Re: Tracks to the CRF

John,
Your standard frogs (rail bound manganese insert, self-guarded manganese, rigid bolted and flat top) all have flangeways on each side of the top running surface of the frog and they are rigid with no moving parts.
The spring frog has a series of holes along the length of the casting in which bolts with springs on each end hold separate guard rails in compression against the interior frog casting. These guard rails have tapered wings on each end so that as a wheelset approaches the frog, the wheel flange forces the springs to give thereby opening up a flangeway for the wheel flange as it passes through. As the wheelset exits the frog, the springs squeeze the guard rail back tight against the interior frog casting.
While all of this is going on at the frog, a standard guard rail on the opposite running rail is helping to pull the wheel flanges away from the frog point in a facing move. This prevents the wheel flange from picking the point or climbing the frog and causing a derailment.
Hope everyone can understand all of that.