The article presents the standard method of the evaluation of car drivers’ psychomotor reaction times. A characteristic feature of this method is the ability to conduct tests using real vehicles equipped with mobile measuring apparatus. Measurements are carried out on people whose task is to initiate specific maneuvers (such as: a braking or turning maneuver, a combined braking and turning maneuver, as well as e.g., the use of an audio signal) in response to external stimuli coming from different directions. The sources of the stimuli are light signals emitted by variable message signs placed around the vehicle. The developed control and measurement equipment allows us to realize various and complex test scenarios. It generates stimulus sequences, assesses the correctness of the driver’s response and measures its time. This method allows us to obtain sets of results from tests carried out under different conditions and variable test durations. The possibility of testing a large number of participants in a relatively short time and in repetitive conditions allows for reliable statistical inference. The paper presents examples of research results obtained on the basis of few thousand tests carried out on a large group of respondents. The registered data was statistically processed and referred to the literature. A high degree of correlation between the analyzed results and the literature reports proves that the presented method may be a source of data for the analysis of phenomena related to the time of the driver’s response, especially the influence of various factors affecting its values.

The paper presents examination of the properties of single-acting hydraulic drive for valves of internal combustion (IC) piston engines. In the valve actuation system proposed, a Caterpillar solenoid valve of the HEUI fuel system and a commercial hydraulic actuator were used as the distributor and final control element, respectively. The examination was carried out on a specially prepared model of the valve actuation system under consideration. The influence of various construction parameters of the system on the course of the valve displacement process was examined, with analysing such characteristic parameters of the process as delay in the start of the valve motion measured from the beginning of the current control signal, valve opening and closing times, time of the valve kept open, valve displacement vs. time curve, filling ratio of the area under the valve lift curve, and velocity of the valve hitting its seat. The construction parameters whose impacts were analysed included oil supply pressure, total working space volume, power supply voltage, distributor solenoid force, cross-sections of the distributor supply and overflow gaps, total mass of moving distributor parts, engine valve mass, actuator piston diameter, and valve spring characteristic curve. The necessity of using high supply pressures and high control voltages has been proven. Guidelines for designing engine valve actuation systems of this type have been given. It has been shown that due to low flow capacity, the distributors of the type used are only suitable for the hydraulic actuation of small valves of high-speed IC engines. Evidence has been produced that systems to advance the control signal in relation to the required valve opening instant must be applied to compensate for the valve actuation delay and the limited valve opening velocity. The fact that the valve displacement vs. time curve may be shaped within a relatively wide range has also been pointed out.

Paper discusses apparently opposing goal functions in terms of car’s comfort and handling. Short descriptions of passive, semi-active and active suspensions with their features are included. Thereafter, employing a two-mass quarter car model, an idea of damping control strategy in semi-active car suspension is presented. The results of performed simulation tests for various inputs are depicted and thoroughly discussed with comparison to classical passive suspension’s response. On the grounds of obtained results, conclusions are formulated. What is more, a layout of further work is outlined, with the aim of system’s response optimization in terms of comfort and handling features, as well as reliable validation of efficiency of proposed damping control strategy.

The aim of the article is to present and validate a methodology for collecting road load data on a vehicle, driving on roads and analysis of a drive data signal under the wheel in the time domain, using FRF (Frequency Response Function) and the MTS 320 eight-poster inertia reacted road simulator. The elaborated drive data, was used to control the actuators forcing the movements of the wheels and the coupling part of the semi-trailer during durability tests. The road tests were carried out by registering physical variables in the time domain, by a set of sensors mounted on a vehicle. The data was collected from roads categorized as motorways, national and local roads. Differences between the variability of the parameters, collected on the roads and the variability of the drive data under the wheel, were determined for the particular types of roads, for loaded and unloaded vehicle. The obtained accuracy of reconstruction of the road load data conditions was as high as 97%. Therefore, the proposed method is suitable for reliable durability tests with use of the road simulator.

This paper describes a research stand and results of experimental research of single-acting hydraulic drive for valves of internal combustion engines. The research stand of the hydraulic valve drive was consisted of: typical valve drive for high-speed internal combustion engine, commercial hydraulic actuator, commercial hydraulic accumulator and electrically controlled hydraulic distributor, which controlled the flow of oil supply to the hydraulic actuator. Rexroth commercial servovalve was used as hydraulic distributor for this valve drive. Components of hydraulic valve drive were mounted to specially designed research sleeve. On this sleeve complete drive, which consisted of a hydraulic cylinder and servovalve, was mounted. Drive control was performed in an open loop with a use of rectangular control signal. Displacement of the valve was measured by an optical displacement sensor. Tests were performed for constant lift of the valve, supply pressure set in the range of 6 to 10 MPa and at fixed temperature of the working medium and different initial deflections of valve spring. The behaviour of the drive was researched for bipolar and a rectangular control signals. Such range of measurements was to determine inter alia: the impact of the supply pressure and the control signals values on the drive work. Obtained results were used to verify the simulation model in a wide range of variation of the characteristic parameters of the electro-hydraulic actuator. The results of experimental measurements like valve movement and pressures in the drive were shown and analysed in this paper. With a reference to the valve movement, a detailed calculations of the valve kinematics were performed. Special attention was given to the opening and closing velocities of the valve, depending on the servo control signal. Subsidence valve velocity during its return movement was calculated. This subsidence valve velocity is an important parameter in terms of the applicability of this drive for the internal combustion engines. Valve opening time delay in opposition to the current control signal was also specified and discussed. Obtained results allowed to conclude that the proposed drive provides acceptable kinematic parameters for high-speed engines at supply pressures of at least 8 to 10 MPa. During the measurements acceptable valve subsidence speeds were obtained. It was found that there is a possibility of adjustment of this parameter by setting the slider servovalve negative overlap. Results became the basis of development of the model of this type of the drive. Further simulation studies will allow to evaluate the applicability of such valve drive for internal combustion engines. Further simulation studies allow to compare the proposed solution with known literature hydraulic valve drives.