Above the railhead guides?

[Boyd]

Have there ever been any switches, crossovers or ?? that used an above the railhead guide for the wheels?

[gardendance]

I'm not sure what 'above the railhead guide' means, and once rail transport used flanged wheels I'm not sure why it needs anything other than the rail to guide the wheels.

Are you perhaps talking about something like SEPTA's route 11 trolley's grade crossing with CSX on Main St in Darby PA? It has no frogs, the railroad track's continuous, the trolley track's interrupted. Since the crossing's something like a 45 degree angle only one wheel on each axle rides up and over the railroad track at a time, the other wheel's still on the other track, and its flange should take care of guiding the trolley.

[Overmod]

Boyd

Have there ever been any switches, crossovers or ?? that used an above the railhead guide for the wheels?

I think he means things like portable turnouts.  Again I feel the lack of a good Forum search feature; we had a thread on this topic no more than a couple of months ago, and perhaps someone here remembers where to find it.  These are all temporary things -- not built into the track.

If I remember correctly, there were a couple of designs of 'frogless' switch that involved above-railhead-level elements.  None to my knowledge were successful... or particularly safe... once car weights and train speeds began to increase in the 19th Century.

[mudchicken]

Flange Bearing Frogs? (Like with crossing frogs/diamonds, low speed Flange bearing frogs are in limited use) - OP's original statement is confusing, at minimum.

[gopherstate]

Perhaps he's refering to self guided frogs.  They have what could be described as "above the railhead guides".  I believe they are mostly used in yards and industrial tracks.

[CShaveRR]

gopherstate

Perhaps he's refering to self guided frogs.  They have what could be described as "above the railhead guides".  I believe they are mostly used in yards and industrial tracks.

This is what I thought of immediately here.  There are (or were) plenty of these frogs around Proviso.  When they're used, the guard rail along the rail opposite the frog is not necessary.  They obviously wouldn't be any good where plows might be damaged or cause damage (and obviously not in street trackwork!).

[BOB WITHORN]

In Durand, Mi. the CN E / W dbl. track main is continuous welded rail. The Great Lakes crosses N /S. There equipment rides up and over the CN on guides so CN can maintain speed through town.

[cx500]

As well as self guarded frogs, sometimes you may also find a switchpoint protector that similarly protrudes above the rail head on the field side.  In general neither will be used on a main line where train speeds are higher.  And of course the flange-bearing frogs already mentioned that have recently come into limited use for little used routes.

The only place I personally have seen a portable turnout that sat on top of a track was in what was close to a mining railroad, namely the narrow gauge railway that hauled out the muck during construction of CPR's Mount MacDonald Tunnel.  That type of equipment is designed to handle pretty rough track, so it could handle the significant hump.  The crossover between the two tracks would be dragged up from time to time as the heading advanced.  I think street railways may occasionally have used something similar in the past as a temporary measure during reconstruction projects.

John

[Anonymous]

An important note on self-guarding frogs (at least where I work) is that hi-rail vehicles cannot pass over them. This isn't a problem in yards but for this reason they're generally inadvisable on the main line.

[Paul_D_North_Jr]

Photos of self-guarded frog: http://upload.wikimedia.org/wikipedia/en/2/2e/Cast_frog.jpg 

http://www.rmweb.co.uk/community/uploads/monthly_12_2012/post-9016-0-35595100-1355744272_thumb.jpg 

Links to info on switch point guards or guard rails:

http://www.clevelandtrack.com/products-services/track-work-components/adjustable-switch-point-guard/ 

http://www.wch.com/pdf/catalog/swtchpntgrd.pdf 

http://www.voestalpine.com/nortrak/en/products/Special-Trackwork/Switch-Point-Guards/

- Paul North. 

[Boyd]

The last post answered my question. The guide that guides the outer side of the wheel I thought was interesting.

[Paul_D_North_Jr]

gardendance

[snipped - PDN] . . . Are you perhaps talking about something like SEPTA's route 11 trolley's grade crossing with CSX on Main St in Darby PA? It has no frogs, the railroad track's continuous, the trolley track's interrupted. Since the crossing's something like a 45 degree angle only one wheel on each axle rides up and over the railroad track at a time, the other wheel's still on the other track, and its flange should take care of guiding the trolley.

See the photos (not mine) of this at the links below:

http://www.rrpicturearchives.net/pictures%5C15204%5C07%2011-06%2022.JPG 

http://www.subchat.com/readflat.asp?Id=513242&p=1#513345 - "PHOTOS: B&O/SEPTA Route 11 Darby crossing" from Nov. 2007 - some interesting comments there, too.

- Paul North.