## 2 Materials and Methods  
In the study, the author's test rig was used, the task of which was to drive a wheelchair wheel with a friction-coupled test roller of the reversing lock module (Figure 2). The wheelchair wheel 1 was permanently connected to the shaft 2. The shaft 2 was connected via a torque gauge 3 to an electric motor 4. The torque gauge (Roman Pomianowski Electronics Studio, Poznan, Poland) used had a measuring range of 100 Nm, a sampling frequency of 100 Hz and a resolution of 0.001 Nm. It was responsible for measuring the driving torque M transferred to the wheelchair wheel and the rotational speed \(n\), which were used to calculate the power P delivered to the wheelchair wheel to induce rotary motion. All these values were measured at a common time base t. The test object in the form of the roller of the reversing lock module 5 was frictionally coupled to the wheelchair wheel 1 after using a linear guide system 6, stabilizing the roller of the reversing lock module 5 and a pressure screw 7 terminated with a pressure force sensor 8. A Zemic H3 pressure force sensor (Baumer, Frauenfeld, Switzerland), with a measurement range of 200 kg and an absolute measurement error of 0.02%, was used. The clamping force sensor was used to set the initial clamping force \(F_{d}\) before the start of the test and monitor its change as a function of time t during the rotation of wheelchair wheel 1 driven by electric motor 4. Knowing that the measured value of power P depends on the rotational speed n in order to maintain comparability of results for different variants of the rollers of the reversing interlock module and to reflect actual operating conditions, the speed of the wheelchair wheel n = 26 \(\pm\) 1 RPM was kept constant. This value of n, with the 24\({}^{\prime\prime}\) (0.6096 m) wheelchair wheel used, corresponded to moving the wheelchair at approximately 3 km/h. Figure 2: Schematic of the test stand used during the implementation of the study. Where 1—wheel of the wheelchair, 2—shaft, 3—torque meter, 4—electric motor, 5—roller of the reversing lock module under test, 6—linear guide system, 7—pressure screw, 8—pressure sensor. On the basis of the data obtained from the measuring station, the recording of the results from the force meter was analyzed first. From the raw data, the variation of the clamping force \(F_{d}\) during one revolution of the wheelchair wheel was isolated (Figure 3). This procedure made it possible to determine: the time required for one full revolution of the wheelchair wheel t\({}_{0}\) and the average clamping force, avg. \(F_{d}\). In further steps of analyzing the measurement signals, fragments were cut from the waveform of the power function \(P\) whose duration corresponded to the previously determined time \(t_{0}\) (Figure 4). This approach resulted in power waveforms as a function of time, where time varied within the range from 0 to \(t_{0}\). By integrating the function of power change \(P\) within these limits, the energy \(E\) needed to turn the wheel of a wheelchair frictionally coupled to the tested roller of the reversing interlock module (1) was determined. \[\int\limits_{0}^{t_{0}}P(t)dt=E \tag{1}\]  
The determined value of energy \(E\) is expressed in J (with substitution of power \(P\) in watts and time \(t\) in seconds) and is the main indicator used to evaluate the tested rollers and their impact on increasing the energy intensity of the wheelchair propulsion process. It is important to note that the determined energy value reflects the energy intensity of the entire system under study. This included the energy requirements for rotation of the bearing wheelchair drive wheel, elastic deformation between the wheelchair wheel tire and the roller of the reversing lock module, and rotation of the bearing roller of the reversing lock module.