Bias-ply Tires Research Articles

Agricultural Tire Test: Straw Cover Effect on Reducing Soil Compaction by Cargo Vehicles

Agricultural cargo vehicles are responsible for applying severe soil pressures. However, the ground straw cover can attenuate the loads applied by wheels to the soil surface. This research evaluated the effect of three tires, p1—Radial Very Flex, p2—Radial Improved Flex, and a p3—Bias Ply tire, on three amounts of straw on the soil surface (0, 15, and 30 Mg ha−1). We adopted a completely randomized design (CRD) with a rigid surface for three replications for the total contact area and punctual area claws. The soil bin test verified the deformable surface, tread marks, and soil penetration resistance (SPR). The tire’s claw design determines its punctual contact area, and the construction model determines the total contact area. The contact area in the soil bin increased linearly due to a increase in straw covering, reducing sinkage; p2 to 30 Mg ha−1 straw shows the most significant contact area, p1 and p3 showed no difference. A straw increase from 0 to 30 Mg ha−1 increased the contact areas by 25.5, 38.0, and 20.0% for p1, p2, and p3, respectively. Compared to the rigid surface, the p1 and p3 contact areas in the soil bin increased 6.2, 6.8, and 7.8 times in bare soil, 15, and 30 Mg ha−1; for p2, this increase was up to 4.2, 4.5, and 5.9 times on the same surfaces. Keeping the straw on the soil improves its physical quality by reducing the SPR, so the straw has a buffer function in the wheel–soil relationship.

Evaluation of the Changes in Dimensions of the Footprint of Agricultural Tires under Various Exploitation Conditions

This paper presents an innovative method to determine the impact of agricultural wheels on soil. The experiment was conducted under controlled conditions, and the parameters of the tire footprints on the soil were analyzed. The tested parameters were the width, length, and depth of the footprint, the cross-section area of the tire, and the area of the footprint. All parameters were determined using the 3D scanning method. Two types of tires, two levels of vertical load, and three levels of inflation pressure were used. The aim of the research was to demonstrate differences in changes in the footprint parameters as a result of changes in the operational parameters of the tires. It was found the bias-ply tire was less responsive to changes in the width and length of the footprint than the radial tire. Moreover, it was shown that radial and bias-ply tires achieved similar values for the footprint area but in the case of bias-ply tires, there was a much greater footprint depth. This means that the side parts of the footprint of bias-ply tires have a more vertical profile, so they carry the vertical loads to a lesser extent.

Validation of an electro-hydraulic press for dynamic measurement of elastic deformations in agricultural tires

Tests with agricultural tires and wheelsets allow for mitigating the machinery traffic limitations to crop productivity, as it shows the tire-surface interaction under different suitability conditions, optimizing farming processes with the use of technology. Thus, this paper aims to develop an electro-hydraulic press for dynamically measuring elastic deformations occurring in agricultural tires. The experiment used a completely randomized design, evaluating two pneumatic wheelsets, bias-ply and radial, and six vertical loads, 4.9033, 9.8066, 14.71, 19.6133, 24.5166, and 29.4199 kN, on the tire, totalizing 12 treatments with five repetitions. The analyzed parameters are contact area, horizontal and vertical deflection. The collected data underwent an analysis of variance F-test and a polynomial regression analysis. The results showed continuous replicability of the data obtained with the electro-hydraulic press. That demonstrates the efficiency of the developed device for evaluating agricultural tires in a controlled environment. The bias-ply tire presented a smaller contact area than the radial with the increase of incident loads, and the 14.71 kN load achieved a higher amplitude, generating a difference of 40 %. The maximum load resulted in 27 % more horizontal deflections for the radial tire. However, the vertical deflection values were 8 % higher with the bias-ply tires.

Measurement and Analysis of the Influence Factors of Tractor Tire Contact Area Based on a Multiple Linear Regression Equation

Tractor tire three-dimensional (3D) contact area is one of the significant concerns of the soil-tire coupling mechanism, and it influence soil compaction and the sustainable development of agriculture. In this study, we developed a method to measure the 3D contact area of a pneumatic tire using a laser profiler on a signal tire soil-bin testing facility. A 6.00-14 bias-ply tire with high lugs was driven on sandy loam soil in a soil-bin testing facility under different vertical loads, driving speeds, and inflation pressures. Then, we developed a multiple linear regression equation between the influence factors and tractor tire contact area. The results indicated that the contact area was impacted by the three factors involved in this study, and the inflation pressure significantly influenced results, and the combination of high speed (3 m/s), low inflation pressure (69 kPa), and high tire load (2.5 kN) led to a relatively high contact area on the soil-tire contact interface and possible severe soil compaction. Also, we found that the contact area varied in a quadratic manner with speed at a given inflation pressure and tire load and varied in a quadratic manner with inflation pressure at a given speed and tire load and varied linearly with the tire load for a given speed and inflation pressure.

Evaluation of Tires Acting on Soil in Field Conditions Using the 3D Scanning Method

This research presents the results of tests conducted under field conditions and included measuring the footprint of tires on soil. Two agricultural tires of the same size but different internal structures were tested, 500/50R17 (radial) and 500/50-17 (bias-ply). The factors were tire inflation pressure (0.8 bar, 1.6 bar, and 2.4 bar) and tire vertical load (7.8 kN, 11.8 kN, and 15.7 kN). The footprint made on the soil was scanned with a 3D scanner, resulting in a digital image of the tire footprint on the soil to enable an analysis of the measured parameters: length, width, depth, and contact area (in 3D form). Statistical analysis showed that for radial tire footprints, both inflation pressure and vertical load had a significant effect on all analyzed parameters. For bias-ply tire footprints, it was shown that only inflation pressure had a significant effect on all of the analyzed parameters, while the significance of the effect of the vertical load was not confirmed for the footprint depth. Based on the results obtained, the suitability of models describing the relationship between operating factors and the actual footprint area was verified. It was found that for a radial tire, the model formulated based on laboratory tests can predict the contact surface under field conditions (the correlation coefficient R2 was equal to 0.9226). In the case of a bias-ply tire, the correlation coefficient R2 reached a value equal to 0.5828. This indicates a less accurate estimation of the surface area under field conditions based on the model designed after laboratory testing.

Evaluation of Tire Footprint in Soil Using an Innovative 3D Scanning Method

This paper presents the results of the measurement of tire footprints in soil. The research was conducted under laboratory conditions using soil-filled cases. The research objects were two tires: a radial tire and a bias-ply tire of the same size. The variable parameters were vertical load (7.8 kN, 15.7 kN, 23.5 kN) and inflation pressure (0.8 bar, 1.6 bar, 2.4 bar). Test benches with a mounted tire, a soil case, and a 3D scanner were used in the research. Using the test bench, a tire was loaded with each inflation pressure, and a tire footprint was generated in the soil. Then, a 3D scanner was used to scan the tire footprint, and the parameters of length, width, depth, and tire–soil contact area (as a spatial image) were evaluated using special software. Then, mathematical models were formulated (separately for each type of tire) to describe the tire–soil contact area of the tire footprint as a function of the vertical load and inflation pressure. It was found that the depth of the tire footprint is an important parameter that influences the tire–soil contact area value. However, it was also found that with the right combination of inflation pressure and vertical load, a longer and wider, but shallower, tire footprint can be generated, the contact area value of which is similar to that of a deeper footprint.

Effects of Some Properties of Drive Tires Used in Horticultural Tractors on Tractive Performance

Many studies on tractive performance of tractor tires have been carried out to solve soil-wheel interaction problems in the last decades. The purpose of this study is to experimentally determine effects on tractive performance of radial and bias-ply drive tires at three different tire lug heights, axle loads and inflation pressures. The experiments were carried out in stubble field conditions. To obtain sufficient performance data, a new single wheel tester was designed and manufactured. Travel reduction, net traction ratio and tractive efficiency varied from 3.3% to 34.1%, 0.24 to 0.93 and from 0.27 to 0.78 respectively depending on drawbar pull. The effects of tire type, lug height, dynamic axle load and inflation pressure on tractive efficiency were found significant (P<0.01) by the performed variance analysis and LSD tests. Radial tires provide better tractive performance compared with bias-ply tires. The tractive efficiency increased especially with increasing dynamic axle load and decreased with increasing tire inflation pressure. Tire dynamic axle load was the major contributory factor on tractive performance as compared with other independent variables. For a given drawbar pull, it was observed that tractive efficiency of radial tire can be maximized by selecting appropriate levels of lug height, dynamic axle load and inflation pressure.

Computer simulation for predicting tractor engine overloading for tillage operations

The primary purpose of agricultural tractors, especially those in the middle to high power range, is to perform field work. Tractor manufacturer needs prediction of tractor field performance data in the tractor design stage itself so that they can optimize the transmission with the engine to give better performance. Engine speed prediction model was developed using Budni tractor test data. Developed engine speed prediction model for 10 engine model was compared with actual data of engine speed, it was found that for all engine models R 2 (co-efficient of determination) between predicted and actual engine speed was greater than 0.98. So developed empirical equations can be used in software for predicting engine speed. The field experiments were conducted using a tractor with three different implements viz., 3-bottom mould board plough, 11-tyne cultivator and offset disc harrow. For each operation, the performance parameters such as draft, slip, depth, engine speed and fuel consumption were measured at different combinations of gear and throttle positions. Software in visual basic was developed to predict tractor engine overloading (engine speed drop) for field operations (MB plough, cultivator and disc harrow). The developed software was validated using field data collected in Kanchipuram, Tamil Nadu. For field operation with 2 WD tractor equipped with bias-ply tires and attached with cultivator the deviation of software predicted engine speed (rpm) drop was -16.47 to 26.92 per cent and for draft was -11.07 to 4.65 per cent. For field test with offset disc harrow the deviation of software predicted engine speed (rpm) drop was -17.44 to 15.38 per cent and for draft was -10.98 to 4.76 per cent. For field operation with MB Plough the deviation of software predicted engine speed (rpm) drop was 18.48 to 21.52 per cent and for draft -12.01 to -3.75 per cent.

A Novel Technique to Measure the Rolling Resistance of Tyres Using Force Transducer

A novel laboratory technique has been used to measure the rolling resistance of tyres using a force transducer. The effect of inflation pressure, normal load and speed has been studied for two different bias-ply tyres—with and without treads. As anticipated, the results indicate that a treaded tyre has higher value of the rolling resistance as compared with a tyre with treads removed.

Equilibrium Profile of Modern Belted Radial Ply Tires: Its Determination and Performance Benefits

ABSTRACT The benefits of a tire's equilibrium profile have been suggested by several authors in the published literature, and mathematical procedures were developed that represented well the behavior of bias ply tires. However, for modern belted radial ply tires, and particularly those with a lower aspect ratio, the tire constructions are much more complicated and pose new problems for a mathematical analysis. Solutions to these problems are presented in this paper, and for a modern radial touring tire the equilibrium profile was calculated together with the mold profile to produce such tires. Some construction modifications were then applied to these tires to render their profiles “nonequilibrium.” Finite element methods were used to analyze for stress concentrations and deformations within all tires that did or did not conform to equilibrium profiles. Finally, tires were built and tested to verify the predictions of these analyses. From the analysis of internal stresses and deformations on inflation and loading and from the actual tire tests, the superior durability of tires with an equilibrium profile was established, and hence it is concluded that an equilibrium profile is a beneficial property of modern belted radial ply tires.

Rolling resistance and rut formation by implement tyres on tilled clay soil

The rolling resistance and rutting incurred by towed flotation implement tyres were investigated on an arable clay soil in three different soil strength conditions. Three radial (600/55R26.5) and two bias ply (600/55–26.5) tyres were compared. Experimental wheel loads were in the 35.4–36.4 kN range. Tyre inflation pressures, representing typical field operation, and road transport applications were in 100–150 kPa and 150–200 kPa, respectively. Soil strength was determined from mean soil penetration resistance (CI 0–15, in the layer 0–15 cm) and mean cohesion ( C 0–10, 0–10 cm). Wheel rolling resistance evaluated by the coefficient of rolling resistance (CRR), rut depth (RD), driving speed, and field gradient were measured with the tyres mounted on a test trailer hitched to a tractor. CI 0–15 and C 0–10 values predicted the sinkage and the resistance to travel motion on clay soil reasonably well. When the CI 0–15 was less than 1 MPa and C 0–10 was below 100 kPa, CRR and RD increased rapidly. On average, CRR was 20% lower for the radials than the bias plies. In soft conditions (CI 0–15 ⩽ 0.48 MPa), the radials produced 15% shallower ruts than bias plies, and the CRR was lower and RD shallower with field inflation pressures than with road pressures used. According to our results, flotation tyres can be recommended to agricultural machines when the implement or trailer is used in soft soil conditions.

최대 견인 출력시 트랙터 엔진의 견인 부하 분석

This study was conducted to investigate the load acting on a tractor engine when it delivers the maximum power at drawbar. The results of the drawbar tests on the 5 locally-made and 14 imported tractors conducted at NIAE in 2004, and the 15 tractors tested at OECD test stations in foreign countries were analyzed and presented by the torque load ratio, defined as a ratio of the engine torque load caused by drawbar pull to its full-load capacity, as a function of pull speed. The NIAE test results showed that the torque load ratio increased from 20 to 80% with pull speed less than 5 km/h. At speeds faster than 5 km/h, it was 80<TEX>${\sim}$</TEX>110% regardless of the pull speed. However, the OECD test results showed that the torque load ratio was evaluated mostly to be 70<TEX>${\sim}$</TEX>90% in the entire pull speed range. The same trend was also shown for the maximum drawbar load. The difference in the torque load ratio may be attributable to bias-ply tires for locally-made and some imported tractors. It is also suggested that the input torque load may be increased safely up to 120% of the full load capacity of the tractor engine for an accelerated life test of tractor transmissions.

An empirical model for tractive performance of rubber-tracks in agricultural soils

Mathematical models capable of describing the interaction between traction devices and soils have been effective in predicting the performance of off-road vehicles. Such a model capable of predicting the performance of bias-ply tires in agricultural soils was first developed by Brixius [Brixius WW. Traction prediction equations for bias-ply tires. ASAE Paper No. 871622. St. Joseph, MI: ASAE; 1987]. When the soil and vehicle parameters are known, this model uses an iterative procedure to predict the tractive performance of a vehicle including pull, tractive efficiency, and motion resistance. Al-Hamad et al. [Al-Hamad SA, Grisso RD, Zoz FM, Von Bargen K. Tractor performance spreadsheet for radial tires. Comput Electron Agr 1994:10(1):45–62] modified the Brixius equations to predict the performance of radial tires. Zoz and Grisso [Zoz, FM, Grisso RD. Traction and tractor performance. ASAE Distinguished Lecture Series #27. St. Joseph, MI: ASAE; 2003] have demonstrated that the use of spreadsheet templates is more efficient than the original iterative procedure used to predict the performance of 2WD and 4WD/MFWD tractors. As tractors equipped with rubber-tracks are becoming popular, it is important that we have the capability to predict the performance for off-road vehicles equipped with rubber-tracks during agricultural operations. This paper discusses the development of an empirical model to accomplish this goal and its validity by comparing the predicted results with published experimental results.

Influence of the axle load, tyre size and configuration on the compaction of a freshly tilled clayey soil

Enhancement of the potential root growth volume is the main objective of farmers when they establish a conventional tillage system. Therefore, the main function of primary tillage is to increase soil’s structural macroporosity. In spite of this, during secondary tillage operations on these freshly tilled soils, the traffic on seedbeds causes significant increases in soil compaction. The aim of this paper was to quantify soil compaction induced by tractor traffic on a recently tilled non consolidated soil, to match ballast and tyre size on the tractors used during secondary tillage. The work was performed in the South of the Rolling Pampa region, Argentina. Secondary tillage traffic was simulated by one pass of a conventional 2WD tractor, using four configurations of bias-ply rear tyres: 18.4×34, 23.1×30, 18.4×38 and 18.4×38 duals, two ballast conditions were used in each configuration. Soil bulk density and cone index in a 0 to 600 mm profile were measured before and after traffic. Topsoil compaction increased as did ground pressure. Subsoil compaction increased as total axle load increased and was independent from ground pressure. At heavy conditions, topsoil levels always showed higher cone index values. From 150 to 450 mm depth, the same tendency was found, but with smaller increases in the cone index parameter, 22 to 48%, averaging 35%. Finally, at the deepest layer considered, 600 mm, differential increases due to the axle load are great enough as to be considered similar to those found in the upper horizon, 36 to 64%, averaging 55%. On the other hand, bulk density tended to be less responsive than cone index to the traffic treatments. Topsoil compaction can be reduced by matching conventional bias-ply tyres with an optimized axle weight.

Technical Note: Rolling dynamic stiffness and damping characteristics of small-sized pneumatic tyres

In this paper, a laboratory technique for determination of rolling dynamic stiffness and damping coefficients of small-sized, bias-ply tyres has been discussed. The effect of normal load, inflation pressure and speed on four different tyres has been reported. The results show similar trends to those reported by other investigators.

Effect of inflation pressure on tractive performance of bias-ply tires

This study was to investigate the effect of inflation pressure on the tractive performance of bias-ply tires for agricultural tractors. Traction tests were conducted at velocities of 3, 4, and 5.5 km h −1 under four different surface conditions using a 13.6–28 6PR bias-ply tire as driving the wheel of the test tractor. When the inflation pressure was reduced from 250 to 40 kPa by a decrement of either 30 or 50 kPa depending upon the test surfaces, some of the test results showed that the traction coefficient and tractive efficiency were increased maximally by 14 and 6%, respectively, at 20% slip. However, such improvements in traction were not statistically consistent enough to find any rules regarding the effect of inflation pressure of bias ply tires on the tractive performance of tractors.

Effects of road transport on indices of stress in horses.

Stress associated with road transport is believed to be a significant contributor to the pathogenesis of post transport respiratory disease in horses. To determine the effects of road transport on pulmonary function, pulmonary aerosol clearance rates were measured in 4 horses 24 h before, and immediately after, 24 h of road transport by delivering aerosolised 99mtechnetium-labelled diethylenetriaminepentacetate (99mTc-DTPA) to the lungs and monitoring its washout. Each horse was transported twice, once while the trailer was equipped with a leaf-spring suspension and bias-ply tyres (trailer's original equipment, smooth ride) and once while the trailer was equipped with a torsion-bar suspension and normal pressure radial tyres (rough ride) in order to generate different ride characteristics. Before transport, blood was drawn from each horse for haematology and measurement of serum cortisol concentration; 24 h rates of hay and water intake and faecal output were recorded for each horse. Horses were then transported, 2 at a time, over a 128 km circular route of predominantly rural freeways at a constant speed of 72 km/h for 24 h. Horses were rested by stopping the trailer every 3.75 h for 0.25 h. During transport, heart rates (continuous 1 min averages), rates of hay and water intake and rates of faecal output were measured. Ammonia (NH3) and carbon monoxide (CO) concentrations were measured within the trailer and temperatures (wet bulb [WB], dry bulb [DB] and black globe [BG]) within the trailer were recorded each minute. Immediately after each experiment blood was drawn for haematology and measurement of pulmonary aerosol clearance rates were measured. For control studies, horses were housed in their stalls while heart rates were measured for 24 h. Slopes calculated from the 99mTc-DTPA clearance curves for pretransport horses were not significantly different from post transport clearance slopes. Pretransport mean 99mTc-DTPA clearance half-lives (T50, left lung mean +/- s.d. 41.7 +/- 15.8 min, right lung 44.6 +/- 19.1 min) were not significantly different from post transport T50 (left lung 53.5 +/- 14.0 min, right lung 52.0 +/- 11.6 min). Heart rates during transport were not affected by suspension type or trip order (the horse's first or second transport experiment) and were not significantly different from stall controls after the first 120 min of the experiment. Horses had increased red blood cell count, packed cell volume, haemoglobin, plasma protein and cortisol concentrations, and decreased body weights immediately post transport, indicating slight dehydration. Water and hay intake rates were significantly lower during transport than pretransport. Temperatures within the trailer were highest in the midafternoon and lowest in the early morning hours, but all temperatures measured in the trailer were within the comfort zone for large homeotherms. Ammonia and CO concentrations in the trailer during the transport period were within acceptable limits for human exposure. However, respirable articulates in the atmosphere were elevated above safe concentrations for human exposure.

Computational Models for Multilayered Composite Shells with Application to Tires

Abstract This paper focuses on four tire computational models based on two-dimensional shear deformation theories, namely, the first-order Timoshenko-type theory, the higher-order Timoshenko-type theory, the first-order discrete-layer theory, and the higher-order discrete-layer theory. The joint influence of anisotropy, geometrical nonlinearity, and laminated material response on the tire stress-strain fields is examined. The comparative analysis of stresses and strains of the cord-rubber tire on the basis of these four shell computational models is given. Results show that neglecting the effect of anisotropy leads to an incorrect description of the stress-strain fields even in bias-ply tires.

Influence of Suspension, Tires, and Shock Absorbers on Vibration in a Two-horse Trailer

Combinations of vehicle suspensions (leaf-spring and torsion-bar), tires bias-ply (311 kPa), normal-pressure (344 kPa) and low-pressure (172 kPa) radials, and shock absorbers were evaluated for smoothness of ride and common frequencies of vibration using a two-horse, bumper-pull, tandem-axle, forward-facing trailer. Accelerations on the x-axis (dorsal-ventral, upward-downward) were measured on each wheel and each corner of the trailer while the trailer was driven over fourteen 25-mm-diameter cables spaced at 4.8-m intervals at three speeds (40, 56, and 72 km/h). Twelve combinations of suspension, tires, and shock absorbers were tested in all. Initially, five steel barrels filled with 1 000 kg of water (total mass) were positioned in the trailer to mimic the body masses of two horses. The leaf-spring suspension with low-pressure radial tires and without shock absorbers provided the smoothest ride in terms of the lowest root mean square (rms) accelerations (P < 0.05), but the leaf-spring suspension combined with bias-ply tires and without shock absorbers also had similarly low rms accelerations. The torsion-bar suspension combined with normal-pressure radial tires was the roughest (in terms of rms accelerations) combination tested. Generally, the addition of shock absorbers did not improve ride quality in terms of x-axis acceleration. Several combinations of suspension and tires (leaf-spring suspension with bias-ply, low-pressure and normal-pressure radials, and the torsion-bar suspension with normal-pressure radials) were chosen to test with four live horses riding in the trailer (horses were transported two at a time). Root mean square acceleration values (x-axis only) were measured on the left and right front trailer subframe, the left front hoof and left trunk of one horse, and the right front hoof and right trunk of another while the trailer was driven over smooth and rough roads. The leaf-spring suspension with low-pressure radial tires provided the smoothest ride. Horses traveling on the right side of the trailer experienced more vibration than horses on the left side of the trailer, perhaps because of the poor conditions of asphalt roads near the shoulders.

Field Evaluation of Skidder Tire Tractive Performance

Tractive performance was evaluated under field conditions for a cable skidder equipped with seven combinations of bias-ply tires and one set of radial-ply tires. Traction performance variables and maximum pulling capacity were measured on forested and haul road surfaces. Little difference in maximum pulling capacity was found among the four widest tire combinations tested: 6850-32s, dual 6843-25s, dual 30.5L-32s, all bias-ply construction, and 6868-25 radial-ply tires. Single 28L-26s and 6843-25s operated at two different inflation pressures had the lowest maximum pulling capacity, but the results for the 6843-25s appeared to be biased because of wet site conditions. A net traction-slip model was presented and its parameters estimated using regression. Results indicated that the model accounted for a large proportion of the variability in the net traction/slip data but tended to overpredict net traction at low and high slip and underpredict at intermediate slip. Tire width did not appear to influence the model parameters consistently. The test surface, however, did affect bias-ply tire performance, with the field surface tending to lower the rate at which net traction ratio approached its maximum value, indicating lower tractive efficiency. This was not true for the radial-ply tires, which appeared to be as efficient on either surface.