Currently, great emphasis on reducing energy consumption and harmful emissions of internal combustion engines is placed. Current control technology allows us to customize the operating mode according to the currently required output parameters, while the tuning of mechanical systems in terms of torsional vibration is often ignored. This article deals with a semi-active torsional vibroisolation system using pneumatic flexible shaft coupling with constant twist angle control. This system is suitable, as it is specially designed, for the tuning of mechanical systems where the load torque has fan characteristics (fans, ship propellers, pumps). The main goal of this research is to verify the ability of an electronic control system developed by us to maintain the pre-set constant twist angle of the used pneumatic flexible shaft coupling during operation. The constant twist angle control function was tested on a laboratory torsional oscillating mechanical system. Presented results show that the proposed electronic control system meets the requirements for its function, namely that it can achieve, sufficiently accurately and quickly, the desired constant twist angle of the pneumatic flexible shaft coupling. It is possible to assume that the presented system will increase the technical level of the equipment where it will be applied.

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.

Firefighters are regularly exposed to risk of injuries as a result of their intervention activities connected with hazards from fire and explosion, as well as due to carrying heavy personal working equipment and injured victims from accidents. Another hazardous factor is working under unfavorable weather conditions and also moving on slippery or bumpy surfaces. Employers provide personal protective work equipment to employees if a hazard cannot be eliminated or reduced by technical means, such as means of collective protection or methods and forms of work organization. Personal Protective Equipment (PPE) should provide effective protection against existing and foreseeable hazards and should not in itself create a greater risk. It should be adapted to the existing and predictable working conditions and working environment at the work site, meet the criteria of ergonomics and the health condition of an employee as well as be suitable and adapted to the wearer’s body so that, if possible, there is no risk of harm to the employee’s health. The aim of this Special Issue is to explore the limits of sustainable implementation of additive technologies within current manufacturing practices and current requirements for personal protective equipment for firefighters. More precisely, the goal of this special article is to show new ideas in firefighting footwear such as a quick donning and doffing system as well as various other improvements and sustainable design of firefighting footwear. The aim is to present new ideas and concepts, the latest advances, and technical tools supporting the sustainable use of protective firefighting footwear. Special attention will be paid to standards that ensure the highest standard and quality.

Today, being a member of the Fire-Rescue Department (FRD) is challenging as it is a risky and professionally demanding job, which often requires an individual schedule both in terms of physical condition and psychological knowledge as well as safety and health protection at work. Apart from the standard services provided by the FRD and the integrated rescue system, their members also participated in hundreds of interventions during emergencies and crisis situations to mitigate the impacts of the pandemic on society.

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.