Operating problems of electrospindles with aerostatic bearings. In the paper, the operation problems dealt with during expertise works on the faulty electrospindles with gas bearings are described. The main causes of the bearing systems malfunction were identified. The impact of the electric motor cooling system on thermal deformation of the aerostatic bearings elements was analyzed. Steps to eliminate malfunction of the electrospindles were defined and presented in the paper.

Keywords: electrospindles, aerostatic bearings, thermal deformation

Aventic pneumobile – idea of the competition, engineering design, challenges. The idea of the pneumatic vehicles competition organized by Aventics Rexroth Pneumatics has been presented. An analysis of the design of the pneumatic vehicles which participated in the 2015 edition of the competition was carried out. In the paper, the essential issues concerning the design problems while preparing a new project for the competition are discussed. Moreover, the areas where the designs of the pneumatic vehicles can be optimized have been defined.

Keywords: pneumatic vehicle, vehicle design, design optimization

Requirements for modern electrohydraulic control systems of water turbines. Basic requirements for hydraulic systems used in control systems and water turbines have been discussed. The more important works on modernization of the old and design of the new control systems for the turbines have been presented. It has been argued that the introduction of modern technologies and automation of hydro-technical structures increases safety, boosts power and efficiency of the hydraulic units and minimizes operating costs.

Keywords: control systems, automation of hydro-technical structures, water turbines

Indirect method to determine the speed of pressure wave propagation in hydraulic lines. The authors have shown that the commonly used formula for determining the speed of propagation of pressure waves is limited to the thin-wall tubes. An indirect method of determining the speed for the thick-wall tubes and hoses, consisting in experimental determination of the substitute modulus of volumetric elasticity has been proposed. The method has been verified on the bench.

Keywords: hydraulic hoses, hydraulic tubes, pressure wave, substitute modulus of volumetric elasticity

Analysis of the electro-hydraulic system efficiency. The paper contains results of the analysis of electro-hydraulic systems efficiency using the electric motors with a low value of inertia moment driven through the inverters. Selected results of the analysis for the throttling and the volumetric control for the steady and the unsteady state of the hydraulic motor speed have been presented.

Keywords: efficiency, throttling control, volumetric control, electric motor