Dependencies of the lead of front driving wheels on different tire deformations for a MFWD tractor

Tractors are the main machines in agricultural production processes. Agricultural tractors commonly employ a four-wheel drive transmission. To reach maximum efficiency in production works, tractors are loaded by as high thrust as possible. The consequence of it, quite often, is that the slippage of driving wheels grows to the limit that is not allowed. To reduce the slippage, various ways are pointed out in terramechanics. One way is to increase the tractor’s weight by adding ballast. The other way is to increase the contact area between tires and the supporting surface. The slippage can be also reduced with traction control and other relevant systems. These methods, which help to reduce slippage, also affect tire deformation. When proportion of tires deformation is not the same as proportion of their sizes, the consequence is change of the lead of front wheels. In this paper analysis is presented, how the lead of front wheels affects the work of MFWD tractor in different conditions. Test results are presented for a MFWD tractor, how the lead of front wheels varies depending on deformation ratios between front and rear tires. For a MFWD tractor, values of deformation ratio between front and rear tires were determined, which ensured effective and which produced unreasonable values of lead of front wheels. First published online: 17 Jul 201

Vidutinės galios MFWD traktorių eksploatacinių ir aplinkosauginių rodiklių gerinimas įvertinant padangų deformacijas

The aim was theoretically and experimentally based approach of selection tires inflation pressure for the MFWD tractor normalization slippage, while ensuring a minimum kinematic mismatch between front and rear drive-wheels, thereby for reducing fuel consumption and environmental impact. The object of this research is the selection of tires inflation pressure and their correct deformations for the medium power MFWD tractor with locked drive-axles and estimated wheels vertical load.Teoriškai ir eksperimentiškai pagrįsti metodą traktoriaus oro slėgių padangose parinkimui, normalizuojant buksavimą, tuo pačiu užtikrinant minimalų kinematinį nesutapimą tarp traktoriaus MFWD priekinių ir galinių varančiųjų ratų, taip sumažinant degalų sąnaudas bei žalingą poveikį aplinkai. Darbo uždaviniai 1. Išnagrinėti traktoriaus MFWD su blokuota keturių varančiųjų ratų pavara buksavimo reguliavimo galimybes ir kinematinio nesutapimo atsiradimo priežastis. 2. Atlikti traktoriaus 4x4 varančiųjų ratų kinematinio nesutapimo atsiradimo teorinę analizę ir sudaryti modelį oro slėgiams padangose parinkti, kuriems esant kinematinio nesutapimo koeficientas būtų artimas vienetui. 3. Nustatyti traktoriaus 4x4 varančiųjų ratų kinematinio nesutapimo bei degalų sąnaudų priklausomybes nuo padangų deformacijų dėl traktoriaus balastavimo ir oro slėgio padangose variacijų. 4. Atlikti traktoriaus MFWD eksperimentinius eksploatacinių rodiklių priklausomybių nuo oro slėgių padangose ir balastinės masės variacijų tyrimus, normalizuojant traktoriaus buksavimą pagrindiniuose lauko darbuose. 5. Normalizuojant traktoriaus MFWD buksavimą, atlikti eksperimentinių eksploatacinių rodiklių priklausomybių oro slėgio padangose ir balastinės masės variacijų tyrimus dirbančio 4x4 ir sudvejintais ratais 2x4 režimais.Žemės ūkio akademijaVytauto Didžiojo universiteta

Traktoriaus balastavimo, oro slėgio padangose ir jų deformacijų sąveika

Vytauto Didžiojo universitetasŽemės ūkio akademij

How to select air pressures in the tires of MFWD (mechanical front-wheel drive) tractor to minimize fuel consumption for the case of reasonable wheel slip

In agriculture, tractor is the most fuel-consuming machine. The research indicates that 20–55% of available tractor power is lost in the process of interaction between tires and soil surface. Tire pressure and vertical wheel load are both easily managed parameters, which play a significant role in controlling the slip, the traction force and the fuel consumption of a tractor. The purpose of the research was to base theoretically and experimentally the tire pressures that ensure a minimum kinematic mismatch between the drive wheels for MFWD (mechanical front-wheel drive) tractor, and thereby reduce the fuel consumption at a reasonable tire slip. Close to one coefficient of kinematic mismatch between the front and the rear wheels was observed when combinations of pressures in the rear/front tires were made, respectively: 150/70, 190/110, and 230/115 kPa. When tractor (MFWD) was driving on a hard road surface without thrust load and with above mentioned tire pressure combinations, the lowest fuel consumption was reached, namely, in the range from 3.75 to 3.8 L h−1Vytauto Didžiojo universitetasŽemės ūkio akademij

The influence of driving double wheels to the slippage of tractor

The article inspects the influence of tractor driving double wheels to the driving and rolling resistance forces and also to slippage. Experimental study made with the tractor aggregate, consisting of a tractor "MTZ-82.1" with single and double driving wheels and the trailer "2PST-4" with 4 tons cargo. The measurements were made from the making a move, accelerating and constant (fixed) speed regime of aggregate. There are presented the dependences of slippage of tractor driving wheels, when tractor drives with single and double wheels in two fields with different stubble dampness. There is analysing how the doubling of wheels changes the efficiency of tractor driving wheels. There is observed the tractor drives conditions in which the doubling of driving wheels is purposefulVytauto Didžiojo universitetasŽemės ūkio akademij

Traktorių darbo efektyvumas ir galios šuoliai

Vytauto Didžiojo universitetasŽemės ūkio akademij

Differences in tractor performance parameters between single-wheel 4WD and dual-wheel 2WD driving systems

Vertical wheel load and tire pressure are both easily managed parameters which play a significant role in tillage operations for limiting slip which involves energy loss. This aspect to a great extent affects the fuel consumption and the time required for soil tillage. The main focus of this experiment was to determine the effect on the wheels’ slip, the fuel consumption and the field performance of a tractor running in a single-wheel 4WD driving system and in a dual-wheel 2WD driving system, due to the variations in air pressure of the tires as well as in the ballast mass. With no additional mass, the lowest fuel consumption was reached by a tractor with the least air pressure in the tires and running in a dual-wheel 2WD driving system. It was determined that for a stubble cultivation with a medium-power (82.3 kW) tractor running in a dual-wheel 2WD driving system, the hourly fuel consumption was by 1.15 L h−1 (or 7.3%), the fuel consumption per hectare by 0.35 L ha−1 (or 7.9%) and the field performance by 0.05 ha h−1 (or 1.25%) lower compared to a single-wheel 4WD driving system, when driving wheels’ slip for both modes was the same, i.e., at 8–12%Vytauto Didžiojo universitetasŽemės ūkio akademij

Influence of Extra Weight and Tire Pressure on Fuel Consumption at Normal Tractor Slippage

Tire pressure and wheel load are both easily managed parameters which play a significant role in tillage operations for limiting slip which involves energy loss. To a great extent, this aspect affects the fuel consumption and the time required for soil tillage. The study was focused on the tire pressure and extra weight variation effect on fuel consumption and work productivity for soil tillage at normal tractor wheels slippage (7-15%). The experimental research unit composed of an 82.3 kW 4WD tractor and a reversible 4-bodies plough is presented. Tests were carried out on a stubble loam, where slip of tractor driving wheels was 15%, tractor front ballast mass was varied in the range from 0 to 520 kg and inflation pressure in the tires from 240 kPa to 100 kPa. Dependences of tractor performance indicators on ballast mass and tires inflation pressure are presented. When tractor tire slip varies in the range from 7 to 15 percent (which is normal slip in the soil), reducing the tires inflation pressure decreases the driving wheel slip and fuel consumption, while increases work productivity. Increasing the additional mass of the tractor (adding ballast weights) decreases the driving wheel slip, increases work productivity, but also increases fuel consumption and soil compactionVytauto Didžiojo universitetasŽemės ūkio akademij

Traktorių su keturiais varančiaisiais ratais padangų oro slėgio poveikis ratų kinemetiniam nesutapimui

Straipsnyje analizuojamos traktorių su keturiais varančiaisiais ratais varančiųjų ratų kinematinio nesutapimo priežastys. Vienas iš svarbiausių eksploatacinių veiksnių yra ryšys tarp priekinių ir užpakalinių ratų padangų oro slėgio bei ratų vertikaliųjų apkrovų. Kintant padangų oro slėgiui ir ratų apkrovoms, kinta priekinių ir užpakalinių ratų riedėjimo spinduliai, todėl traktoriaus transmisijoje gali atsirasti galios cirkuliacija. Ji priklauso nuo priekinių ir užpakalinių ratų teorinių greičių skirtumo. Straipsnyje išanalizuota keturių ratų varomo traktoriaus tiesiaeigio judesio dinamika. Galios cirkuliacija tarp priekinio ir užpakalinio varančiųjų tiltų yra sąlygojama ratų slydimo. Tuomet dinamikos teorinis tyrimas atliekamas nagrinėjant traktoriaus galios balansą ir pagrindžiama galios cirkuliacija išilginiame plane. Bandymais siekiama nustatyti ryšį tarp padangų oro slėgio, ratų vertikaliųjų apkrovų ir varančiųjų ratų teorinių greičių kinematinio nesutapimo. Darbo tikslas buvo nustatyti keturių ratų varomo, traukos jėga neapkrauto traktoriaus ratų slydimo pasireiškimą ir dydį. Pateiktos ratų buksavimo, slydimo ir kinematinio tarpusavio nesutapimo teorinių greičių priklausomybėsIn the article causes of kinematic mismatch of four-wheel-drive tractor were reviewed. One of the most important operating characteristics is the relationship between tire inflation and vertical load of the wheels. Due to changes in inflation pressure and tire load, variations in rolling radiuses of the front and rear wheels can cause power circulation in the tractor transmission. This power circulation is dependent on the difference between theoret-ical speeds of front and rear wheels. In the paper, dynamics of a four-wheel-drive tractor performing a rectilinear motion is analyzed. Power circulation between the front and rear driving axles is determined, tacking into account slipping of the wheels. Then dynamic study is conducted to achieve power balance of tractor and put in evidence power circulation in longitudinal plan. Experiments were carried out to establish relationship between tires’ inflation, vertical load and kinematic mismatch with theoretical speeds of driving wheels. The purpose was to determine the effect of additional slip on four-wheel-drive tractors operated without drawbar pull. Dependences of wheels’ slippage and kinematic mismatch with theoretical speeds are presentedVytauto Didžiojo universitetasŽemės ūkio akademij

Effect of variations in front wheels driving lead on performance of a farm tractor with mechanical front-wheel-drive

WOS:000430900300003Most previous researches indicate that about 20–55% of available tractor power is lost in the process of interaction between tires and soil surface. Vertical wheel loads and tire performance are parameters that play a significant role in controlling slip and fuel consumption of a tractor. Tractor’s slip is adjusted by attaching additional weights and/or reducing tire pressures, and this may have an impact on driving lead of front wheels. Mechanical Front-Wheel-Drive (MFWD) tractors work efficiently when driving lead of front wheels is 3–4% in soft soil and 1–2% in hard soil. This research was aimed to experimentally determine such tire pressures that allow adjusting tractor’s slip without deviating from set value of driving lead of front wheels. The research was also aimed to determine the effect of driving lead of front wheels on MFWD tractor’s slip and fuel consumption. Experimental results showed that front/rear tire pressure combinations that generate a well-targeted driving lead of front wheels have no effect on slip on hard soil; however, it significantly affect fuel consumption. Results show that when air pressures in front/rear tires varied within 80–220 kPa, driving lead of front wheels varied in the range from +7.25% to −0.5%Vytauto Didžiojo universitetasŽemės ūkio akademij