Tractor Speed Research Articles

Research on Deposition Characteristics of a New Air-Assisted Electrostatic Sprayer

This study evaluated the properties of a new double air-assisted electrostatic orchard sprayer, focusing particularly on the impact of its electrostatic system on droplet deposition. The sprayer featured 10 nozzles, a centrifugal fan, and an axial fan, with an overall flow rate of 3.5 L/min and nozzle air velocities of 25 m/s (interior) and 12.5 m/s (exterior). Droplet sampling was conducted using paper cards and ponceau solution as a tracer. Field measurements in a Y-tree trained pear orchard assessed the effects of tractor speeds (0.34, 0.52, 0.84, and 1.05 m/s) and sampling positions (exposed and hidden faces). Tractor speed did not significantly affect overall droplet density, but the normalized droplet density on the exposed face increased with speed, while it decreased on the hidden face. The average normalized droplet density at all speeds was approximately 114.6 dot/cm2. The electrostatic system improved droplet deposition on the hidden face of leaves, particularly on the side of the tree near the sprayer. The coefficient of variation (CV) of the exposed face increased with tractor speed, while tractor speed had no impact on the CV of the hidden face. Overall, the electrostatic system reduced the CV. This research offers valuable insights into the use of electrostatic sprayers.

Thermo-mechanical coupling characteristics of the shearer’s guiding shoe during the friction

The reliability and longevity of the guiding shoe are crucial for the proper functioning of coal mining machines. The heavy wear of the sliding surface under thermal stress coupling is the primary factor influencing the service life of the guiding shoe. To reveal the heat flow distribution patterns and the thermo-stress coupling mechanisms of the guiding surface, a thermo-mechanical coupling model of the guiding shoe and the pin row is established. The transient thermodynamic behavior of the guiding shoe under different load and speed conditions is studied using the coupled temp-displacement analysis method in Abaqus. The results indicate that the overall temperature of the guiding shoe friction surface experiences a rapid increase during the initial running-in phase, followed by a progressively slower temperature increase over time. Temperature and stress concentration regions on the friction surface primarily localize at the corners of the shoe groove, and the distribution of temperature and stress shows a strong coupling. Furthermore, elevated traction speed and mechanical load exacerbate the thermo-elastic instability of the guiding shoe, consequently augmenting thermal stress on the friction surface. The increase in support load results in significant thermal shock on the lower area of the left side of the guiding shoe. The research provides a reference for exploring the fatigue failure and wear mechanisms of the guiding shoe while considering thermal effects.

Instrumentation in Tractor for Evaluating Performance of a Tractor Drawn Rotavator

Performance measurement of agricultural machinery is essential for enhancing their efficiency for which they are operated. The performance related data helps the operator to select optimum operating parameters which reduce fuel consumption and increase field productivity. This study was aimed to develop various sensing units and install them on the tractor for evaluating performance of a tractor drawn rotavator. A microcontroller based embedded system was developed for continuous recording of wheel slip, actual forward speed, throttle opening, engine speed, velocity ratio, draft and power take-off (PTO) torque related data while carrying out tillage operation with rotavator. The wheel slip (from 1.5% to 35%) and actual forward speed of the tractor (up to 6 km h-1) was measured using inductive proximity sensors. For measuring throttle opening (0 to 100%), engine speed (750 to 2500 rpm), draft (65 to 350 kg) and PTO torque (up to 420 N-m) values, a potentiometer, magnetic pickup sensor, S-type loadcell and PTO torque transducer, respectively, were used. For computing velocity ratio, peripheral speed of rotavator was measured using PTO speed data received from PTO torque transducer, and actual forward speed of tractor was measured using inductive proximity sensor. The developed sensing units were calibrated under both dynamic and static conditions, and were also verified in laboratory and field conditions. Results showed that output signals received from the sensing units varied linearly with applied load. The mean absolute percentage error (MAPE) between measured and actual values was found to be below 5%. From the measured parameters, specific energy requirement and total power required for carrying out tillage operation could be computed. The power requirement was found to increase with increase in both gear and throttle settings. The specific energy requirement was minimum when rotavator was operated in L2 gear of the tractor. The minimum specific energy of 21 Wh m-3 was found at L2 gear and 75% throttle opening.

Model predictive control with real-time variable weight for civil aircraft towing taxi-out control systems

Unlike the traditional method of taxying, where civil aircraft reach the runway by relying on their engines, the new mode of towing taxi-out may become preferred because of its lower energy consumption, lower emissions, and higher efficiency. To improve the tracking accuracy and lateral stability of the towing system, this study used a two-level time-varying weight control method (RMPC) based on model predictive control (MPC) and fuzzy control. The tractor speed and front wheel angle were set as the control variables in the MPC controller, and the real-time lateral displacement error and yaw angle error of the tractor were set as the fuzzy control inputs. The influence of the weight matrix on the accuracy and stability of path tracking was coordinated by online optimization of the MPC objective function weight. The simulations of multiple working conditions were performed using TruckSim software in Simulink, which showed that the proposed control method can limit the lateral displacement error of the tractor and aircraft within 0.4 m, which can be reduced by 70.83% and 77.4% compared with the single MPC, respectively. Additionally, the maximum yaw angle errors of the tractor and aircraft are reduced by 76.11% and 51.31% compared with the single MPC, respectively. Furthermore, the yaw angle error of tractors can be limited to 4° and that of aircraft can be limited to 6.5°, which is an improvement of the lateral stability and driving safety for the civil aircraft towing system. The new controller may provide technical insights and support for the practical development and safe application of the towing taxi-out mode.

Process optimization of continuous aramid fiber reinforced PA12 filaments and printed composites

AbstractA multi‐stage fiber spreading process for the preparation of high‐performance continuous aramid fiber reinforced nylon 12 (CAF/PA12) composites was proposed in this paper. The effects of spreading rod crown radius, spreading rod axis height and traction speed on fiber impregnation effect and filaments properties were investigated. The fiber volume fraction of the prepared filament was approximately 30%. And the maximum tensile strength and modulus of the filaments were 839.89 MPa and 41.35 GPa, which were 34.36% and 34.30% higher than unspreading filaments, respectively. The influences of printing process parameters such as printing temperature, the combination of layer thickness and printing spacing on the transverse tensile properties of the specimens were studied. Printed specimens reached a transverse tensile strength and tensile modulus of 13.988 MPa and 1.293 GPa, respectively. The influences on low velocity impact properties of the specimens were also investigated in terms of impact energy and printing stacking sequences. Results revealed that the impact threshold energy of orthotropic ([0/90/0/90]2) specimens was 50 J. Quasi‐isotropic ([0/45/90/−45]2) specimens exhibited the superior impact resistance with an impact load of 4.939 kN. Macro‐ and micro‐matrix crack, surface buckling, fiber fracture and delamination were the main failure modes of the specimens.Highlights A novel thermoplastic composite filament forming process was proposed, and the filament forming equipment was designed and manufactured. Continuous aramid fiber‐reinforced PA12 filaments with about 30% fiber content were prepared by orthogonal tests under different forming process conditions, which showed maximum tensile properties of 839.89 MPa and 41.35 GPa, respectively. Spreading multiplication was positively related to filament tensile properties, which was major affected by the axial height of the spreading rod. Transverse tensile strength (13.988 MPa tensile strength and 1.293 GPa tensile modulus) of printed specimens was investigated under different printing parameters. Fiber orientation had a significant effect on the low‐velocity impact properties. Micro‐ and macro‐matrix crack, surface buckling, fiber fracture and delamination were the main failure modes of the low‐velocity impact specimens.

Traction resistance analysis and cutting state recognition of shearer based on numerical simulation

Accurate identification of the shearer cutting state is essential for the intelligent control of the shearer. In addition to the coal-rock strata conditions, the operational parameters of the shearer also influence the shearer cutting state. To analyze the factors on the shearer cutting state and accurately identify its cutting state, the characteristics of shearer traction resistance are analyzed under various working conditions using discrete element numerical simulation. A method of the shearer cutting state recognition based on traction resistance and traction speed is proposed. Firstly, the mechanical properties of coal and rock are obtained through uniaxial compression experiments. The joint simulation model is developed to analyze the change in traction resistance under different traction speeds. The functional relationship between traction resistance and traction speed is obtained. Then, the influence of gangue thickness and position on traction resistance is analyzed. The time domain and frequency domain analysis of traction resistance is conducted to more accurately describe the characteristics of shearer traction resistance. Finally, simulation and experimental data are used to verify the reliability of the proposed method. The recognition accuracy of simulation and experimentation reaches 100 % and 97.1 %, respectively. This indicates that the proposed method can effectively recognize the shearer cutting state.

Investigating the Impact of Speed and Tire Pressure of a Wheel Tractor on Soil Properties: A Case Study in Northeastern Uzbekistan

In agriculture, machines engaged in various agrotechnical activities and operations have different impacts on the soil. The effect of mechanization is primarily reflected in two indicators: soil density and hardness. At the same time, considering the direct dependence of tractive resistance on soil hardness in processing machines and sprayers, we studied subsequent changes in the soil in the path of wheels affected by the soil after the passage of four-wheeled and three-wheeled tractors. We also examined various atmospheric pressures in the tractor’s tires and the impact of different types of tires on soil compaction and traction. The studies showed that to reduce the compression impact on the soil of four-wheeled tractor working systems during certain technical operations, it is necessary to choose the maximum permissible travel speed and the minimum air pressure in the tires specified in the technical conditions. This approach helps to decrease soil compaction and maintain its structure. Additionally, it was found that three-wheeled tractors exert less pressure on the soil compared to four-wheeled ones, which should also be considered when selecting equipment for different agrotechnical tasks. Optimizing tire pressure and tractor speed is crucial for minimizing negative soil impact and enhancing the efficiency of agricultural operations.

Calculating the Total Costs of the Tractor and the Chisel Plow under Variable Speeds and Depth of Tillage

Factorial experiments were conducted in a silt clay loam soil with a randomized complete block design with three replications for each treatment. This study aimed to calculate machinery unit costs and some indicators during primary tillage, under variable tractor speeds of 1.8, 3.5 and 5.7 km.h-1 and depth of plowing 20, 30 and 40 cm. A higher speed of 5.7 km.h-1 is associated with higher practical productivity of 0.9696 ha.h-1; specific productivity of tillage 4309 m.h-1; a volume of soil disturbed 2884 m3. h-1. The best fixed, management, total tractor, total plow and total machinery unit costs were 2.27, 0.80, 9.02,1.01 and 10.04 $.ha-1 respectively. Additionally, lower fuel consumption was 8.56 l.ha-1, and the actual time for plowing one hectare was 1.02 h. The depth of tillage 20 cm recorded a higher productivity of 0.6412 ha.h-1, the specific productivity of tillage was 2849 m.h-1, less fuel consumption of 7.74 l.ha-1, less actual time of plowing one hectare of 1.95 hThe least fixed, variable, management, total tractor, total plow and total machinery unit costs were 4.32, 4.71, 0.89, 9.94,1.94 and 11.89 $.ha-1 respectively. All interactions among the treatments were significant. The experiment concluded that the plowing depth has a greater effect than speed on all operating costs of the tractor and chisel plow and performance indicators. The correlations among the indicators studied were direct (positive) and inverse (negative) significantly and were also non-significant.

FIELD COMPARISON OF THE PERFORMANCE OF SLATTED AND GENERAL PURPOSE MOLDBOARD

Factorial experiment within randomized complete block design using three replication for field comparison performance slatted and general-purpose moldboard plow. Using least significant design (LSD) 1 % and 5 % was used to compare the mean of treatments. Three factors were used, the first one was depths of tillage 15 and 25 cm, the second was speed of tractor 4.146 and 7.224 km/hr, and the third factor was types of moldboard, slatted and general-purpose moldboard. Slatted moldboard recorded the least slippage of 9.697 %, the fuel consumption of 23.580 L/ha and higher effective field capacity of 0.4239 ha/hr, and field efficiency of 72.543 %. Depth of tillage 15 cm got the least slippage of 6.364 %, fuel consumption of 20.182 L/ha and higher and higher effective field capacity of 0.4402 ha/hr, and field efficiency of 74.187 %. Speed 7.224 km/hr got least fuel consumption 22.939 L/ha and a higher adequate field capacity of 0.5246 ha/hr. Interaction between treatments had a significant effect.

Comparative study on the causes of rail corrugations in long steep-grade sections under traction and braking conditions

There are significant differences in rail corrugations between the uphill and downhill sections in long steep-grade sections. Comprehensive field investigations and numerical simulations are conducted to investigate rail corrugations under traction and braking conditions. Firstly, field investigations of rail corrugations in long steep-grade sections are carried out. Secondly, the dynamic models of the vehicle-track system under uphill traction and downhill braking conditions are constructed, and the dynamic characteristics of the vehicle-track system are explored. Then, the finite element models of wheel-rail-traction/brake systems are constructed, and the friction self-excited vibration characteristics of the wheel-rail system are studied by the complex eigenvalue method. Finally, the influences of key parameters of traction and brake friction pairs on rail corrugation are studied, and suppression methods of rail corrugations are proposed. The results show that (1) rail corrugation more easily occurs on the transition positions of the easement curve and circular curve, with slope changing. (2) Under the traction and braking conditions, rail corrugations are induced by the friction self-excited vibration of the wheel-rail-traction/brake system. (3) Reducing the traction speed or increasing the gear mesh stiffness, reducing the brake friction coefficient or the brake force can suppress the rail corrugation.

The influence of traction speed on the microstructure and properties of vacuum horizontal continuous casting Cu–5Fe–0.15Sn alloy

The Cu–5Fe–0.15Sn alloy was prepared using the vacuum horizontal continuous casting method, followed by comprehensive microstructural analysis using optical microscopy (OM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results highlight a significant impact of traction speed on both microstructure and properties. As traction speed increases, there is a notable reduction in the size of primary Fe phases, leading to a more uniform distribution of Fe phases. Initially, hardness experiences an increase followed by a subsequent decrease, while electrical conductivity exhibits an inverse trend. The dendritic and globular Fe phases undergo a transition into Fe fibres following multi-stage deformation heat treatment. Furthermore, the Fe fibres and precipitated Fe phases exhibit smaller, denser, and more uniformly distributed characteristics with increasing traction speed. At a traction speed of 0.15 m/min, the Cu–5Fe–0.15Sn alloy showcases peak tensile strength and electrical conductivity values of 826 MPa and 67% IACS, respectively. These values surpass those attained through other traction processes, indicating superior overall performance of the alloy fabricated at a traction speed of 0.15 m/min.

Design of fast braiding process based on reconstructing mesh with complex and irregular mandrels

Circular braiding of large-sized and complex irregular structural components is widely used in fields such as aerospace and rail transit. However, existing braiding process design and simulation algorithms lack applicability to mandrels with complex features, such as flanges, concave corners, holes, and hollows, which also have low calculation efficiency in the braiding process simulation. This study first proposes an optimization algorithm for the complex features on the mandrel surface, improving the applicability for the braiding process design of complex and irregular mandrels. Then the mandrel mesh was reconstructed, greatly improving the computational efficiency of the braiding process design process. Finally, a fast iteration method based on the mandrel reconstructed mesh was proposed to achieve the fast calculation of process control parameters, including traction trajectory and traction speed, as well as the prediction of forming quality for the braiding angle and coverage rate. The experiment shows that the algorithm improves the applicability of the multi-braiding angle process and shortens the sampling cycle of braiding process design by more than 60%.

Field Sprayer with Application Rate Control Using Fast Response Proportional Valves under Variable Speed Conditions

In modern agriculture, which is characterised by dynamic field environments, challenges are faced in maintaining consistent application rates due to varying tractor speeds, field conditions, and certain calibration errors. Conventional control systems, which rely on slower valves, have difficulty adapting to these dynamic field conditions. By contrast, the integration of fast-acting proportional valves improves the precision and flexibility of flow rate adjustment during spraying applications. This research focused on evaluating the accuracy of spraying applications under different tractor speed conditions through field experiments and data analysis. This study involves a field sprayer with boom wings divided into right and left sections, where the flow rate of the liquid to each section is controlled by proportional valves with a 3 s full opening and closing time, dependent on speed information. Using a closed-loop control system consisting of a flow meter, proportional valve, and PLC, the valves are controlled by the PLC’s internal PID blocks. Observations reveal that as the tractor speed increases to a certain level, the system effectively adjusts the application rate close to the target value and maintains control against the changing ground speed during all field tests. The study included five different application tests, with target application rates of 100, 150, 200, 250, and 300 L ha−1, with each repeated three times, resulting in a total of 15 field tests at different ground speeds. During these tests, the data were meticulously recorded every second, covering the tractor speed, flow rate, and pressure values for both right and left boom sections, along with regulator pressure, proportional valve opening rates, and application rates. The durations for each application rate were documented alongside instances within specified periods where error boundaries of ±10% were exceeded. During the total test duration of 9734 s, the actual application rate value exceeded error boundaries during only 209 s. Within the application durations, the speed variation intervals ranged from 5.10 to 10.23 km h−1, 4.64 to 9.91 km h−1, 3.68 to 7.89 km h−1, 4.80 to 8.21 km h−1, and from 4.90 to 8.69 km h−1. The absolute percentage mean application errors were recorded as 2.81%, 2.68%, 2.28%, 2.14%, and 2.51% for respective application rates. Furthermore, statistically significant correlations (p < 0.01) were identified among the variables (speed, valve opening rate, flow rate, pressure) in both the right and left boom sections across all application rates.

Numerical study of forces acting on the drum cutting coal with gangue.

A coal model containing gangue was established by discrete elements to study the forces occurring when a shearer cuts coal, and a rigid-flexible coupled shearer section model was established in RecurDyn; the drum cutting process was simulated through bidirectional coupling. The dynamic distribution of the force chain was obtained when cutter teeth cut the coal rock. During the cutting process, the coal rock failure is caused by normal and tangential forces, with the latter having a major role. The ratio of the average tangential force to normal force was 1.34~1.79. When the rock is in the middle of the coal seam, the force (including normal and tangential forces) on the rock is the highest. Moreover, the force on the rock-coal interface is greater than that on the coal-rock interface. The results show that the force on the coal decreases with the increases in rotation speed. In contrast, the number of broken bonds increases. Further, the number of broken bonds and the force of coal increased nonlinearly with traction speed. Finally, the increase of tooth mounting angle decreased the force on the coal rock and the number of broken bonds, followed by an increase. As such, this study provides a reference for further theoretical research on forces in coal cutting.

Experimental and numerical evaluation for drum dynamic reliability under extremely complex working conditions

Coal mining machine drums are prone to damage and malfunction under extremely complex working conditions, which seriously affects the efficiency and safety of coal production. In this paper, based on the theory of coal rock cutting and virtual simulation technology, finite element models of drum cutting coal rock were established and then verified by physical experiments. Through simulation analysis, the dynamic reliability of the drum was studied from three aspects: load, stress and wear, and a mathematical model of drum load was established with respect to the traction speed and drum rotation speed; based on the orthogonal test, the optimal working parameters to improve the wear resistance of the drum were derived. The results of the study found that when the traction speed increases, the load on the drum increases, and when the drum rotation speed increases, the load on the drum decreases; when the traction speed is increased from 2 to 6 m/min, the stress on the pick body under different rotation speeds increases to different degrees, with an average increase rate of 27.394%; when the drum rotation speed is 90 r/min, the traction speed is 3 m/min, and the coal loading mode is projectile loading, the wear depth of the picks and spiral blades is relatively small. The research method and results of this paper can provide a reference for the selection of the drum working parameters.

Shearer parameter optimization and low energy consumption mining based on 3D point cloud characterization of coal wall

AbstractTo achieve efficient and low energy consumption mining under different cutting depths of a shearer, a multiparameter coupling optimization method for the shearer based on three‐dimensional (3D) characterization of the coal wall was proposed. First, a seven‐axis absolute articulated arm measuring machine was used to obtain 3D point cloud data of the coal wall, and then the 3D of the coal wall surface was reconstructed by using segmentation, filtering, and stitching processing, thereby obtaining the average thickness of different coal wall areas. Second, through the quadratic rotation regression orthogonal combination experiment, the optimal combination of drum speed, traction speed, and cutting depth was obtained, further obtaining the order of primary and secondary influences, and the regression model. Moreover, a particle swarm optimization algorithm was used to obtain the optimal drum speed and finally, the laboratory and field test experiments were conducted to verify the effectiveness of the proposed optimization algorithm in reducing the cutting energy consumption of shearer. The experiment results show that the given optimization algorithm can adaptively optimize the traction speed and drum speed based on the corresponding cutting depth, which significantly reduces the cutting specific energy consumption of the shearer. Thus, it provided an important technical means for the shearer to achieve low energy consumption and efficient mining.

Dynamic Analysis of the Guiding Shoe considering Contact Gap and Pose Disturbance

The pose disturbance of the guide shoe under complex working conditions can lead to collision, impact, and wear failure between the guide shoe and the pin row. To explore the damage law of pose disturbance on the guiding shoe, a rigid‐flexible coupling dynamic model of the walking mechanism considering the contact gap between the guiding shoe and the pin row was constructed. The contact characteristics of the guiding shoe under different poses were analyzed. The results indicate that the swing around the x‐axis has the most significant impact on the guiding shoe, with stress concentration primarily occurring near the corner of the trench. The posture of swinging solely around the y‐axis weakens the supporting effect of the guide shoe, resulting in stress concentration on the end face of the left side face. Swinging around the z‐axis results in stress concentrations on the upper faces of the shoe. Research shows that the angular velocity of the guiding shoe around the x‐axis and z‐axis is highly sensitive to variations in traction speed. In addition, an increase in lateral force weakens the support effect of the guiding shoe, resulting in elevated contact force on the lower side of the guiding shoe and increased y‐direction load on the walking wheel. The research results provide a reference for exploring the influence of walking unit postures on the failure of the guiding shoe and for improving shearer traction reliability.

امكانية تقليل الفقد الكمي والنوعي باستخدام قالعة البطاطا

A field experiment was conducted in one of the fields of the Technical Institute in Shatrha for the spring season 2022 to study the effect forward speeds (2.50, 3.18 ,3.60 km. hr-1), and two levels of conveyor speeds (43, 49) m. min-1 and two level of type of chain conveyor of rubber bars and clothes -coated in possibility of reducing the quantitative and qualitative losses by using the potato digger. quantitative loss, qualitative losses, and field efficiency were studied in this research. The randomized complete block design with three replications was used in the research. The results showed that the tractor speed 2.50 km.hr-1 in gets the quantitative losses which amounted to1.40 %, and the qualitative losses amounted to 11.1%, and the tractor speed 3.60 km. hr-1 gets the heights Field efficiency amounted to 84.80%.

Thorough Analysis of the Reliability of Measurements on Chassis Roller Dynamometer and Accurate Energy Consumption Estimation for Electric Vehicles

The energy consumption of the electric test vehicle on the roller dynamometer test bench is thoroughly investigated in this work. Initially, we extensively examined the relevant testing approaches on chassis dynamometer test benches. Then, we presented the main issues and limitations of this type of testing facility. After that, an experimental analysis was performed by recording the NEDC and the WLTP-class 2 standard driving cycle test data. It was found that the power consumption associated with specific test maneuvers could be accurately simulated via the roller dynamometer system. However, the experimental test results showed some disparities compared to the expected results from the simulation models. These findings supported identifying the dynamic behavior resulting from the tire and roller contact. The LuGre friction model provided the solution, incorporating friction-related physical models such as stick-slip and the Stribeck effect. In addition, adjustments were made to the LuGre model to consider the dynamic influences of the roller on the tire. Finally, we created a systematic estimation model for energy consumption by integrating the boundary conditions of the test bench, a generic model for energy estimation of electric vehicles, and the proposed tire–roller contact model. The overall model requires only the measured traction speed of the test vehicle and the auxiliary energy losses as physical inputs. The results proved that the proposed model enabled the estimation of the total power consumption with high accuracy.

Multibody Dynamics Modeling of a Continuous Rubber Track System. Part 2—Experimental Evaluation of Load Prediction

<div>Vehicles equipped with rubber track systems feature a high level of performance but are challenging to design due to the complex components involved and the large number of degrees of freedom, thus raising the need to develop validated numerical simulation tools.</div> <div>In this article, a multibody dynamics (MBD) model of a continuous rubber track system developed in Part 1 is compared with extensive experimental data to evaluate the model accuracy over a wide range of operating conditions (tractor speed and rear axle load). The experiment consists of crossing an instrumented bump-shaped obstacle with a tractor equipped with a pair of rubber track systems on the rear axle. Experimental responses are synchronized with simulation results using a cross-correlation approach.</div> <div>The vertical and longitudinal maximum forces predicted by the model, respectively, show average relative errors of 34% and 39% compared to experimental data (1–16 km/h). In both cases, the average relative error is lower for tractor speed from 1 to 7 km/h, namely 20% and 35%. The model and experimental amplitudes spectra of the force signals are compared using the coefficient of determination <i>r</i><sup>2</sup>. In the 1 to 7 km/h tractor speed range, the average vertical and longitudinal coefficients of determination are, respectively, 0.83 and 0.42. The coefficients, respectively, reduce to 0.27 and 0.14 for speeds over 7 km/h.</div> <div>In summary, the model can predict the maximum vertical and longitudinal forces in addition to the amplitude spectrum of those signals for operating conditions up to 7 km/h, regardless of the rear axle load, with accuracy acceptable for many applications, such as load case determination for preliminary structural design. Several factors affecting the accuracy of the model at higher tractor speed are identified for future work including suspension creeping, suspension compression characterization at high strain rates, and temperature dependence of material properties.</div>