The Rail Switch Ballast Undercutter from HMA Materials Handling removes fouled ballast from underneath the railway track so that fresh clean draining ballast can be substituted. The machine is specifically designed to work on points, turnouts and crossings. The major materials handling elements are a horizontal excavating chain, a vertical cell type bucket wheel and three troughed belt conveyors.

The excavating chain removes all of the ballast to a depth of 300 mm below the underside of the sleepers. The bucket wheel digs a trench beside the railway track, allowing the excavator chain to rake ballast back into the trench. The bucket wheel also elevates ballast onto the conveyor system. The conveyor system comprises of a cross conveyor, main transfer conveyor and 6m long slewing discharge conveyor for dumping spoil into railway wagons or road vehicles.

The Rail Switch Ballast Undercutter from HMA Materials Handling is provided with a centre jack for lifting the machine some 300 mm above the rails. From this position, the machine can be rotated end for end and placed back on the rails, or it can be placed on special off-tracking rails for sideways travel to a parking bay beside the railway track. A set of motorised off-track wheels are provided for this purpose.