Wrote:
>
> Interesting. What circumstances occasion the use
> of either type of frog? High speed crossover, for
> example?
>
>

They are being put in on high speed track basically for a smoother ride and less shock on the frog on the normal route.

>Spring frogs are used in low volume / low speed operations,

Not necessarily, the BNSF and UP use them on 79 MPH track, for the normal direction of course.

>and are designed to reduce wear in locations where most movements is on one route.

One rule of thumb I read years ago, was that not more than 25%-30% of the traffic would be going through the diverging direction, but I'm not sure how closely this is actually followed in practise.

Some transit properties had double spring frogs, both wing rails sprung, but this had more to do with tracking problems associated with the narrow tires and flanges of streetcars, LRVs, etc.

>What about those type of frogs that use a shock to absorb the force of the flange pushing it over?

That's not actually a "shock absorber" but a hydraulic buffer, similar to those in spring switches. The idea is that it keeps the wing rail mostly open while the wheels go through, closing only after the last one. This way, fange wear and pounding are greatly reduced on the wing rail.

There is a "real" moveable point frog in the new turnout at the south end of two main tracks at Mowry on the Coast line (isn't in the timetable yet), and it's unlike the ones at Elvas.

I believe the rebuilt crossovers in San Timeteo Canyon and at Beaumont have warning signs posted beside them reading "moveable point frog" (Probably elsewhere along this recently overhauled line as well.).

Mark

I got a little confused while reading this thread...so I thought I would chime in as well....

">Spring frogs are used in low volume / low speed operations,

Not necessarily, the BNSF and UP use them on 79 MPH track, for the normal direction of course.
"

Yes, spring frog switches are used on mainlines that see a lot of traffic....but the actual switch received very little use. For example, around here we see tons of coal traffic. These spring frogs were placed on the local grain elevator tracks where they received very few cars. The actual switch may be used a dozen times a year. This switches virtually eliminate the wear on the frog as the wheels never leave the rail.

Actual movable point frogs are used on tracks where both sides of the switch are frequently used at high speeds. When the points are thrown, so is the frog. Again, these reduce the wear on the frog as the wheels never leave the rail. As mentioned before, a good use for these is crossovers and the end of double main tracks.

When I was reading thru this thread, I kept getting the impression that the spring frogs were used on high traffic lines on both sides of the switch. When I worked MoW, we could never use these switches unless we were going absolutly minimal speed, as we would frequently derail. The MoW equipment was sometimes just not quite heavy enough to open the spring frog. I never saw any trains using these spring frogs at any speed either. Only on the main....

~Matthew

I was told that the Metrolink criteria for a spring rail frog was that it was used on the diverging or springing side no more than twice a day, like a minor industry. It reduces the batter from a typical frog.

Actually, THIS is a movable point frog. The point of the frog has a switch machine attached to it (out of picture on left) and it moves the point of the frog to correspond to the position of the switch points on the turnout. If you look closely at the other end of this crossover you'll see a switch machine on the right at the frog of the far switch.

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Update: Photo(s) deleted because there are thieves on Trainorders who download and then use other peoples' photos in books, or simply print and sell the prints, for their own enrichment!!! I don't mind downloading them for your personal enjoyment but I draw the line at selling them or publishing them and claiming they are yours. Sorry I have to do this but the actions of a few screw it up for all.



Edited 4 time(s). Last edit at 02/11/20 13:01 by Railbaron.

So how do you handline the spring frog switch to make a facing point movement on the diverging route?

I am familiar with the proceedures for a moving point powered switch with the second switch machine.