Comparison of the steady-state performance of hydrostatic drives used in the rotary head of the drill machine

This article presents a comparative analysis of steady-state behavior of hydrostatic drives of a drill machine used in mining application. Usually, a closed-circuit hydrostatic drive rotates the cutter head (drill bit) of a drill machine through its rotary head. In this respect, performance investigation of two such alternative drives is carried out through modeling, simulation and experimentation. One of the drives comprises a variable displacement pump and two high speed low torque (HSLT) bent axis motors with a gear reducer, whereas another one consists of an identical pump and a low speed high torque (LSHT) radial piston motor. To simulate the hydrostatic drives, the bondgraph models are made, where various losses are considered as resistive elements. Considering the characteristics of the losses obtained experimentally, the predicted performances of the systems obtained through simulation are validated with the test data. The dependencies of the losses on the pump displacement and the load torque on the drives are also analyzed. The characteristics of the drives with respect to the operating speed range of the drill machine used in mining operation are studied at different torque levels. On the basis of the results obtained, suitability of the hydrostatic drives for the rotary head of the drill machine is also discussed for different rock characteristics.