The non-pneumatic tire (NPT) is a type of wheel whichdevelopment is related to the beginning of automotive development. The non-pneumatic tire (NPT) is a type of tire that does not contain compressed gases or fluid to provide directional control and traction. Nowadays, this type of wheel is more and more often used in special purpose vehicles, e.g., in military vehicles and working machines. The main feature of the non-pneumatic tire is a flexible support structure (including the part of the wheel between the tread and the rim). This paper presents the results of research aimed at determining the influence of the geometry of the NPT’s (intended for All-Terrain Vehicle - ATV / Utility Task Vehicle - UTV) load-bearing structure on its quasi-static directional characteristics. The experimental tests included the determination of the radial stiffness of research objects on a non-deformable flat surface and on a single obstacle, as well as the determination of the degree of deformation for the elastic structure and belt. The significant influence of the elastic structure’s shape and the elastomer, as the material forming the NPT, on its radial stiffness was revealed.

A vehicle’s longitudinal acceleration is one the parameters that characterize a vehicle’s motion dynamics and used, among others, to assess the comfort of public bus passengers. Rapid acceleration and braking performed by urban bus drivers can be deemed by passengers as uncomfortable and dangerous in some situations, especially for standing passengers. This paper presents an analysis of a public bus’s longitudinal acceleration recorded during extreme acceleration and braking attempts. The experimental tests were conducted on dry and wet asphalt and concrete surfaces. The test results allow for the statement that lateral acceleration depends largely on the road’s surface and its type. The maximum longitudinal acceleration values during rapid acceleration, depending on the surface, are within the narrow range of 2.18-2.81 m/s2. During braking, a public bus’s minimum longitudinal acceleration was within the range of -5.58÷-8.54 m/s2.

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The article presents the results of research on the assessment of vibrational comfort of children carried in child seats. The work analyzes the impact of the child's mass and the speed of the car passing through the speed bump on the level of vibration to which the passenger (child) transported in the child seat mounted on the rear seat of the car is exposed. The tested car seats were installed in a passenger car using the ISOfix base. During the tests, the measured values were the acceleration of the seat child seat, the backrest of the child seat, the rear seat of the car and the child seat ISOfix base. As part of the research, car drive through the speed bump were carried out at different car speeds and with different mass simulating the mass of a child. The test results were analyzed in order to determine the magnitude of vibrations generated during car drive through the speed bump. Based on the results obtained, the level of vibrational comfort of a child trip in a child seat was assessed.

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