Metso Mining and Construction’s product portfolio is expanding with the addition of a new rock breaker series designed for primary stationary crushing stations. Rock breakers are commonly used in primary crushing stations to break oversized boulders that are fed into the crusher and to clear clogging in the cavity. Today, most of the primary stations use this combination to guarantee smooth, continuous performance and to minimize idling caused by build-ups and blockages (Fig.). Earlier, Metso did not have its own hammer and boom combination available for stationary primary crushing stations. Based on customer demand, Metso was asked to provide a solution to meet this need. The new Metso MH-series hammers and MB-series booms include five boom-hammer combinations for jaw crushers and one for primary gyratory crushers. The hammer weights range from 400 kg (880 lbs) to 2200 kg (4840 lbs) and the corresponding power ratings from 18 kW (25 hp) to 45 kW (60 hp).