A Lowering of Performance due to Leakage Flow Rate of Piston Rear-Chamber in an Oil Hydraulic Breaker

In order to verify the results of sensitivity analysis based on the analytical model introduced by the authors, an experiment have been carried out by using two different types of the oil hydraulic breakers. The experimental results obtained are summarized as follows. (1) In the case of the forward stroke of the piston, both pressure in the piston rear-chamber and the accumulator are maintained a higher value with decrease the leakage flow rate of the piston rear-chamber. (2) As the leakage flow rate of the piston rear-chamber decreases, the supply oil flow rate also decreases, but the blow velocity of the piston and the number of blow increase. As a consequence, the efficiency of the oil hydraulic breaker is improved sharply. (3) It is confirmed that the results of sensitivity analysis are supported by the experimental results. (4) It is necessary to design and manufacture an oil hydraulic breaker paying particularly close attention to the spaces between the sliding surfaces related to the piston rear-chamber.