Flange-bearing frog

Modern flange-bearing frogs for use in freight railroad applications are a relatively recent development as a means to reduce maintenance costs associated with turnouts and diamonds, where rails must cross one another.

Flange-bearing frogs have been used by street railways for more than 200 years as a means of reducing noise pollution in populated urban settings.

The patent describes the technology as, "designed to support a railroad wheel to roll through the frog on its flange rather than requiring its tread to jump across a flangeway gap."

[2] Conventional frogs require a gap of around 2 inches (51 mm) in the running surface of the rail to allow adequate clearance for the flange of a railroad wheel.

[4] Because the flange rides on a continuous surface in a fully flange-bearing mode, the impact loads generated by the flangeway gap of conventional frogs are eliminated.

[1] As previously mentioned, flange-bearing frogs are quieter than conventional frogs—again, because of the reduced impact loads—which provides a potential benefit when implemented near residential areas.

[4]) Combination tread- and flange-bearing frogs are used in turnouts and are designed to account for various stages of wheel wear (in which the tread of the wheel will wear thin, effectively increasing the flange height): It is worth noting that as the tread-bearing loading environments begin to manifest themselves, the same impact loads which cause trouble with conventional frogs will return.

[5] In 2006, CSX installed a full flange-bearing diamond at Shelby, Ohio, the first application of this technology on a North American freight railroad.

The Transportation Technology Center in Pueblo, Colorado, has installed an OWLS diamond on their property, where they perform research for various railroad entities.