• Journal of Biosystems Engineering
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• v.37 no.3
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• pp.131-139
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• 2012

In this study, we developed a simulation program for the prediction of tractive performance of a tractor, by applying a widely used empirical model for tractive performance prediction of single tire, Brixius. The tractive performance prediction program can readily predict and estimate tractive performance according to various soil conditions and different specifications of tractors. The program was developed with the considerations of tractor's specification-related parameters (e.g., weight, tire size, and wheelbase of the tractor), a soil parameter (i.e., cone index which represents the soil strength), and operating conditions of the tractor (e.g., theoretical speed and driving types such as 2WD and 4WD). Also, the program was designed to provide tractive performance prediction results of tractors such as gross traction, motion resistance, net traction, and tractive efficiency, in the form of not only numerical values but also graphical visualization. To evaluate the feasibility of the program, we input three different soil conditions (which have different cone indexes each other) and tractor operating conditions to the program and analyzed the tractive performance from each input condition. From the analysis, it can be concluded that the developed program can be effectively utilized to predict the tractive performance under various soil conditions and driving types of tractors with different specifications.

• Transactions of the Korean Society of Automotive Engineers
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• v.5 no.2
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• pp.1-12
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• 1997

A computer program was developed to simulate effect of the initial track tension on the tractive performance of tracked vehicles. The performance was evaluated in terms of drawbar pull, motion resistance, tractive coefficient and tractive efficiency. Results of the simulation showed that increase in track tension decreases the sinkage and mean maximum pressure in clay, making the ground pressure distribution more uniform. This tendency became more evident when the number of roadwheels increased. However, such change in MMPs was negligible in firm soils. Motion resistance was also decreased with increase in track tension and the number of roadwheels. Under weak soil conditions, tractive coefficient and efficiency increased generally as the track tension increased for a slip range of 10∼30%. For slippage less than 3∼4%, however, the tractive coefficient decreased with increase in track tension. In general, it was known that increasing track tension improves tractive performance in weak soil conditions. However, high track tension can reduce efficiency due to the increment of internal motion resistance caused by increased track tension.

• Journal of Biosystems Engineering
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• v.27 no.6
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• pp.491-500
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• 2002

This study was carried out to investigate experimentally the effect of the tire inflation pressure of a tractor on soil compaction and tractive performance. Two kinds of field experiments were conducted using an agricultural tractor. One experiment is concerned with the tractive performance of the tractor at the three levels of tire inflation pressure; 50kpa, 100kpa and 200kpa, and the other one is about the soil compaction at the four levels of tire inflation pressure; 50kpa, 100kpa, 150kpa and 200kpa, at three different numbers of passes; 1, 3 and 5 passes. From the results of the field experiment, it was found that decreasing the tire inflation pressure decreased the motion resistance of tractor and increased the tractive force and tractive efficiency. The tractive and working performance of the tractor could be improved by the reduction of tire inflation pressure. Increasing the inflation pressure and the number of passes increased the soil compaction. Rate of compaction increased rapidly at the first pass and declined at subsequent passes. To reduce the effect of soil compaction for the whole field, it is recommended that tractor should follow the rut of the first pass from the subsequent passes, and decrease the inflation pressure of the driving tires up to allowable minimum level.

• Journal of Biosystems Engineering
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• v.24 no.2
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• pp.89-98
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• 1999

In this paper, to estimate the effectiveness of the tractive performance prediction model(TPPMTV98) which was developed to predict the tractive performance of flexible tracked vehicles in previous paper, the experimental substantiation of the TPPMTV98 were conducted with the reconstructed tracked vehicle on the loam soil with the moisture content of 18.92%, and bevameter was constructed in order to measure soil properties in situ. The drawbar pulls measure were compared with predicted ones. As a result, the predicted drawbar pulls by the TPPMTV98 were well matched to the measured ones. Such results implied that the TPPMTV98 could well estimate the drawbar pulls at given soil conditions, and would be very useful as a simulation tool for designing a flexible tracked vehicle and predicting its tractive performance.

• Transactions of the Korean Society of Automotive Engineers
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• v.10 no.1
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• pp.234-243
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• 2002

When a vehicle is operated over sort terrain, torque(or soil thrust) applied to driving wheel brings about shear displacement far soil due to compression and shear failure of soil under tire. This shear displacement give rise to slip and a additional sinkage due to slip. This additional sinkage is usually referred to as slip-sinkage. The slip-sinkage is affected by soil conditions and inflation pressure of tire. This slip-sinkage influence tractive performance on driving wheel . We conducted the experimental study far investigating the effect of slip on sinkage and tractive performance of driving wheel, such as motion resistance, thrust and drawbar pull. The experiment was carried out over three different soil conditions(soft, hard and very hard soil) far a tire with three levels of inflation pressure(120kPa, 240kPa and 360kPa). The results of this study show qualitatively slipsinkage characteristics and slip-tractive performance relationships of driving wheel with soil conditions and inflation pressure of tire.

• Journal of Biosystems Engineering
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• v.23 no.1
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• pp.1-12
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• 1998

This study was intended to investigate experimentally the effect of inflation pressure on tractive performance of bias-ply tires for agricultural tractors. Traction tests were conducted at the three velocities of 3, 4, and 5.5km/h under few different surface conditions using a 13.6-28 6PR bias-ply tire as driving wheel of the test tractor. When the inflation pressure was reduced from 250kPa to 40kPa by a decrement of either 30 or 50kPa depending upon the test surface conditions, some of the test results showed that the tractive coefficient and efficiency were increased maximally by 40% and 17％, respectively, at 20% slippage. However, it was failed to derive any consistent rules depicting the effect of inflation pressure of bias ply tires on the tractive performance of tractors.

• Journal of Biosystems Engineering
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• v.23 no.3
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• pp.219-228
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• 1998

This study was conducted to develop the mathematical model and computer simulation program(TPPMTV98) for predicting the tractive performance of tracked vehicles. It takes into account major design parameters of the vehicle as well as the pressure-sinkage and shearing characteristics of the soil, and the response of the soil to repetitive loading. Structural analysis and numerical iterative method were used for the derivation of mathematical model. The simulatiom model TPPMTV98 can predict the ground pressure distribution and the shear stress under a track, the motion resistance, the tractive effort and the drawbar pull of the vehicles as functions of slip. Predicted tractive performance results obtained by the simulation model were validated by comparing the results firm the Wong's model, the offectiveness of Wong's model validated by many of the experiment. It was found that there is fairy close agreement between the prediction by TPPMTV98 and the results from Wong's model. The computer simulation model TPPMTV98 can be used for the optimization of tracked vehicle design or for the evaluation of vehicle candidates for a given mission and environment.

• Journal of Biosystems Engineering
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• v.25 no.2
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• pp.79-88
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• 2000

Effects on tractive performance of design parameters of cage wheel as a traction aid to driving tires of tractor in wet paddy field were investigated experimentally. an experimental cage wheel was designed so that the design parameters such as wheel diameter, wheel width, lug pitch and lug angle could be varied during traction test, The traction test was conducted in two different types of wet paddy field ; shallow and deep harpan fields . Experimental results showed that tractive performance is affected by both soil conditions and the design parameters. A considerable improvement on the tractive performance was obtained by using a cage wheel with 45$^{\circ}$ lug angle in shallow hardpan and smaller lug pitch in deep hardpan. The diameter of cage wheel was mostly influential to the tractive performance both in shallow and deep hardpans.

• Agricultural and Biosystems Engineering
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• v.4 no.1
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• pp.34-38
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• 2003

A mathematical model was developed for estimating the mechanical interrelation between characteristics of soil and main design factors of a tracked vehicle, and predicting the tractive performance of the tracked vehicle. Based on the mathematical model, a computer simulation program (TPPMTV) was developed in the study. The model considered the continuous change in tension for the whole track of a tracked vehicle, the analysis of shape and tension of the track segment between sprocket and first roadwheel, and the side thrust on both sides of grouser by the active earth pressure theory in predicting the tractive performance of a tracked vehicle. Also, the model contained not only sinkage depth of the track but the pressure distribution under the track in analyzing the side thrust. The effectiveness of the developed model was verified by performing the draw bar pull tests with a tracked vehicle reconstructed for test in loam soil with moisture content of 18.92％. The predicted drawbar pulls by the model were well matched to the measured ones. Such results implied that the model developed in the study could estimate the drawbar pulls well at various soil conditions, and would be very useful as a simulation tool for designing a tracked vehicle and predicting its tractive performance.

• Transactions of the Korean Society of Automotive Engineers
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• v.7 no.6
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• pp.248-257
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• 1999

A mathematical model was developed to investigate the mechanical interrelation between soil characteristics and main design factors of a tracked vehicles , and predict the tractive performance of the tracked vehicles. Based on the mathematical model, a computer simulation program(TPPMTV98) was developed in this study. The effectiveness of the developed model was verified by comparing the predicted drawbar pulls using TPPMTV98 with measured ones from traction tests with a tracked vehicle reconstructed for test in loam soil with moisture content of 18.92%(d.b). The drawbar pulls measured by the TPPMTV98 were well matched to the measured ones. Such results implied that the model developed in this study could estimate the drawbar pulls well at various soil conditions , and would be very useful as a simulation tool for designing a tracked vehicle and predicting its tractive performance.