A market has emerged for hammers in the seven-tonne and upwards class, which generally require a host machine in the 65-80t class. This does not seem to be an obstacle for the contractors who have bought these machines, as the productivity of the larger option seems to far outweigh their additional cost.Atlas Copco, Sandvik (formerly Rammer) and Indeco have all sold machines of this size in Australia, and competition is certainly strong between those brands not just at the upper end but across the range.The bulk of these have been sold into Victoria, and Tino Vinella of Victorian Sandvik hammer dealer Walkers Hammers told Contractor he believed the first of these was a Rammer G130 sold to contractor Paul Doherty for use on a 65t Hitachi ZX650H excavator. At the time of purchase, Doherty was looking for something larger than the 3.15t Rammer G90 City hammer that he had mounted on a 30t Hitachi excavator. The G90 had proved a good, reliable hammer but a deep rock excavation project was testing its capabilities and in the worst conditions only a single 2.4m pipe was being laid in a day. By doubling the size of excavator and hammer, it was possible to increase production to six 2.4m pipe lengths per day. Melbourne has a wide range of ground conditions, but the northern and western suburbs contain some very hard rock that, in a non-urban environment, would probably be blasted.Vinella says the larger excavators are still relatively easy to transport, but the productivity gains of larger hammers have made a big impact over the past two years.Atlas Copco offers the HB 7000 in the 7t breaker class and has several units working in Australia. It is also due to introduce a new breaker, the HB 3600, to fill a gap between the HB 3000 and HB 4200 in its heavy breaker line-up (the model designation roughly equates to the operating weight in kilograms).Waiting in the wings is the model HB 10000, which at 10t is claimed to be the largest production breaker in the world (Indeco is believed to have an even larger prototype operating in the United States).Features of the Atlas Copco heavy breaker (HB) range include the optional DustProtector II system for preventing dust and foreign bodies from entering the lower breaker section; the ContiLube II automatic lubrication unit that uses replaceable cartridges and delivers chisel paste only as required; the VibroSilenced damping system; the AutoControl automatic stroke-switching system that maximises percussive performance, reduces energy on blank strokes and starts the breaker in short-stroke mode to facilitate centring; and PowerAdapt, which avoids excessive pressure when the hammer is shifted between different excavators that may have different hydraulic settings.The HB 10000 has a single-blow energy of more than 16,000 joule (25% higher than the HB 7000), and in some applications has doubled the production of the HB 7000. The increased availability of large excavators around the world has made it possible to release a hammer of this size, but Atlas Copco will only bring it to Australia in circumstances where it can back the hammer up adequately and owners agree to maintain the hammer under an Atlas Copco ProCare service package.This seems to be a universal concern of the major brands – that a new model is not introduced to Australia until parts and training are in place to support it, and that adequate ongoing maintenance is performed on large hammers in particular, because of the dollars tied up in the investment.Where the required maintenance includes regular return of a breaker to the workshop, then this would seem to preclude these hammers from working on remote pipeline projects and the like unless an exchange unit was available – something that is difficult to achieve in a unit where the total market is very small and the investment can be in six figures.Indeco is the most recent entrant in the large hammer market, with three HP12000 rock breakers now operating in the Melbourne region. Two of these are with Azzona Drainage and the other is with Armstrong Constructions, and all are working on deep rock trenching in the west of Melbourne. The HP12000 weighs 7.8t, stands 4m high, has a 215mm chisel, and has a power rating of 18,900 joules and a strike rate up to 550 blows per minute.The machines have impressed with their reliability and performance in the time that they have been operating, and Indeco says it hopes to sell more of these hammers in Australia in the future.
