What is "track brake"

Track brakes are a form of brakes unique to railborne vehicles. The braking force derives from the friction resulting from the application of wood or metal braking shoes directly to the tracks (as the name suggests). Early examples of track brakes used on the horse hauled mineral tramways that preceded the steam locomotive were described as sledge brakes, and are usually associated with lines that used gravity propulsion.

Early systems used manual force to apply the braking shoes; more recently system have used arrays of electromagnets to hold the shoes against the rail. In some applications, the shoes are applied by powerful springs, and held off by mechanical or electro-magnetic force.