2WD Tractor Research Articles

Repair and maintenance costs of 4WD tractors and self propelled combine harvesters in Italy

Purchasing and maintaining tractors and operating machines are two of the most considerable costs of the agricultural sector, which includes farm equipment manufacturers, farm contractors and farms. In this context, repair and maintenance costs (R&M costs) generally constitute 10-15% of the total costs related to agricultural equipment and tend to increase with the age of the equipment; hence, an important consideration in farm management is the optimal time for equipment replacement. Classical, R&M cost estimation models, calculated as a function of accumulated working hours, are usually developed by ASAE/ASABE for the United States operating conditions. However, R&M costs are strongly influenced by farming practices, operative conditions, crop and soil type, climatic conditions, etc. which can be specific for individual countries. In this study, R&M cost model parameters were recalculated for the current Italian situation. For this purpose, data related to the R&M costs of 100 4WD tractors with engine power ranging from 59 to 198 kW, and of 20 SP combine harvesters (10 straw walkers combines and 10 axial flow combines) with engine power ranging from 159 to 368 kW working in Italy were collected. According to the model, which was obtained by interpolating the data through a two-parameter power function (proposed by ASAE/ASABE), the R&M cost incidence on the list price of Italian tractors at 12,000 working hours (estimated life of the machines) was 48.6%, as compared with 43.2% calculated through the most recent U.S. model while, for self propelled combine harvesters, the R&M cost incidence at 3,000 working hours was 23.1 % as compared with 40.2% calculated through the same U.S. model.

Repair and maintenance costs of 4WD tractors and self propelled combine harvesters in Italy

Repair and maintenance costs of 4WD tractors and self propelled combine harvesters in Italy

A model and comparison of 4-wheel-drive fixed-chassis tractor rollover during Phase I

A general model to predict quasi-static articulated tractor instability on a slope has been derived using kineto-static modelling. Under simplifying assumptions, it is possible to model fixed-chassis tractors and, in particular, include the effect of front axle-wheel mass. The model is therefore used in this paper to investigate the effect of front body mass on tractor stability and behaviour during Phase I rollover. The results are of particular relevance to four-wheel-drive (4WD) tractors. The change in potential energy for fixed-chassis tractors during Phase I rollover is also evaluated. The effects of mass partitioning are displayed graphically. It is shown that the stability of a tractor depends on the position of the centre of gravity (COG) of the main (posterior) body. For tractors with massive front wheels, tyres and beam axles, this COG is likely not to be the same as that found from the standard COG methods currently adopted. • Parametric model of tractor rollover initiation for tractors with front mass. • Mass partition properties of tractors important for stability calculation. • Model predicts effect of front mass is significant in terms of stability. • Application of brakes to all wheels potentially reduces full rollover likelihood.

Repair and Maintenance Costs of 4WD Tractors in Northern Italy

Abstract. Purchasing and maintaining tractors along with other machines are two of the most considerable costs for the agricultural sector, which includes farm equipment manufacturers, farm contractors, and farmers. Repair and maintenance costs (R&M costs) typically account for 10% to 15% of the total costs related to agricultural equipment and tend to increase with equipment age. Hence, an important decision in farm management is the optimal time for equipment replacement. Classical R&M cost estimation models, calculated as a function of accumulated working hours, have been primarily developed for U.S. operating conditions. However, R&M costs are strongly influenced by farming practices, operating conditions, crop and soil type, and climatic conditions, which can be specific for individual countries. In this study, R&M cost model parameters were recalculated for the current Italian situation. A complete dataset related to the R&M costs of 100 4WD tractors in northern Italy, including 43 tractors owned by farmers and 57 tractors owned by contractors, was collected. Based on these data, the classical R&M cost estimation model was refined with the purpose of assisting manufacturers in commercial assessment of the domestic market and supporting Italian farmers in their decisions about purchasing new tractors. The main model result indicated that the R&M cost incidence on the price of Italian tractors at 12,000 working hours (the estimated life of local tractors) was 48.6%, compared to a value of 43.2% obtained with the original model formulated for U.S. operating conditions. Further, R&M costs were higher for tractors owned by farmers compared to tractors owned by contractors, at 55.4% of the list price at 12,000 working hours compared to 45.7%.

Design of digital weight transfer display for agricultural tractors

A microcontroller based digital display unit was developed for 2WD agricultural tractors to measure and display the weight transfer from tractor front axle. The device includes a transducer for measuring the tractor front end reaction, an amplifier to amplify the transducer signal and a microcontroller to calculate and display the weight transfer from the front axle. The developed device can be mounted on any make and model of 2WD tractor. The digital display unit was rigorously tested in the laboratory as well as in the field. A maximum of + 3.5% variation in weight transfer was observed between the theoretically calculated and experimentally observed values. Key words: Microcontroller, weight transfer, ring transducer, tractor, front axle.

A device to measure dynamic front wheel reaction to safeguard rearward overturning of agricultural tractors

A microcontroller based system was developed for 2WD agricultural tractors to measure and display the dynamic soil reaction against the front wheels. The device includes a transducer for measuring the tractor front end reaction, an amplifier to amplify the transducer signal and a microcontroller to calculate and display the weight retained on the front axle. The developed device can be mounted on any 2WD tractor. The digital display unit was tested in the laboratory as well as in the field. A maximum of +3.74% variation in dynamic front wheel reaction was observed between the theoretically calculated and experimentally observed values under field conditions.

Automatic wheel slip control system in field operations for 2WD tractors

A microcontroller based automatic wheel slip control system was designed and developed for 2WD tractors. The system continuously measures wheel slip under field conditions and generates commands for depth adjustment if the wheel slip falls outside the desired range. Wheel slip was calculated using the actual and theoretical speeds of the tractor obtained by measuring the rotational speed (rpm) of front and rear wheels, respectively. The developed system was installed on a test tractor and the performance was evaluated with different implements under varying field conditions. The performance data indicated a significant reduction in fuel consumption per hectare (20–30%), increase in field capacity (7–38%), and gain in tractive efficiency (4–10%) with slip control system versus the existing draft control system. The slip control system is also expected to reduce the operator’s effort as it adjusts the depth control lever automatically in response to variation in the soil conditions within the field.

Determination the draft ranges at which 2WD and 4WD tractors operates at their maximum traction efficiency

SUMMARY This research was conducted on 2WD and 4WD tractors to determine the draft force ranges at which these tractors work at their maximum traction efficiency. Massy –Ferguson tractor of 2WD and 4WD type was used in the experiments. The total weight of the tractor is 48.85kN. The weight acting on the rear and front wheels is 34.63kN and 14.22kN respectively. The rated engine power is 95kW. The experiments were conducted using four tractor forward speeds G1(0.39), G2(0.51), G3(0.72) and G4(1.20) m/sec and six operating depths (10, 20, 30, 40, 50 and 60cm) for the plow which used to load the tractor engine. The results showed that the maximum traction efficiency of 2WD and 4WD tractors are 0.72 and 0.79 which occurred at traction wheels slip of 12% and 7% respectively. The draft force range of 4WD was wider than that of 2WD which gives 4WD tractor superiority on 2WD tractor. These draft force ranges are 15-30kN and 12.5-32.5kN and these ranges occurred at wheels slip ranges of 10-30% and 5-19% for 2WD and 4WD tractors respectively. The optimum traction efficiencies ( the optimum tractor performance) are 0.78 and 0.85 and they occurred at wheels slip of 17% and 8% and at draft force of 22kN for 2WD and 4WD tractors respectively. The maximum value of P F increased as the tractor forward speed increased for both tractors but this maximum PF provided lower draft force which means the tractor can not pull wider implements or machines working at greater depths but at lower forward speed the situation is better. For lower forward speed (0.39 m/sec) the draft force at which the maximum PF occurred at is 29 kN and 34 kN for 2WD and 4WD respectively. When the forward speed increased to 1.20 m/sec the draft force decreased to 23kN and 28kN for 2WD and 4WD respectively. The results showed clearly that 4WD surpassed in performance 2WD. it is more efficiently in using the power at the traction wheels as draft force increased with less power losses through the wheels slip and the rolling resistance and that can be seen from the difference between Pd and PF. The power at the traction wheels (Pd), the weight of the tractor (Gt) and the tractor forward speed (Va) were connected in equation for 4WD and

Agricultural traffic: Motion resistance and soil compaction in relation to tractor design and different soil conditions

Farmers may desire a high cone index soil for tractive purposes or a low cone index (CI) soil for root penetration and seedling emergence. The function of any agricultural tractor is to provide mobility for itself and to power an implement. The aim of this paper was to (a) assess the impact of two tractors with different tyre sizes and axle loads on motion resistance (MR) and on the CI for three different soil mechanic conditions and (b) determine the existing relationships between MR and ground pressure parameters and tyre sinkage. Traffic was simulated with one pass on clay soil for a front-wheel assist tractor (FWA, load=77.7kN) and a four-wheel drive tractor (4WD, load=98.01kN) on three soil conditions: direct sowing systems, ploughed and seedbed. The outlined hypotheses were as follows: (1) there is a direct relationship between the subsoil compaction and the MR force of the FWA and 4WD tractors, and (2) the power loss produced by the MR depends on the soil mechanics. The experiment was conducted in the eastern section of the Rolling Pampa region of Argentina at 34°36′S, 58°40′W. MR, rut depth (RD) and CI were measured. The MR mean values of the 4WD were 9.30, 6.59 and 2.31kN for ploughed, seedbed and direct sowing soil, respectively, whereas the values for the FWA were 10.41, 7.91 and 4.67kN, respectively. For the three soil conditions, no significant differences were found in the RD between the 4WD and FWA. For the topsoil level (0–150mm), one FWA pass caused mean values in the CI of 2150, 1835 and 1780kPa for direct sowing, seedbed and ploughed soil, respectively, whereas for 4WD the values were 1890, 1640 and 1587kPa, respectively. For the subsoil (150–600mm), 4WD caused higher CI values than the FWA. The CI mean values of the 4WD were 2477, 2240 and 1890kPa for direct sowing, seedbed and ploughed soil, respectively, whereas the values for the FWA were 2240, 1870 and 1770kPa, respectively. For the different soil conditions, the subsoil compaction increased as the total axle load increased, independently from the ground pressure. Moreover, for both tractors, a greater MR force was observed in the soil with the lowest bearing capacity. The smallest power loss ratio due to MR and engine power was found with the 4WD.

차축의 중량 분포와 타이어의 공기압이 트랙터 작업의 연료 효율에 미치는 영향

, 2011)This study was conducted to investigate the effects of axle weight distribution and inflation pressure of tire on the fuel economy of tractors as well as operational range of tractor engine in terms of engine speed and power when a 4WD tractor of 38.2 kW rated power at 2500 rpm is used for plowing and flooded-field rotavating in paddy fields. (1) Plowing operation required an average engine power of 9.6~13.5 kW which equals 25~35% of rated PTO power. Engine speed ranged from 1,320.4 to 1,737.4 rpm, work velocity from 3.4 to 4.8 km/h, and fuel consumption from 3.2 to 4.2 L/h, respectively.(2) Flooded-field rotavating required an average engine power of 11.5~18.5 kW which equals 30~48.4% of rated PTO power. Out of this 6.2~12.2 kW was used for PTO power. Engine speed ranged from 1,557 to 2,067 rpm, work velocity from 2.5~5.4 km/h and fuel consumption from 3.2~5.5 L/h, respectively.(3) Axle weight distribution, inflation pressure of tire and moisture content of soil did not affect significantly the specific volumetric fuel consumption but affected significantly the fuel consumption per unit area of operation. Fuel savings amounted to 65% in plowing operation and 20% in flooded-field rotavating when the axle weight distribution and inflation pressure of tire were optimally adjusted.(4) Optimal adjustment of axle weight distribution and inflation pressure of tire are expected to save fuel consumption by 10~65% per unit area of operation in plowing and 10~20% in flooded-field rotavating.

A simulation model of 2WD tractor performance

The aim of this study was to develop a model that can accurately simulate the performance of a 2WD tractor with a suspended working implement (cultivator) on various types of soil. The following performance indicators were assessed with the use of the developed model: tractor's overall efficiency, tractive efficiency, specific fuel consumption and soil productivity. The proposed model supports the determination of performance indicators accounting for the overall loss of energy during machine operation. Overall efficiency is such an indicator. The value of this parameter varies significantly subject to changes in tractive force from 0 to 7 kN for the analyzed values of the fuel injector control signal and the total transmission ratio in the third (3L), fourth (4L) and fifth (1H) gear. For this reason, the above indicator may be used to determine the optimal parameters of tractor performance. The above variability was not reported in respect of the coefficient of tractive efficiency.

Verifying Power Claims of High-Power Agricultural Tractors Without a PTO to Sell in Nebraska

Nebraska law requires the Nebraska Tractor Test Board of Engineers to compare results of the tests of an agricultural tractor model with the manufacturer's claims regarding power, fuel use, and other performance ratings in order to recommend a permit to sell that tractor model in the state. PTO tests are conducted to verify the manufacturer's PTO power and fuel claims for tractor models. In recent years, several tractor manufacturers have been producing models of large tractors either without a PTO or with a PTO not capable of transmitting the full engine power and, therefore, have chosen to advertise engine power. The objective of this project was to determine a reasonable alternative to removing engines from these tractors for tests to determine whether these tractors met their power claims. Linear regression analyses of advertised engine power claims and OECD Code 2 drawbar power test results from 48 tracked (R2 = 0.98) and 43 4WD tractors (R2 = 0.99) were used to establish two linear relationships to verify the engine power claims for these tractors. These relationships provide a reasonable means of verifying engine power claims for large agricultural tractors without a PTO, or without a PTO capable of transmitting full engine power.

Digital wheel slipmeter for agricultural 2WD tractors

A microcontroller based digital slipmeter was developed for agricultural two wheel drive (2WD) tractors. The actual and theoretical speeds of tractor were calculated by measuring the revolutions per minute (RPM) of front wheel and rear wheels, respectively, using optical slot sensors. A microcontroller was programmed to calculate the actual forward speed and wheel slip of the tractor. These measured values were digitally displayed on the tractor dashboard. The slipmeter was fabricated in such a way that it could be mounted on any make and model of 2WD tractor. The slipmeter was rigorously tested in the laboratory as well as in the field with different tractor–implement combinations. A maximum of ±2 per cent variation was observed between measured and indicated wheel slip.

Soil compaction distribution under tractor traffic in almond ( Prunus amigdalus L.) orchard in Almería España

Almond orchards in Almería require frequent traffic with farm machinery, about 1–8 times a year. Our main objective was to evaluate the vertical distribution of soil compaction induced by traffic of two tractors with different weights, one light (LT = 15 kN) and one heavy (HT = 50 kN), passing 0, 1, 3, 5 and 8 times over the same track on Aridisol soil. The work was performed in the Vélez Blanco District of Almería in southeast Spain. Outlined hypothesis were: (a) subsoil compaction distribution due to tractor traffic on recently tilled soils in almond orchard depends on total axle load and tractor passes, (b) topsoil compaction produced by tractor traffic depends on tractor passes and ground pressure. Variables measured were (CI) cone index, (BD) bulk density, (TSP) total soil porosity and (RD) rut depth. The relevant results were: in topsoil (0–200 mm), 1, 3, 5 and 8 passes of a LT caused mean values of CI of 1420, 1825, 1950 and 2050 kPa respectively, while for the HT with the same number of passes the values were of 1235, 1520, 1630 and 2510 kPa respectively. BD mean values had a similar behavior: 1.35, 1.38, 1.51 and 1.55 Mg m −3 for 1, 3, 5 and 8 passes of a LT and 1.30, 1.32, 1.41 and 1.52 for the HT with the same number of passes. In the subsoil (200–600 mm) the HT caused higher CI and BD values than the LT. CI mean values of the LT were between 1705 and 2490 kPa, while the HT produced 2100–2790 kPa of CI. BD mean values were between 1.58 and 1.7 Mg m −3 for the LT and 1.65–1.77 Mg m −3 for the HT. Hence, the data support both hypotheses. No significant differences were found in RD between HT and LT when they passed 1, 3 or 5 times, but there was a difference when traffic raised up to 8 passes (143 mm RD for HT). The main conclusions were: (a) this work has shown that soil compaction resulting from tractor traffic increases CI and BD and decreases total soil porosity. The data of CI and BD indicated that Almond orchard soil is unable to limit subsoil compaction under moderate traffic intensity. (b) Up to the fifth pass of either a FWA or 2WD tractor, ground pressure is responsible for topsoil compaction.

A program in Visual Basic for predicting haulage and field performance of 2WD tractors

A tractor drawbar performance program that predicts the performance of two-wheel-drive (2WD) tractors for haulage as well as field operations for both bias-ply and radial-ply tyres is developed to meet user requirements in educational and research organizations. The program is written in Visual Basic programming language. The program provides an intuitive user interface by linking databases such as tractor specifications, tyre data, implement and trailer specifications and traction equation coefficients to predict the performance of a selected tractor model. The program has been proven to be user friendly and efficient for various field operations under frictional–cohesive soils.

Soil compaction produced by tractor with radial and cross-ply tyres in two tillage regimes

The aim of this paper was to quantify soil compaction induced by tractor traffic on two tillage regimes: conventional tillage and direct drilling. Traffic was simulated with one pass of a conventional 2WD tractor, using four configurations of cross-ply rear tyres: 18.4–34, 23.1–30, 18.4–38 and 24.5–32, and four configurations of radial tyres 18.4R34, 23.1R 30, 18.4R 38 and 24.5R 32, with two ballast conditions used in each configuration. The experiment was conducted in the east of the Rolling Pampa region, Buenos Aires State, Argentina at 34°25′S, 59°15′W; altitude 22 m above sea level. Rut depth after traffic and soil bulk density and cone index in a 0–450-mm profile were measured before and after traffic. Considering topsoil level, in two tillage regimes, all treatments induced significant values of soil compaction as compared to the control plot without traffic. Subsoil compaction increased as total axle load increased and was independent of ground pressure. For the same tyre configuration, radial tyre caused less soil compaction than the cross-ply.

Experimental analysis of vertical soil reaction and soil stress distribution under off-road tires

In this study, the vertical soil reaction acting on a driven wheel was measured by strain gages bonded to the left rear axle of a 2WD tractor driven under steady-state condition on different soil surfaces, tractor operations, and combinations of static wheel load and tire inflation pressure. In addition, the measurements of radial and tangential stresses on the soil–tire interface were made simultaneously at lug’s face and leading side near the centerline of the left rear tire using spot pressure sensors. The experimental results indicate that the proposed method of vertical soil reaction measurement is capable of monitoring the real-time vertical wheel load of a moving vehicle and provides a tool for further studies on vehicle dynamics and dynamic wheel–soil interaction. Furthermore, the measured distributions of soil stresses under tractor tire could provide more real insight into the soil–wheel interactions.

Comparative Analyses of the 4WD Tractor Performance with Two Different Mouldboard Plow Bottoms by Using FEM

Silindirik formda bir kulaklı pulluk model ve tasarımı için teorik bir çalışma yapılmıştır. Bu çalışmada dizayn edilen pulluk ile tip 113 pulluğunun performansları iki farklı toprak derinliğinde 15-20 ve 20-25 cm ve üç farklı hız kademesinde 4.4, 6,9 km/h karşılaştırmalı olarak yapılmıştır. Çalışmada ele alınan dizayn parametreleri; çeki kuvveti, von misses stresi, eğilme momenti sonlu elemanlar yöntemi FEM ile analiz edilmiştir. Ele alınan bazı toprak göstergeleri; pulluk izi, eğim derecesi, pulluk yüzey ve açısıdır. Tesadüfi deneme blokları kullanılarak elde edilen veriler istatistiksel olarak analiz edilmiştir. Dizayn edilen kulaklı pulluğun tüm dizayn göstergelerinde çeki kuvveti, von misses stresi ve eğilme momenti bakımından, 113 tip pulluktan daha az olmak suretiyle daha iyi performans gösterdiği bulunmuştur. Sonuçlar, ilerleme hızı arttıkça çeki kuvveti, von misses stresi ve eğilme momentinin arttığını göstermiştir. Aynı şekilde artan toprak işleme derinliklerinde çeki kuvveti, von misses stresi ve eğilme momentinin de arttığı görülmüştür. En iyi performans ise 15-20 cm toprak derinliğinde 9 km/h ilerleme hızında elde edilmiştir

A decision support system on matching and field performance prediction of tractor-implement system

A decision support system (DSS) was developed in Visual Basic 6.0 programming language for matching tillage implements with 2WD tractors and for predicting the field performance of the tractor-implement system. The DSS provides the intuitive user interfaces by linking databases such as tractor, tire and implement specifications, draft and traction models constants, soil and operating conditions to support the decision on matching and to predict the performance of a selected tractor-implement system. The DSS was validated with the data collected from the field experiments conducted with a 31 kW PTO power 2WD tractor and three tillage implements (2–30 cm moldboard plow, 7-7 disks (1.6 m) offset-disk harrow and 9–23 cm field cultivator) under different soil and operating conditions. It was found that the DSS on an average under-predicted the draft and slip values by 10.2 and 15.6%, respectively, while it over-predicted the actual field capacity by 2.5% from the observed values. It was found that a 20 kW tractor was properly loaded with 2–30 cm moldboard plow but was overloaded with 9–23 cm field cultivator for the normal operating conditions in medium soil. However, a 31 kW tractor was found to be underloaded while working with these implements in medium soil.

Wheel slip measurement in 2WD tractor

A microcontroller-based slip sensor was developed for a 2WD tractor to indicate slip values during on-farm use. The ‘zero condition’ considered for the development of slip sensor was – tractor supplied with a driving torque to propel any device across a tarmacadam surface while delivering zero net traction (self-propelled condition). This sensor comprised of four components: power supply; sensing of throttle position, gear position, and wheel rpm; processing of collected data; and display unit. Power was taken from the tractor battery. Rotary potentiometer and proximity switches were installed on the tractor to measure throttle position and wheel revolution, respectively. The performance of developed slip sensor was evaluated both on tarmacadam surface as well as in the field. The variations between indicated and actual slip were found to be within 0–5% for both the surfaces, thus indicating the accuracy of slip measurement by the developed slip sensor.