What's a "frog?"

i heard on the scanner today that at mp 362 the bolts were comming out of the "frog" at the crossover. what part of the crossover is the "frog"?

Every switch or "turnout" has a frog. That's where the two running rails cross.

And by the way, the angle of that frog is what determines the "number" of the turnout. The "number" equals 1/2 the cotangent of 1/2 the frog angle (The "cotangent," if you remember your high school Trigonometry, is the reciprocal of the tangent, or the cosine divided by the sine)

thats what i thought it was but i wasnt sure. thanks otto.

Besides being an amphibian and a name for a turnout are there not rerail frogs?

STAR TREK 40TH ANNIVERSARY

Hi All,

So far so good. Anyone care to explain to him how the moveable frog on a high speed switch or turnout works ?

A movable frog moves. In concert with the points. In other words its not just the rails moving at the rail intersection but also the frog unit moving so that the angels are not so sharp.

It also makes for a smoother ride over the switch and reduces the chances of a derailment.

Hi All,

Correct, but you all have left out the main reason. Such a turnout or switch can handle speeds up to 125 mph.

U-Haul wrote:Besides being an amphibian and a name for a turnout are there not rerail frogs?

Yes there are re-railing frogs.

Oh, yeah, rerail frogs. See these things hangen' from the catwalk on the side of switch engines or piled near a switch shanty in a yard. The Dog House also had one or two at hand and the wreck train may have a couple dozen laying around.

The CN has been installing turnouts with movable frogs lately, they don't move with the points but are more like a spring switch. The flanges of the wheels open the frog. They're a lot smooter than traditional ones when you're going straight.

There are high speed turnouts with a "Moveable Point Frog".

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Union Pacific Rules
MOVEABLE POINT FROGS

ITEM 11: MOVEABLE POINT FROGS
Location:

Moveable point frog locations are:

Listed on subdivision pages by timetable symbol (11), and
Identified by signs that are 24 inches wide by 18 inches high.
Signs:

Approaching trains can view white signs with black borders and black lettering reading "Moveable Point Frog". These signs are placed directly across the track from each switch machine.

Employees who are facing switch machines can view white signs with red borders and red and black lettering. These signs are placed directly across the track from each switch machine.

Hand Operation:

In addition, decals are attached to each switch machine. These signs and decals read "IMPORTANT: This turnout is equipped with a moveable point frog. When hand operation is required, the switch machine(s) which operates the switch points AND the switch machine(s) which operates the moveable point frog must BOTH be operated. RULES 9.13 AND 9.13.1 APPLY."

Locations having three switch machines in the same turnout have signs and decals that read:

IMPORTANT: This turnout is equipped with three switch machines. Two are located on the switch point and one located on the frog point. To operate the turnout, follow the hand throw sequence below.

1. Operate frog machine completely.

2. Operate front switch point machine until the hand throw lever handle is in the vertical position.

3. Operate rear switch point machine completely.

4. Operate front switch point machine completely.

Operate three switch machines before starting movement at turnout locations that have two switch machines at the switch point and one switch machine at the frog point. Operate two switch machines before starting movement at turnout locations that have one switch machine at the switch point and one switch machine at the frog point. At crossover locations, you must operate double the number of switch machines.

Inspect all switch points and all frog points as explained in Rules 9.13 and 9.13.1.

Updated: 4/05/2005
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Last i heard in hoghead school, what, 8-9 years ago, they were gonna start putting in all moveable point frogs at all the x-overs. Havent saw any around here yet. The reason i heard there so great is less wear and tear, no more hours spent building them back up with wields.

Tom Curtin wrote:And by the way, the angle of that frog is what determines the "number" of the turnout. The "number" equals 1/2 the cotangent of 1/2 the frog angle (The "cotangent," if you remember your high school Trigonometry, is the reciprocal of the tangent, or the cosine divided by the sine)

HAHAHAAAA WOW!!! that's all I gotta say for this! I stopped at basic Giomatry.


On another note: Maybe I miss under stood the person who was telling me this but I (till now) always though a "Frog" was the now (thingy majig) that is installed under each car or most cars in case of a minor derailment. Now that I know it's not a frog... what’s it called?

That does not sound familiar at all - can you describe it more?