This article investigates the steady-state performance of a closed-circuit hydrostatic (HST) drive using a variable displacement pump and a variable displacement motor where the speed of the drive is varied by controlling pump or motor. The drive is operated over a wide range of load torque and speed in two modes of operation: the pump controlled mode and the motor controlled mode. The efficiencies of the pump, motor, and the prime mover driving the pump are taken into account to analyze the overall performance of the drive. In this respect, considering various flow and torque losses of the HST drive components, the equations representing efficiencies of the drive are identified by comparing with the experimental data. The simulation is carried out using MATLAB. The results of the study may be useful to identify the control parameters of the drive to operate it at a reasonable efficiency zone.

The work presented in this article investigates the experimental study of the effects of various operating parameters such as oil temperature, speed, sizes and the load torque on the steady-state performance of the fixed displacement bent axis motor. In this respect, five different capacities of the motor are considered. The effects of the operating conditions and the capacities of the motor on its flow and torque-losses are identified. With an increase in pressure and temperature, gaps in the hydrostatic machine vary, and it also affects the viscosity of the fluid. The outcome of them on the performance of the motor is characterized. From the test data, a mathematical model of the losses is established that consider the influence of oil temperature, motor speed, load torque, capacities of motor and the system pressure. The model has shown good agreement with the test data; the overall efficiency of the different capacities motor at three different operating temperatures is compared. Such a model may be adapted to evaluate the performance of motor over a range of operating conditions. The proposed model may be utilized by the technocrats for selecting the bent axis motor drive for a given application.

Hydraulic components play a significant role in the mining and construction equipment. It is responsible for smooth change in the output speed, torque, and power of the machine. The hydrostatic drive powered by a constant speed electric motor is widely used in the propel system of the mining equipment. Regulation of the displacements of the pump and the hydro-motor of the drive facilitates the control of the straight running and steering of the machines. In the present scenario, better efficiency and ease of control are the critical aspects to be considered in the design and selection of the hydraulic pump and motor used in underground mining operations. The bent axis hydro-motor is one such equipment that is an electro-hydraulic component that can work in an adverse working environment. The present study deals with the performance analysis of fixed displacement bent axis hydro-motor at different operating parameters such as different temperatures, sizes, viscosity at different loads, and drive speed. For analysis, the hydraulic drive consists of a variable displacement pump rotated by a constant speed electric motor and a fixed displacement hydro motor. The regulation of the pump displacement controls the speed of the drive. Manually controlled hydrostatic drive propels the said machine against variable load demands. The present work investigates the performances of the hydro-motor used in the mining and construction machine through detailed modeling and experimentations. The steady-state performances are analyzed in terms of slip, torque losses and efficiency of the hydro-motor. The study finds the design guideline to operate the hydrostatic drive using such motors in a reasonable efficiency zone. The model is validated for various operating conditions of the equipment by comparing the predicted results with the test results. The outcome of the present work will be expedient for the preliminary design and assortment of similar hydraulic component used in the mobile, mining equipment.