EFFECT OF DRIVING WHEEL TYPE ON DRAWBAR PULL OF TRACTOR

This paper is focused on the possibility of increasing the drawbar pull of agricultural tractor on the soil and grass-covered surface. From our perspective, we have chosen one available and the cheapest way, i.e. steel boots for tyres of small tractors, and this was compared with a newly developed system of auto-extensible blades next to the wheel. The tractor with steel boots and auto-extensible blades reached a higher drawbar pull on average by 70 % in comparison with tyres

Static Lateral Stability of Tractor with Rear Wheel Ballast Weights: Comparison of ISO 16231-2 (2015) with Experimental Data Regarding Tyre Deformation

The paper presents a static lateral stability of a sub-compact tractor MT8-070 Mini in relation to a safe tractor operation. Axle weight distribution of the tractor was measured to calculate the vertical and longitudinal coordinates of a centre of gravity (COG). Experiments were aimed at the tractor equipped with no and four levels of rear wheel ballast weights (30.5, 61, 91.5 and 122 kg) at standard and extended overall width on tyres. A static overturning angle was calculated and experimentally measured when the tractor with right wheels touching the ground was in a state of unstable equilibrium. Comparing the experimental data with ISO 16231-2 (2015), the differences were 2.57%, 2.80%, 3.04%, 3.42% and 3.88% in the case of the standard overall width on tyres and 2.40%, 2.61%, 3.11%, 3.67% and 3.99% in the case of the extended overall width on tyres at 0, 30.5, 91.5 and 122 kg of the rear wheel ballast weight. Considering the vertical tyre deformation and the lateral shift of the tyre, the differences decreased to 0.95%, 1.11%, 1.29%, 1.85% and 1.42% (standard overall width on tyres) and 0.91%, 1.18%, 1.69%, 2.27% and 2.57% (extended overall width on tyres). The length of a rubber lug of a tyre contact patch did not change when the tractor was inclined at various ballast weights and did not affect the static overturning angle calculation according to ISO 16231-2 (2015). Results showed higher static overturning angle experimentally measured in comparison with calculated according to ISO 16231-2 (2015) due to the tyre deformation. Limiting the tractor operation on the basis of the static overturning angle calculated according to ISO 16231-2 (2015) avoids the tractor usage under dangerous operation conditions

Assessing the Technical Condition of Inspected Vehicles in Reporting Period

Vehicle emissions inspection represents a fast, relatively efective in terms of time and cost, and mainly comprehensive estimation of vehicle emissions. Procedurally, emissions inspection includes those inspection operations that focus not only on analysing exhaust gases but also on detecting the functionality and tightness of other engine components directly afecting the ecological friendliness of inspected vehicle‘s engine. Our study describes the results of vehicles inspected at an emissions inspection station for the reporting period. Based on the analysis of information obtained from the National Transport Authority of the Slovak Republic concerning the evaluation of vehicles according to individual categories, it can be alleged that the technical condition of vehicles of M1 and N1 categories is gradually improving

Analysis of the Effect of Loading Process on Tribological System Properties

The effect of loading on the properties of selected sliding pair is monitored and analysed in the submitted contribution. The obtained results of dynamic loading were also compared with static loading. The experimental tests were performed using the testing machine Tribotestor M10. Steel 11 600 was selected as a material sample for the shaft as it belongs to commonly used materials in the manufacturing of agricultural components of shaft type or pin type. A full-bronze centrifugally moulded bearing shell from the material CuSn12 was selected as the second element of friction pair. Two oils were selected for lubrication of friction node – the mineral gear oil Madit PP80 and ecological oil Plantohyd 46 S. The selected friction pairs were tested in three loading regimes according to the methodology (two dynamic processes and one static process). 60 tribological tests were performed, i.e. 10 for each type of loading and lubrication. The weight losses of the friction pair elements were part of the tracked and analysed parameters. The polluted oil was examined using the ferrographic analysis to verify the weight losses. The abrasion particles of friction pair and their contribution to oil pollution were also analysed. Following the performed experiments different effects of loading regimes may be concluded, essentially in terms of wear size and the number and size of wear particles as well. The obtained results confirmed that the power spectral density of generated signal is probably an important criterion for assessment in terms of simulated random dynamic load in given experiment. In terms of technical application in loading processes – power spectral density is actually the amount of energy supplied to the process

Hydraulic Device for Simulation of Pressure Shocks

This work is focused on the design of a hydraulic device on which simulations of pressure shocks can be performed. The hydraulic device was constructed to allow simulations of pressure shocks transferred directly in operating conditions because simulation programs for hydraulic accumulators have only theoretical values while simulation on the designed hydraulic device enables obtaining specific readings directly in operating conditions that can be set. At the first control measurement on the hydraulic device, there occurred pressure shocks generated by the hydraulic device itself, these pressure shocks being undesirable in hydraulic circuits. In order to eliminate pressure shocks in the circuit, a diaphragm accumulator was added to the hydraulic device and was used to verify the function of simulating pressure shocks and eliminating undesirable pressure shocks. During the second control measurement on the hydraulic device, a reduction of unwanted pressure shocks was shown with the help of added diaphragm accumulator, thus the function of the hydraulic device to simulate pressure shocks was confirmed, which may also refect practical application in hydraulic circuits of mobile machines

Alternative Models for Calculation of Static Overturning Angle and Lateral Stability Analysis of Subcompact and Universal Tractors

Vehicle lateral stability is evaluated using the static overturning angle. The correct value of this parameter depends on the calculation method. The aim of this study was to compare the latest standard with previously published methodology, to propose two alternative methodologies (Models 1 and 2) and to analyze the influence of various levels of rear wheel ballast weights and overall tire widths on the stability of universal and subcompact tractors. The results showed a significant regression effect of the rear wheel ballast weight on static overturning angle. The influence of the rear wheel ballast weight was higher in the subcompact tractor than in the universal tractor due to a larger distance between the height of the center of gravity and the center of the rear axle. Comparing the latest standard with the previously published methodology, the highest difference values were 13.82% and 7.30%. Both models are based on the previously published methodology and differ from each other in rolling and slope lines. The methodology proposed in Model 2 differed from the standard similarly to the previously published methodology; therefore, it is irrelevant. Model 1 reached differences of only −1.81% and −1.63%, representing a minimal difference from the standard

Fatigue Analysis of Spike Segment of Special Tractor Wheels in Terms of Design Improvement for Chernozem Soil

The driving wheels affect the tractive efficiency, fuel consumption, and soil compaction. This study presents the fatigue analysis of a spike segment that is the main part of an innovative driving wheels designed to improve tractor tractive performance. The design improvement was proposed for Chernozem soil allowing the full penetration of spikes. The spike segment was loaded by forces resulting from the maximum drawbar pull at 100% wheel slip and penetrometer resistance. A drawbar pull increase caused by the spike tires was also calculated. The experiments were performed using a subcompact tractor in the first gear on a grass field at soil moisture 18.8%. Gerber theory was used for the fatigue analysis performed using ANSYS software. The dependances of the safety factor on the horizontal rod diameter and the number of load cycles was constructed. The safety factor of 1.73 calculated for the spike segment made of steel S355 is suitable for the reduction of the actual horizontal rod diameter (12 mm). The fatigue analysis showed a safety factor of 1.28 at 100,000 load cycles in the case of a reduced diameter (10 mm). A diameter of 8 mm was also simulated, but the calculated safety factors do not allow it in terms of safe operation

Fatigue Analysis of Spike Segment of Special Tractor Wheels in Terms of Design Improvement for Chernozem Soil

The driving wheels affect the tractive efficiency, fuel consumption, and soil compaction. This study presents the fatigue analysis of a spike segment that is the main part of an innovative driving wheels designed to improve tractor tractive performance. The design improvement was proposed for Chernozem soil allowing the full penetration of spikes. The spike segment was loaded by forces resulting from the maximum drawbar pull at 100% wheel slip and penetrometer resistance. A drawbar pull increase caused by the spike tires was also calculated. The experiments were performed using a subcompact tractor in the first gear on a grass field at soil moisture 18.8%. Gerber theory was used for the fatigue analysis performed using ANSYS software. The dependances of the safety factor on the horizontal rod diameter and the number of load cycles was constructed. The safety factor of 1.73 calculated for the spike segment made of steel S355 is suitable for the reduction of the actual horizontal rod diameter (12 mm). The fatigue analysis showed a safety factor of 1.28 at 100,000 load cycles in the case of a reduced diameter (10 mm). A diameter of 8 mm was also simulated, but the calculated safety factors do not allow it in terms of safe operation

Frequency Spectra Analysis of Drawbar Pulls Generated by Special Driving Wheels Improving Tractive Performance

Driving wheel operation is characterized by force interactions with the ground, manifested in the form of vibrations. Signals generated by driving wheels can be analyzed in the frequency spectrum of tractor drawbar pull. The paper presents the analysis of a drawbar pull signal generated by a tractor equipped with two types of special driving wheels and standard tires. Beside the evaluation of special driving wheels’ properties according to drawbar power, the frequency spectra of measured signals were analyzed using a fast Fourier transformation. The model spectrum intervals for the standard tires, spike tires, and blade wheels were calculated according to the number of rubber lugs, blades, or spikes and compared with the experimental results. The results showed that the specific frequencies typical for blades and spikes were identified in model spectrum intervals. In the case of standard tires, the spectrum components typical for rubber lugs of the tire tread pattern were not identified. The highest amplitude of the typical frequency component was detected in the case of blades wheels, which showed the highest difference in drawbar power in comparison with the standard tires. Smaller dimensions of spikes resulted in lower amplitude and lower difference in drawbar power in comparison with the standard tires