Method for Determining the Pressure of a Pneumatic Wheel on the Soil

A method for determining the pressure of a pneumatic wheel on the soil is proposed. The method consists in measuring the magnitude of the vertical acceleration of the axles of a self-propelled vehicle, its speed and air pressure in the tire. The research results allow the developers of vehicles fitted with pneumatic wheels to choose rational characteristics of tires and optimal parameters of the oscillatory system of wheeled tractors, which help to reduce soil compaction.

A comparative study of static and dynamic properties of honeycomb non-pneumatic wheels and a pneumatic wheel

Three-dimensional finite element (FE) models of the honeycomb NPWs with three different spokes’ configurations, realized by varying the cell angle, were formulated. The validity of the proposed NPW FE models was demonstrated by comparing the predicted wheel responses with the reported data. A FE model of the pneumatic wheel of identical size was also formulated and verified on the basis of the measured vertical force-deflection and cornering properties. The verified NPW models were subsequently employed to study their feasibility through comparisons of in-plane as well as out-of-plane properties with those of the pneumatic wheel. The influences of the cell angle and normal wheel load on the static and dynamic properties of the NPWs were also investigated. The results showed load-dependent longitudinal stiffness of the wheel due to strong coupling between radial and longitudinal deformations of the honeycomb spokes. The lateral stiffness, however, was observed to be load-independent due to negligible coupling between radial and lateral deformations of the spokes. The spokes of the honeycomb NPWs could thus be easily tuned to achieve vertical and longitudinal stiffness comparable to those of the reference pneumatic wheel. The lateral and cornering stiffness of the NPWs with the planar spokes, however, were substantially higher, irrespective of the spokes’ configuration considered. The significantly higher cornering stiffness resulted in rapid saturation of the cornering force of the NPWs at side-slip angles about 1.1°, which is likely to cause lateral sliding of the wheels and potential loss of directional control under higher side slip conditions.

Evaluation of methods for experimental and analytical determination of the contour area of the contact patch of a pneumatic tire with a support base

Subject of study. The results of experiments on the estimation of the error of methods of experi-mental and calculated determination of the contour area for the ecological assessment of a mobile energy device (MED) are presented. There was used the example of modern radial tires 360 / 70R24 of Bel-89 and 18.4R34 of F-11 agricultural tractor MTZ-1025.2. in modes of non-nominal loading at nominal load on tires and changes in tire pressure within the range recommended for field work. The purpose of the study. To assess the possibility of improving the computational method for determining the contour area of the contact patch of the tire tread of a pneumatic wheel based on the mathematical model of V.L. Biederman. Materials and methods. The assessment was carried out for four ways of determining the area of the tire contact patch: 1) directly measuring the area using a digital photograph of the tire contact patch in Kompas-3D V13 software with the de-termination of the scaling and method error using a square from 100x100 mm graph paper; 2) calcu-lation by the formula of the area of an ellipse, using the length and width of the tire contact patch, measured with a tape measure directly from the obtained print; 3) by calculation, determined from the digital photograph in Kompas-3D V13 software; 4) by calculation, determined by calculation using the parameters of the universal tire characteristic (UTC). Results and discussion. As a result of the experiments, it was found that for modern radial tractor tires, the static deformation of which does not exceed 18-22%, the method of theoretical determination of the contour area of the tire contact patch using the UTC parameters can be applied with sufficient (for engineering practice) accuracy. Full convergence of the calculated and experimental contour areas of the tire contact patch can be provided by the coefficient of their ratio. Conclusions. The carried out assessment of the possibility of using methods for calculating the conditional contour area of the tire showed that these methods can be well used for a comparative assessment of the technogenic mechanical impact of propellers on the soil.

World experience and development prospects of mechanization scheme of nuclear power plants construction

Introduction. Improvement of construction methods for the main structures of nuclear power plants (NPP) is impossible without updating the old and developing fundamentally new schemes for mechanization of construction production. Based on the analysis of world experience in using various types of lifting mechanisms at NPP construction sites, it is proposed to assess the current state and perspective for the development of organizational and technological approaches to the development of effective mechanization of construction production in the construction of atomic energy facilities. Materials and methods. Review of domestic and world (UK, USA, Japan) experience in NPP construction allows us to assert that despite the technological and organizational and managerial difficulties, the construction of NPP power units by enlarged units of high factory readiness still remains promising and feasible. The implementation of this approach involves the design and manufacture of unique hoisting mechanisms, the most popular of which are currently crawler or rail-mounted mast cranes. At the same time, the experience of constructing nuclear power plants of the USSR and Great Britain using gantry cranes was undeservedly forgotten. Results. The performed comparative analysis of the applicability of tower, mast and bridge (gantry) types of cranes allows us to recognize the high complexity of using gantry cranes in the construction of NPPs and the structural limitations of other types of cranes. The main disadvantages of gantry cranes lie in their use of a rail track, the replacement of which with a pneumatic-wheeled chassis, which has undergone significant development in the last 20 years, can open up new perspective for the reengineering of previously used mechanization schemes for NPP construction. Conclusions. Using main lifting mechanism of an overhead crane equipped with a pneumatic wheel chassis in the construction of nuclear power becomes one of the most promising options in the development of nuclear energy construction. The development and implementation of new schemes for the mechanization of construction production based on experience and advanced technologies in mechanical engineering can provide a qualitative improvement of the ongoing investment and construction activities in the field of nuclear energy.

Can Airless Tyres Eliminate Caravan Fishtailing

A tyre blow-out on a caravan can be disastrous, even fatal in severe situations. A non-pneumatic wheel (NPT) has the obvious advantage of being resistant to the DREADED FLAT TYRE. Thus, there is promise of safety. A number of tyre manufacturers have been busy developing a tyre or complete wheel to capitalize on this benefit. The best-known NPT is dubbed the TWEEL®. The nomenclature of Michelin’s NPT is a joining of parts of the two words, Tire and Wheel. The TWEEL® has application to skid-steer loaders and commercial lawn mowers. Michelin encountered problems in the development of the TWEEL® for high speed use. One of these problems encountered by Michelin in the development of the Tweel may be a god-send for caravan wheels as they develop their new NPT for highway use. The design of the so-called UPTIS® is not just an improved version of the TWEEL® but a completely different operating philosophy. This paper considers the evolution of the NPT and considers how it might be beneficial in the caravan context. To illustrate, a fishtailing tale to tell gets told.

THE TRACTION MECHANICS OF A BULLDOZER WITH PNEUMATIC PROPULSION SCHEME 44 AND BLOCKED ACTUATOR IN THE DEVELOPMENT OF SOIL

The task of the work is to assess the traction capabilities of a wheeled bulldozer when digging the soil in connection with the specifics of its pneumatic-wheeled propulsion and drive of the driving wheels, since publications on this topic are not complete enough. And for this it is necessary, first of all, to further highlight some issues of traction mechanics of these machines, using the material developed by the authors. Due to the complexity of solving all the problems of traction mechanics of a wheeled bulldozer purely analytical way in the work applied analytical-graphical method, which allowed some traction indicators to Express through others, using their graphical dependencies, built on analytical formulas through the General third indicators, by their further exclusion. The object of research is a bulldozer having a pneumatic wheel drive with a wheel scheme 44 and a blocked drive them. The process of functioning of the bulldozer is considered. Traction mechanics of the bulldozer including questions of statics, kinematics, dynamics and management of process of development of soil taking into account specifics of work of its pneumocycle mover is investigated.