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This article presents the results of a study of the process of internal fluid leakage in the design of a gear pump with a biaxial connection. It is known that the volumetric efficiency mainly depends on the leakage of the working fluid through the gaps formed by the tooth heads and the pump casing, as well as between the end surfaces of the gears and the side walls of the casing. In addition, additional leaks occur along the contact line of the teeth. To reduce radial leaks, the gap between the gears and the pump casing is minimized, and to reduce end-leakage, the side walls are automatically pressed against the end surfaces of the gears by liquid under operating pressure. The design of the pump shows that the main internal fluid leaks occur in the gap between the gears and the housing. Naturally, these leaks require excessive energy consumption and, thereby, reduce the efficiency of the pump. The natural way to combat this circumstance is to reduce the marked gaps to a minimum. This is possible using an additional element - a biaxial sleeve. The dependence of the spring force on the fluid flow rate and the guaranteed gap between the ring gear and the pump casing has been analytically established. They are characterized by a drop in force with an increase in clearance and a rise in flow rate. This is due to an increase in the dynamic force in the gaps, which must be compensated by the spring.

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The main cause of the disagreement between the actual and calculated output data of hydraulic percussion mining machines is the erroneous feed of manipulation signals by the control units. For the maximal fitting of the calculated and actual figures, the continuous method of control action using the third time derivative of the law of motion of the main function element is accepted, namely, the accuracy. The mathematical models of control using displacement, velocity and acceleration are developed. The service factors of mining machines are found. Based on the theory of control and the mathematical logic theory, the logical circuits of formation of manipulation signals in each phase of the working cycle are developed. The main elements are converters, integrators and accumulators ensuring decomposition of elements of the logical circuits and further generation of appropriate control action. It is found that the simplest way is to generate the control action for acceleration of the key function element. For the developed circuits, it is recommended to use general charts of the control action change, implementable for a certain design of hydraulic percussion cutting heads in certain operating conditions.