The model hydraulic components made of plastics. A concept of a hydraulic system with elements made of plastics has been discussed. Selected criteria for selection of materials to be used in hydraulics have been listed. The basic models of hydraulic components and the test stand built from these elements have been presented. The summary indicates possible areas of application of low-pressure hydraulic systems made of plastics.

Keywords: hydraulic pump, pressure relief valve, directional control valve, hydraulic cylinder, test stand

Measurement of the internal leakage in the control valves DN 50 and the drive selection. The article presents the tightness results of a control valve. The impact of tightening torque of valve steam on the leakage volume between the valve head and the valve seat has been discussed. Tightness of new valves and valves after durability tests have been compared. The research results and the review of parts helped to formulate recommendations for selection of the valve drive.

Keywords: tightness, hydraulic valve, durability testing

Modified two-stage pressure relief valve – mathematical model and experimental research. The article presents a modified design solution for two-stage pressure relief valve. The principle of operation has been discussed and the mathematical model has been formulated. The experimental research of static and dynamic characteristics has been conducted. The influence of the throttle coefficient and the flow rate on the operation of the modified valve was identified. Static characteristics of the typical valve and the modified valve have been compared.

Keywords: static characteristic of pressure relief valve, pressure feedback, start-up of hydraulic system

The use of thermal imaging methods for the identification of thermal hazards in metallurgical equipment. Typical activities of maintenance services for monitoring of wear degree of machine parts have been discussed. The thermal imaging methods were indicated as a tool for predictive maintenance activities. Thermal imaging camera has been used to perform diagnostic tests of selected metallurgical equipment and to present the results in the form of thermal images. The safety of obtaining measurement data and the speed of verification as advantages of the method have been highlighted. Its limitations have been pointed out.

Keywords: thermal imaging camera, thermal image, hydraulic system, hydraulic cylinder