This article is devoted to the review, study and analysis of the existing types of circulation used in the design of hydraulic drives of construction machines. Three main types of circulation are distinguished: closed, open, and semi-closed. A comparison is given and the characteristic features of each of them are described. Particular attention is paid to semi-closed circulation because it is under investigated. The sequence of movements of the equipment elements during the work cycle is shown. The results are presented, in the form of a diagram of flow rates in the actuators of an excavator planner, made by semi-closed circulation. This work will be of interest to specialists in the field of designing volumetric hydraulic drives of construction vehicles.

The problems of operation of hydraulic actuators in hydraulic press are considered. Design errors of hydraulic cylinders are identified. As the result of the simulation in the AnsysCFX, a new design with better strength properties is obtained, and the operational life of the hydraulic cylinder is increased. Also the pictures of the stressed-deformed state before and after structural changes are obtained.

This article discusses a way to solve the problem of operational quality control of concrete in the construction of critical structures with the use of small-sized testing machines. To reduce the testing machines size, it is proposed to use a high-pressure hydraulic drive. As a promising way to control the machine, the practical experience is described of using a pump with a constant displacement, the drive of which uses an electronic frequency converter.

The problems of controlling the gates of hydraulic structures from the point of view of modernizing current systems and expanding their capabilities are considered. A variant of the modernization of a discrete directional control valve is presented, which ensures the further implementation of a digital system for controlling the speed and position of the hydraulic control regulating element of hydraulic structure.