These forged and precision-machined rings control the delivery of power from the engine to the track of a tank – if the left-hand brake ring is engaged, the left-hand caterpillar-track stops and the tank turns to the left, visa-versa for the right. Machined to tight tolerances, the rings are meticulously checked for non-visible cracks:  though relatively small at about 40cm diameter, should they fail in service, the tank will only move in a circle – a disastrous scenario on a battlefield. Process control and in-built quality assurance are key differentiators in this market.