The use of alternative fuels remains an important factor in solving the problem of reducing harmful substances caused by vehicles and decarbonising transport. It is also important to ensure the energy efficiency of vehicle power plants when using different fuels at a sufficient level. The article presents the results of theoretical and experimental studies of the conversion of diesel engine to alternative fuels with hydrogen admixtures. Methanol is considered as an alternative fuel which is a cheaper alternative to commercial diesel fuel. The chemical essence of improving the calorific value of alternative methanol fuel was investigated. Studies showed that the energy effect of burning an alternative mixture with hydrogen additives exceeds the effect of burning the same amount of methanol fuel. The increase in combustion energy and engine power is achieved as a result of heat from efficient use of the engine exhaust gases and chemical conversion of methanol. An experimental installation was created to study the work of a converted diesel engine on hydrogen–methanol mixtures and thermochemical regeneration processes. Experimental studies of the energy and environmental parameters of diesel engine converted to work on an alternative fuel with hydrogen admixtures have shown that engine power increases by 10–14% and emissions of harmful substances decrease.

Recently in many cities of the world began to introduce so-called «metrobus» or BRT (Bus Rapid Transit) systems, which became a cheaper alternative to the metro and other rail transport, in particular trams. The aim of the work is to determine the stability indicators of the metrobus in the transitional traffic modes, in particular when performing such manoeuvres as «steering wheel jerk» and «shuffle». For this purpose, the equations of metrobus plane-parallel motion are supplemented by equations of the links of the road train in the vertical plane by halopilation (tangage, trim) and roll.The critical straight-line speed of the three-link metrobus has been determined, which was 32,06 m/s, and this speed is independent of the corners of the steering wheels of the bus and the trailer links.It has been shown that as the steering wheel angle of the bus increases, the difference in the folding angles of the bus increases, with the second folding angle significantly exceeding the first, especially considering the roll of the metrobus body. It has been established that the greatest rolls and loads of the metrobus axles are those of the last trailer, which is the limiting factor for the critical speed. The lateral accelerations of individual metrobus links and their yaw velocity when performing the manoeuvre «steering wheel jerk» and «shuffle, Sl = 24 m», show that both the bus and the second trailer link are a limiting factor when performing various manoeuvres, but the acceleration value does not exceed the permissible 0,4g, so its stability under these conditions is ensured.

In recent years, the development of container transportation served as a powerful impetus for increasing the length of vehicles, especially road trains, which is due to a number of advantages regarding the transportation of large-sized freight in a container. Today, the whole range of containers is transported by two-link road trains consisting of a tractor vehicle and semi-trailer. The efficiency of such transportation can be increased by means of three-link road trains capable of transporting either three (two 20-foot and one 40- or 45-foot) or four 20-foot containers. This organization of transportation will lead to energy savings and a reduction in environmental pollution due to the reduction of vehicles. However, there is a problem with the maneuverability and stability of such vehicles. The paper developed a kinematic model of three-link road train type “B-triple” with steered axles (front or rear) of semi-trailer dolly with a dual drive control for these axles. Based on folding angles of road train links and drive control transmission ratios of the axles of semi-trailer dolly, the main indicators of road train maneuverability are determined – road train links trajectories displacement relative to the vehicle trajectory and road train overall traffic lane. It was established that when entering a turn with slight differences in folding angles of road train links, the steered axles of semi-trailer dolly turn in the direction opposite to the direction of a turn, thereby reducing the overall traffic lane. During circular motion, the overall traffic lane of road train with steered semi-trailers decreased by almost 2 m, but such road train does not meet the maneuverability requirements. The search for ways to improve the maneuverability of three-link road trains should be sought in the designs of three-link road trains.

The paper focuses on selected issues in modern public transport systems, which are increasingly seen as an important means of enhancing safe populations mobility, especially in urban areas suffering from growing traffic congestion. This is facilitated by the introduction of a new bus traffic system "Bus Rapid Transport" (BRT), which is the result of the bus public transport network development. The rolling stock used in the BRT system is of two types: the first one is a classic, two-link or three-link metrobus with an engine that runs on both diesel and gas fuel, as well as a hybrid electro-gas engine. These options are inherent to articulated buses, 18 and 24 meters in length. The second type is a bus train consisting of a bus and one or two trailers, or one or two buses. Therefore, the purpose of the studies is the possibility of creating a bus train based on three “Bohdan” buses. Special attention is paid to the maneuverability and movement stability, taking into account specific bus characteristics in large cities. For this purpose, the bus train consisting of three similar buses mathematical model was improved, with which the maneuverability and movement stability are determined. It was established that during the road train circular movement and the first bus steering wheels turning at the place where trailer links maximum displacement is achieved, the overall traffic lane width will be 6.7 m, which is much less than the permissible one, that is, the maneuverability of a bus train based on three “Bohdan” buses is not a limiting factor for its operation on urban routes.

The presence of a bogie in three-axle vehicles when moving along a curved trajectory leads to deterioration in its handling and maneuverability. The paper developed a mathematical model of the elastic bogie wheel while moving along a curvilinear trajectory, according to which the bogie wheel simultaneously participates in curvilinear and plane-parallel motion with a slip angle. Such movement of the bogie wheels develops significant lateral and longitudinal forces on the steered wheels, which leads to the movement of the steered wheels with slip, redistribution of the load on them, tire twisting, and a decrease in the steering angle of the outside steered wheel due to the elasticity of the steering trapezoid. Based on the mathematical model of the bogie wheel, an analytical dependence was obtained to determine the minimum turning radius of a three-axle vehicle. The reliability of the analytical dependencies characterizing the movement of the bogie wheel along a curvilinear trajectory was determined by comparing the minimum turning radii of a three-axle vehicle with the intermediate axle lowered and raised. It has been established that the minimum turning radius of a vehicle with a bogie increases compared to a two-axle vehicle and depends on the cornering stiffnesses of the tires of the bogie and steered wheels, the bogie and vehicle wheelbases, the kinematic and elastic parameters of the steering trapezoid, the direction of turning of the steered wheels, and the load on the steered and the bogie wheels.