The percussive-type pneumatic rock drill is a major noise source in mining. A new drill is described in which substantially quieter operation has "been achieved. Design of a prototype was "based on a simplified analogue simulation. A comprehensive simulation was then developed incorporating air expansions and contractions, air flow losses, reverse air flow due to cushioning compression, piston to drill-steel impact and mechanical friction. The principles of the simulation are described. Operation was verified by comparison with experimental results from prototypes. Optimization of drilling rate by variation of mass, geometry and working cycle parameters in the simulation is described. Test results from an experimental programme based on simulation predictions are presented.
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