Single-axle Trailer Research Articles

Assessment of the Performance of Agricultural Tires Using a Mobile Test Bench

The performance of agricultural tires varies with the characteristics of both the terrain and the tractors on which they are mounted, which differently affect the rolling resistance, the traction capacity, and the slip. To reduce the variability of test conditions, CREA developed an original mobile test (MTB) bench which consists of a dynamometric single axle trailer pulled by a tractor and can be used both in traction performance tests (driving wheels) and in rolling resistance tests (driven wheels). A control system alternatively operates the adjustment of traction force or slip, so that each test is performed maintaining constant the desired values. The MTB underwent tests under different conditions (type of surface, pre-set values of force of traction and slip) aimed at verifying its accuracy and reliability. In a final test, two pairs of identical new tires were simultaneously mounted on the MTB and on the rear axle of the 2WD tractor that pulled it, to discover information on the different interactions occurring, under the same traction conditions, between the soil surface and each pair of tires, with reference to the relationship between the slips and the load transfers observed on the MTB and on the tractor rear axle. The results evidenced the capability of the MTB to guarantee repeatable test conditions, including field conditions, allowing comparison among the performance of different tires.

Experimental Research of Vibrational Properties of a Single-Axle Trailer when Crossing an Individual Road Obstacle

Abstract Investigation of road vehicles in term of their dynamics is very important task. There are assessed two main points of view, i.e. the driving safety and ride comfort for passenger. This article is aimed at analysis of dynamics of a single-axle trailer by means of real tests. Several driving manoeuvres have been performed and evaluated, at which, when a trailer has been towed by a passenger car. As the main output parameters, acceleration signals have been measured and recorded. The vehicle-trailer combination has been moved at several driving speeds.

Mathematical model for farm tractors towing single axle trailer rollover prediction

Mathematical model for farm tractors towing single axle trailer rollover prediction

Mathematical model for farm tractors towing single axle trailer rollover prediction

Mathematical model for farm tractors towing single axle trailer rollover prediction

Influence of braking on dynamic stability of car-trailer combinations

The influence of braking on dynamic stability of a car-trailer combination (CTC) is studied in this paper. The braking is simply modeled and integrated into a single-track model (STM) with a single-axle trailer. On this basis, some fundamentals and analysis results related to system dynamic stability are given through simulation. Furthermore, it is found that the axle load transfer and braking force distribution have a great influence on system dynamic stability. In order to further analyze the influence of these two factors, both of the braking force distribution and the pitch motion are considered in the modeling. Finally, the ideal braking force distribution domain is proposed. Results can be adopted to explain the experimental phenomenon and serve as a guideline for the differential braking strategy in stability control of the CTC.

Research of operation safety and maneuverability of agricultural low-tonnage road train under critical traffic conditions

The article considers conditions for safe operation of low-tonnage road trains with overall trailers, namely universal platforms with a load capacity of up to 3 tons, capable of transporting agricultural machines, mini-factories and other equipment, as well as tourist houses. Transportation of such trailers on wheels is associated with high risks arising at small turning radii and emergency braking. (Research purpose) The research purpose is in improving the safety of operation and maneuverability of agricultural low-tonnage road trains operating in difficult road and terrain conditions of agricultural production. (Materials and methods) Authors have analyzed the results of research and experiments on the safe operation of low-tonnage road trains with trailers weighing up to 1 ton. The authors developed and tested on the basis of VIM and the Volga State Technical University a mechanical coupling device with a flexible connection that increases the handling and maneuverability of the trailer. (Results and discussion) The authors determined that the critical turning radii depending on the speed of a low-tonnage road train in different road conditions and different loading of the trailer when driving in front and rear for a conventional single-axle trailer with a load capacity of 1.5; 2; 2.5; 3 tons. It was found that the maneuverability is largely provided by the additional force in the cable, so authors recommend using a cable with a diameter of at least 9 mm. (Conclusion) Further research will make it possible to determine the critical indicators of safe operation of a low-tonnage road train with a load capacity of up to 3.5 tons: safe speed when passing critical turns, emergency braking and reversing.

BACKING UP A TRAILER – AN APPLICATION-BASED VECTOR ANALYSIS PROJECT FOR 2ND YEAR CALCULUS

Abstract – A project for the second year calculus course, ME201, will be presented. Students worked in groups, make measurements using physical prototypes and performed analysis to predict behavior for the physical situation of reversing (backing up) a vehicle attached to a single axle trailer. The objectives of the project were to reinforce concepts from previous courses, including physics (vector components) and linear algebra (matrices), to demonstrate key concepts from the current course (vector products, moment vector), and to generate interest in future courses (sensors and feedback, control systems). This paper will outline the development process for the project, including the design and fabrication of the physical prototypes and the selection of test conditions. Measurements and analysis from the project, including samples of student work, will be presented.

Dynamical behavior of universal rocket transportation launching device on rough road with discrete obstacles

Functioning of the universal rocket transportation launching device in its transportation mode is analysed in the paper. The device the main function of which is to launch rocket targets used in the training process of the anti-aircraft missile systems operators needs to function effectively in transportation mode as well – it has to move with relatively high speeds in training fields maintaining sufficient stability parameters of the rocket target movement. The universal rocket transportation launching device in transportation mode is modeled as a single axle trailer with a rocket target – long cylinder attached to it by suspension represented in the form of lumped parameter elastic damping elements. Dynamical models for the analysis of its vertical and roll motion dynamics were constructed and the corresponding mathematical models derived. The excitation signal reconstructing motion of the wheels traversing discrete cleats was applied. Crossing of the longitudinally shifted left and right-side cleats was identified as the worst case from the viewpoint of rocket target motion parameters stability. The obtained results are used for rocket target suspension development.

Effect of Lateral Slope and Loading Pattern on Static Stability of Single Axle Trailer

Single axle trailers are most common means of transportation in rural areas. For maintaining stability of tractortrailer system, it is necessary to ascertain different factors and forces which disturb equilibrium during transportation. The effect of operating conditions and design parameters of single axle trailers on its stability were analysed using scaled physical model under static conditions. Static load tests on varying slopes were carried out using scaled physical model to determine the variation in load pattern on the trailer tyre and its hitch point. The angle of inclination along with the normal load influenced the load shift from outer wheel to inner wheel, causing instability of the tractor-trailer system. The axle position had a paramount effect on vertical hitch load. Hitch length and axle position were two major design considerations that ensured proper distribution of normal load. A normal load less than 4273 N, and the centre axle position of trailer was safe operating conditions for tractor-trailer system at lateral slope (angle of inclination) of less than 15 degrees.

Static Tip-Over Stability Analysis for a Robotic Vehicle With a Single-Axle Trailer on Slopes Based on Altered Supporting Polygons

This paper analyzes the effect of towing a single-axle trailer on static tip-over stability for field mobile robots on slopes. For this purpose, this study defines altered supporting polygons (ASP) for both tractor and trailer. These ASPs are based on a force-torque static equilibrium analysis that reshapes the corresponding ground contact supporting polygons. In this way, it is possible to estimate tip-over stability for each unit separately by projecting its center of gravity onto its ASP, even in the case that both bodies have different inclinations. Online implementation issues and simulation results are discussed. Moreover, a case study is presented for the Alacrane mobile manipulator, which carries a trailer for power generation.

Field tests and validation of dynamical models of tank vehicles Part I: mathematical model and experimental apparatus

This paper presents an experimental investigation of the handling performances of an articulated vehicle carrying liquid cargo. The test vehicle consists of a car with a single-axle trailer carrying a cylindrical tank, fully instrumented to measure the interested parameters of vehicle dynamics and liquid-vehicle interactions. An original device for the visualisation of the liquid free surface inside the tank is also described. Besides, the authors present a simplified model of articulated vehicle carrying liquid cargo and a comparison between experimental data and model results.

Dynamic Behaviour of a Tractor–trailer Combination during Braking

Both the theoretical and practical aspects of braking in a tractor and single axle trailer combination were examined using appropriate tests that also measured other behavioural characteristics of the combination. The results showed that braking distance or deceleration can be calculated accurately but the actual braking behaviour on icy roads can currently be determined only by testing. The results also showed that the test standards for agricultural trailer brakes can give erroneous results when single axle trailers are used. Future standardisation work in single axle trailers should employ modified test procedures. In standards and legislation, braking performance is often determined by the stopping distance or deceleration value. For brake performance the braking ratio can be calculated from the axle load and deceleration. This value gives a better figure for the torque capacity of the trailer brakes and in brake performance tests should be used instead of stopping distance or deceleration values.

Design and Testing of an Electric-Powered Walking Tractor

The walking tractor, driven by an internal combustion engine, plays an essential role in agricultural mechanization in Italy, both on small farms and in growing houses. But its utilization is associated with high levels of noise and vibration and in closed environments such as greenhouses or plastic film houses, with the presence of exhaust engine gases. The result is extremely severe working conditions for the operators. To reduce these problems two electrically driven walking tractors have been designed and built: the first, with a rated power of 3 kW is driven by alternating current (a.c.) with a power cord and the second, with a rated power of 2 kW is driven by a direct current (d.c.) by means of accumulator batteries. Soil preparation tests were made and showed little difference in the cultivation achieved compared with engine-driven machines. The machines have also been used on turkey farms for periodically breaking up the surface layer and mixing the litter. High labour productivity (500 m 2/h per worker) and 30% sawdust saving for litter were obtained. The d.c. walking tractor has been tested in transport (1·5 h of battery life at 5·5 km/h) and mowing operations (work rate of 0·15-0·18 ha/h), using a coupled single-axle trailer and a mowing bar, respectively.

A mathematical model of the effect of trailers on tractor ride vibration

The effect of an unbalanced, single axle trailer on tractor ride vibration behaviour is studied using a two dimensional, nine degree of freedom mathematical model. Predicted results for the combination of a tractor, without a suspension, and a trailer indicate that a vertical hitch suspension would improve ride comfort and has parameters which could be achieved in practice. Hitch compliance in the longitudinal direction offers no benefits and free play should be avoided. For a tractor and trailer combination fitted with axle suspensions, the hitch should be attached to the tractor body and should not incorporate any compliance.