The industries of shipping, shipbuilding and port operations are among those in which mechanical drives with piston machines are widely used. The wide use of piston machines is the result of many years of experience and many years of development and modernization of piston machines. Usually, they operate as mechanical drives with constant operating speeds, with the exception of drives with combustion engines, which operate in a wider range of operating speeds. The limiting condition of innovation of mechanical drives with piston machines, resulting from the nature of the piston machine operation, is the torsional oscillation. The effort to decrease an energy demand of mechanical drives requires the application of non-traditional working modes, which can be considered as a deactivation of the cylinders of piston machine or an expansion of the working speed range. One of the possibilities of eliminating these limiting factors is an application of a pneumatic tuner in mechanical drives, which, in contrast to traditional solutions, has a wide range of torsional stiffness that can be smoothly changed. During experimental measurements in the resonance area, at the operating speed of 700 rpm after torsional stiffness change, a torsional vibration value of 15 Nm decreased to 5 Nm.

Linear rolling guides, used in production machines for the realisation of linear motion, demand in industrial practice early damage identification to prevent production outages and losses. Therefore, the article aims for early damage diagnostics that use the principle of a load-free diagnostic part integrated into the carriage of the linear rolling guide. This principle was employed for developing an innovative method of damage identification to a guiding profile or rolling elements. The proposed innovative method is based on analysing vibration acceleration measured on the diagnostic part in the context of carriage position. In addition, a unique connection of an acceleration sensor to the diagnostic part through a mechanical component with defined parameters of stiffness and mass was designed. The innovative method was verified by laboratory testing on a designed functional sample of the diagnostic system. The computed reliability of the proposed diagnostic method reached 98%.

Presently, mechanical system vibroisolation is becoming increasingly important. One of the new approaches is semi-active vibroisolation using elements capable of changing a selected mechanical property. These include, among others, pneumatic flexible shaft couplings capable of changing torsional stiffness during operation. The main goal of the article is to examine the potential advantages of a newly patented pneumatic coupling over a current type with the same pneumatic element arrangement. For comparison, parameters determinable from static load characteristics were selected. These parameters are maximum twist angle and torque, average torsional stiffness, and the percentage of torque transmitted by the bellows rubber shell. In all cases, the new coupling had better properties. Since the prototype of the new coupling has not yet been produced, its parameters were determined from its mathematical-physical model. The article contains a full procedure to obtain the static load characteristic of a new coupling type, beginning with the determination of air bellows force/height and volume/height characteristics, then optimum sizes of coupling with regards to the operating range of elements, the dependency of element height on the coupling’s twist angle, and finally the computation of the static load characteristic considering isothermal gas compression. The presented procedure can be applied to any pneumatic bellows where the force/height characteristics of different pressures are given.

Torsional vibrations represent a significant dynamic phenomenon in rotating mechanical systems and are often associated with increased dynamic loading, fatigue damage, noise generation, and reduced operational reliability. Conventional vibration mitigation techniques are generally effective only within a limited frequency range, which restricts their applicability in modern drivetrains operating under variable loading conditions. Consequently, increasing attention has been devoted to nonlinear vibration control concepts based on the principle of targeted energy transfer. This paper presents the development and experimental investigation of a novel TET system with variable torsional stiffness intended for torsional vibration mitigation in rotating mechanical systems. The proposed concept combines the vibration energy redistribution capability of a nonlinear absorber with adaptive stiffness tuning achieved through pneumatic elements. The torsional stiffness of the secondary subsystem can be continuously adjusted by regulating the pressure within air bellows, enabling adaptation of the system dynamics to varying operating conditions. A dedicated experimental test rig with kinematic excitation was developed to investigate the dynamic response of the coupled mechanical system and evaluate the influence of variable stiffness on the TET mechanism. The study focuses on the analysis of vibration energy redistribution, the identification of optimal operating conditions, and the assessment of the potential of variable-stiffness TET systems for wide range torsional vibration control in rotating machinery.

Pneumatic flexible elements are widely used in mechanical systems for vibration damping, noise reduction, and improvement of dynamic properties. During cyclic loading, periodic compression and expansion of the enclosed air cause pressure fluctuations, airflow between interconnected chambers, pressure losses, and the conversion of mechanical energy into heat. This thermal loading may influence the stiffness, damping properties, durability, and operational reliability of elastomeric pneumatic elements. This study investigates the influence of the number of connecting openings on the thermal behaviour of two pneumatically coupled flexible elements under dynamic loading. Experimental measurements were carried out using a specially designed test rig at different charging pressures and with different numbers of active connecting openings. Three temperatures were monitored: the air temperature inside the pneumatic element T_air, the inner surface temperature T_in, and the outer surface temperature T_out. The results showed that increasing the number of connecting openings reduced all monitored temperatures and led to a more uniform temperature distribution within the pneumatic system. The thermal response also depended on the charging pressure, with a gradual transition from air-dominated heating at lower pressures to inner-surface-dominated heating at higher pressures. A simplified theoretical model was used to identify the main physical quantities influencing temperature development, including pressure, volume variation, airflow resistance, heat transfer, and energy dissipation. In addition, the interpretation of the observed temperature reduction was supported by a simplified analytical assessment based on the orifice–flow relationship, which showed that increasing the total flow area reduces the pressure difference required for cyclic airflow and consequently decreases pressure-loss-related heat generation. The findings demonstrate that the number of connecting openings is an important design parameter for controlling the thermal response of pneumatic flexible elements.

Torsional vibrations represent a significant dynamic phenomenon in rotating mechanical systems and are often associated with increased dynamic loading, fatigue damage, noise generation, and reduced operational reliability. Conventional vibration mitigation techniques are generally effective only within a limited frequency range, which restricts their applicability in modern drivetrains operating under variable loading conditions. Consequently, increasing attention has been devoted to nonlinear vibration control concepts based on the principle of Targeted Energy Transfer. This paper presents the development and experimental investigation of a novel TET system with variable torsional stiffness intended for torsional vibration mitigation in rotating mechanical systems. The proposed concept combines the vibration energy redistribution capability of a nonlinear absorber with adaptive stiffness tuning achieved through pneumatic elements. The torsional stiffness of the secondary subsystem can be continuously adjusted by regulating the pressure within air bellows, enabling adaptation of the system dynamics to varying operating conditions. A dedicated experimental test rig with kinematic excitation was developed to investigate the dynamic response of the coupled mechanical system and to evaluate the influence of variable stiffness on the TET mechanism. The study focuses on the analysis of vibration energy redistribution, the identification of optimal operating conditions, and the assessment of the potential of variable-stiffness TET systems for wide range torsional vibration control in rotating machinery.