Traction Performance Research Articles

СИСТЕМНИЙ ПІДХІД ДО ОЦІНЮВАННЯ ЕКСПЛУАТАЦІЙНИХ ЯКОСТЕЙ СІЛЬСЬКОГОСПОДАРСЬКИХ ТРАКТОРІВ

Purpose of the study. Formation of a methodology for systematic evaluation of performance in agricultural tractors. Research methods. The methodological basis for evaluating the performance of agricultural tractors is the OECD Code 2. Code 2 of the OECD standardizes test methods. Determination of traction indicators for tractors is carried out by the method regulated by the SOU L. Pogorslyy UkrNDIPVT 71.2-37-046043090-017:2015. A measuring and registration complex is used. When evaluating the functional accuracy of the tractor, according to DSTU 7463:2013, indicators are analyzed that determine the traction class of the tractor, energy capabilities and aggregation. An analytical method and a comparative analysis with the results of experimental studies are used to form a scientific problem, determine the purpose and set the objectives of the study. The results of the study. The research results develop a methodology for a systematic approach to assessing the operational quality of agricultural tractors. Direction of research to improve the technical, economic and agro technical properties. New dependencies are proposed (they use the method of partial accelerations) for estimating the traction and energy performance of the tractor, handling and driving stability, and braking properties. A technique for estimating the dynamic properties of a tractor as part of a tillage unit in an unsteady mode of its movement on the rut is substantiated. Code 2 of the OECD standardizes the testing methodology for agricultural tractors regarding the evaluation of their performance under nominal technical condition. The results of the studies that are given in the article prove that the deviations of real functional parameters from the nominal ones significantly affect the performance of the tractor. Conclusions. According to the results of the research carried out, the classification of the performance of agricultural tractors was carried out according to their traction and agro technical properties. The research results made it possible to formulate the main theoretical and scientific-practical conclusions. A methodology for a systematic approach to assessing the performance of agricultural tractors has been formulated, based on the substantiated method of partial accelerations. Using the method of partial accelerations, the dependences of the effective power of the engine, the efficiency of the tractor, the mass and resistance of the agricultural machine aggregated with the tractor, the braking properties of the tractor, its controllability and driving stability on the rut are substantiated. Analytically proved and experimentally confirmed the instability of the traction force of the tractor, the resistance of the agricultural machine of the tillage unit, the dynamic performance of which exceeds the average values by 2.5-3.0 times. Keywords: tractor, system approach, operational properties, traction properties, controllability, braking properties.

МЕТОДИКА ВИПРОБУВАНЬ ЩОДО ОЦІНЮВАННЯ ЕКСПЛУАТАЦІЙНИХ ЯКОСТЕЙ СІЛЬСЬКОГОСПОДАРСЬКИХ ТРАКТОРІВ ЗА КОДЕКСОМ 2 ОЕСР

Purpose of the study is new provisions for testing agricultural tractors, evaluating their performance, which implement the OECD Code 2 Research methods. The testing of the tractor and its main elements is based on the method of partial accelerations, the basis of which is the solution of the inverse task of the dynamics: the acting forces are estimated from the acceleration. The method and means of measurement (developed in the L. Pogorilyy UkrNDIPVT Kharkiv branch) are effectively used in testing tractors and its main elements. The results of the study. The proposed express methods make it possible to reduce the time for testing and timely identify shortcomings in the operation of the systems being tested. The proposed express test method for the cylinder-piston group provides the ability to timely identify shortcomings in the operation of engines. It has been established that the most efficient operation of the tested unit is when the tractor is not fully loaded. The stability of the movement of the transport-technological unit is interconnected with its controllability, which is determined by the technical condition of the steering. The relationship between the investigated values of the angular accelerations of the steering wheel of the tractor and the aggregated machine is provided with a reliability of 95 %. To determine the braking properties, an indicator is proposed that characterizes the growth rate of the tractor deceleration during braking. To evaluate the quality of functioning of the hydraulic drive of the tractor mounted system in the case of unstable technical condition of its elements, it is necessary to start with the evaluation of the fluid flow in the hydraulic cylinder and end with the analysis of the flow in the bypass valve. Conclusions. Code 2 of the OECD normalizes the methodology for operational testing of agricultural tractors, on the basis of which in L. Pogorilyy UkrNDIPVT Kharkiv branch developed industry standards for assessing the traction and energy performance of tractors. It has been theoretically and experimentally proved that in the performance tests of tractors and its main elements, the method of partial accelerations is effective, which is based on the reverse transition from the vector sum in the space of forces that act on the tractor to the vector sum in the space of accelerations. This method allows you quickly assess the performance of tractors when coupled with mounted and trailed agricultural machines, as well as the technical condition of the main elements of the tractor design. Keywords: tractor, tests, OECD Code 2, main elements, malfunctions, express methods

Penilaian Kinerja Keuangan Menggunakan Metode Economic Value Added (Eva) Pada PT United Tractors, Tbk

This study aims to analyze the financial performance of PT United Tractors, Tbk using the Economic Value Added (EVA) method. The data analysis technique used in this research is quantitative descriptive analysis. The technique used for data collection is using documentation techniques. The results of the study show that the calculation of Economic Value Added (EVA) at PT United Tractors, Tbk from 2017-2021 produces a positive EVA value or the EVA value produced by PT United Tractors, Tbk is greater than zero (EVA > 0). This shows that the company has generated economic value added. Even though the net profit generated by PT United Tractors, Tbk from 2017-2021 has fluctuated, PT United Tractors, Tbk was able to generate economic value added for the company. This positive EVA value is caused by the NOPAT value which exceeds the cost of capital, so that company management is able to create economic value added for the company and investors, so that it can be said that the financial performance of PT United Tractors, Tbk is in good condition.

MATHEMATICAL MODEL OF THE ACCELERATION PROCESS OF A WHEELED TRACTOR WITH CONSIDERING THE FUEL SUPPLY AND THE OPERATION OF THE HYDRO-CLAMPING CLUTCH

Analysis of Ukrainian production of wheeled tractors shows its rapid decline, due to many reasons, the main of which is the obsolete use of tractor technology, which affects the technical and operational performance, ergonomic and others. Today, most foreign wheeled tractors use the latest technology in the design of internal combustion engines, transmissions and wheeled engines. In particular, there is a greater bias towards the use of continuously variable transmissions. In order to create real competition for domestic producers, it is necessary to implement modern solutions, which is not possible without quality cooperation with scientists. Therefore, the material of this article aims to form guidelines for mathematical modeling of the dynamics of the wheeled tractor, taking into account the operation of the main clutch, hydraulic clutch and fuel control in the internal combustion engine. In solving this goal, a technique was used that provided mathematical modeling of the crankshaft of an internal combustion engine with the available harmonic components, as well as the ability to control the fuel supply. The simulation of the transmission operation was based on classical approaches in the study of the dynamic load of the power plant, taking into account the operation of the main clutch and hydraulic clutches. As a result, the dependences of the change of technical and operational parameters of the wheeled tractor at the stage of start-up and acceleration are obtained. The practical significance of the work lies in the possibility of its use in assessing the performance of a wheeled tractor, which is equipped with preselective and continuously variable transmissions, as well as a transmission that uses dual-clutch technology.

SIMULATION MODELING OF TRACTION AND DYNAMIC INDICATORS OF TRACTORS ON THE BASIS OF POWERMIX FIELD CYCLES TEST

The paper presents a mathematical model for determining the traction and dynamic performance of tractors using PowerMix field test cycles. The mathematical model was successfully tested, during which a set of traction-dynamic parameters of a wheeled tractor with the maximum discrepancy on individual indicators relative to experimental data, which is -8.4… + 7.9%. A plan of a simulation experiment is proposed, which takes into account the distribution of the annual volume of spring and summer-autumn tractor work by typical agricultural operations, and includes loading traction cycles with power take-off through PTO and hydraulic system of the tractor. To assess the efficiency of tractors based on a set of traction-dynamic indicators obtained from field PowerMix test cycles, developed a method of bringing the simulation results to the performance of the base tractor with a capacity of 100 kW, which corresponds to the basic cycles PowerMix. The technique makes it possible to compare tractors of arbitrary design solutions and power. As an example, the results of modeling the traction and dynamic performance of the New Holland T6.180 tractor on PowerMix field test cycles determined the average values of productivity and per hectare of fuel consumption plowed by the base tractor, which are 1,239 ha / h and 14.58 kg / ha, respectively

TRACTION QUALITIES OF THE DRIVING WHEELS WHEN ROLLING THEM ALONG ONE TRACK

During rectilinear motion of a wheeled tractor on a deformable surface, its rear wheels move along the track formed by the front ones. The amount of soil compaction can be different depending on its physical and mechanical properties, the dimensions of the front wheels of the tractor, the weight load falling on the front axle, and the like. Accordingly, the traction abilities of the rear drive wheels will also be different. This circumstance should be taken into account when designing wheeled tractors, especially tractor-tractors with two driving axles, in which a change in any of the factors listed above, for example, the distribution of the load along the axles, affects not only the compaction of the surface on which the rear wheels move, but and on the traction qualities of the front. In the course of the research, it was found that with a decrease in the load distribution coefficient below 0.5, the role of the rear wheel, which is capable of developing a greater traction force than the front wheel at the same load, in the formation of the total traction force, decreases. Therefore, the total traction force of the driving wheels becomes lower. With an increase in this coefficient above 0.5, the amount of preliminary soil compaction by the front wheel decreases; as a result, the ability of the rear wheel to develop more traction than the front wheel under the same load is reduced. The greatest traction force of two driving wheels moving along the same track is achieved with the same weight loads. Thus, the position of the center of gravity of a tractor with four driving wheels of the same size should be chosen in such a way that the load on the front and rear wheels is equalized at the rated pull on the hook. When conducting research on a field prepared for sowing, with an active semi-trailer with different load distribution between the rear axle of the tractor and the axle of the semi-trailer, it was found that the center of gravity of the active semi-trailer can be selected in the same way as for the inactive one, i.e. taking into account the influence of the semi-trailer on traction performance. The dependences obtained in the work make it possible to analyze the traction qualities of several driving wheels when they roll along one track. With their help, it is possible to identify the effect of surface compaction on the traction qualities of the rear moving front wheels; the influence of load distribution along the axles of the driving wheels on their total traction force, etc.

Drawbar Performance of Tractor Tyres with Steel Spikes At 100%-Wheel Slip

Abstract A driving wheel is a part of a tractor, which transmits forces from a tyre to the ground. Therefore, it affects the tractor movement and the pulling of an implement. The paper is aimed at a tractive performance evaluation of special driving wheels based on drawbar pull at 100%-slip. These wheels consist of steel spikes to be applied in the base or working position. The design is characterized by the spikes placed in a tyre-tread pattern. The rubber lugs of the tyre are higher than spikes, therefore, they are not in contact with the ground in the base position. The spikes in the working position exceed the tyre diameter to be in contact with the ground. Tests were performed on a grass plot at a relatively low soil moisture. The spike tyres were compared with the standard tyres using a sub-compact tractor. An increase in drawbar pull reached a statistically significant value of 15.9% in the 2nd gear and 16.7% in the 1st gear.

Analysis and Comparison of Operational Characteristics of Electric Vehicle Traction Units Combining Two Different Types of Motors

This paper proposes a traction unit that combines an interior permanent magnet motor and a PM-assisted synchronous reluctance motor for electric vehicles to improve traction performance, enhance energy efficiency, and reduce cost. The characteristics of three traction units are analyzed and compared, including (a) rear-wheel-drive configuration using one IPM motor; (b) all-wheel-drive configuration using two interior permanent magnet motors; and (c) all-wheel-drive with a combination of one interior permanent magnet motor and one PM-assisted synchronous reluctance as proposed in this paper. The operational characteristics of each motor to achieve a wide constant power speed range are first investigated. Then, the Urban Dynamometer Driving Schedule is utilized to compare and evaluate the operational characteristics, energy consumption, and most importantly, the efficiency of the traction units. Simulation results reveal that the overall efficiency of the proposed traction unit can be improved compared to the other configurations. The advantages and drawbacks of the proposed traction unit are also investigated. Finally, experiments are conducted to validate the analysis.

Performance Evaluation of Seed-Cum-Fertilizer Drill

Abstract: The study was conducted in the farm of the institute to assess the performance of tractor operated seed cum fertilizer drill for sowing paddy seeds. It was observed that there was no effect of stubble on the performance of seed-cum fertilizer drill. However, the loose straw spread on the surface offers some hindrance in the working of the drill. The standards test code was adopted. Each test was replicated minimum three times. The forward speed and depth of sowing were taken as independent variables while wheel slippage and field capacity as independent variables. The field capacity, depth of sowing and seed rate were found to be 0.21 ha/h, 5.50 cm and 0.60 q/ha respectively as compared to 0.50 ha/h, 1.5cm and 1.25 q/ha in case of conventional broadcasting method. The mechanized method of sowing resulted in higher depth of sowing compared to broadcasting method. The tractor operated seed cum fertilizer drill was found to be better as compared to traditional broadcasting method. Keywords: Seed cum fertilizer drill, broadcasting method, Paddy sowing

Finite time trajectory tracking control of autonomous agricultural tractor integrated nonsingular fast terminal sliding mode and disturbance observer

A novel control strategy is proposed in this paper to improve the trajectory tracking performance of the autonomous agricultural tractor on both straight-line parallel tracks and headland turning curve tracks in the face of slippage, which combines the nonsingular fast terminal sliding mode (NFTSM) control with a kind of finite time disturbance observer (FDO). The designed FDO ensures robustness outside the sliding mode surface, while the constructed NFTSM ensures the fast convergence of tracking errors and chattering suppression. The effectiveness and advantages of the designed control strategy are verified by simulation comparison with the existing results under MATLAB/Simulink and CarSim co-simulation environment.

Artificial neural network to predict traction performance of autonomous ground vehicle on a sloped soil bin and uncertainty analysis

• ANN models were developed to estimate the AGV’s traction behavior on slopes. • Uncertainty analysis quantified the reliability and robustness of ANN model output. • ANN is a promising, robust, and reliable method to predict off-road vehicle’s traction performance. • Predictive traction models would empower the multi-AGV’s operation on a high slope. A fleet of autonomous ground vehicles (AGV) is envisioned to expand farming to arable land suitable for production except for being too steep for conventional equipment. The success of proposed multi-AGV system largely depends on the traction performance of the individual AGVs on unevenly sloped terrain and optimization of the AGVs control variables. Therefore, the drawbar pull performance of a prototype AGV was evaluated in a soil bin at varying slopes, speeds, and drawbar pull (DP). The AGV’s traction performance was expressed in three metrics: tractive efficiency (TE), travel reduction ratio (TRR), and power number (PN). Optimizing the control variables is intricate and ill-defined, which requires an accurate model to predict the performance of the proposed multi-AGV system. Hence, this study aims to design an artificial neural network (ANN) to estimate the traction behavior of the AGV on a sloped testbed as a function of AGV’s speed, applied DP, and slope. A multi-layer perceptron feed-forward ANN architecture with a single hidden layer trained with a back-propagation algorithm was adopted. A series of ANN models with increasing complexity and different hidden layer activation functions were developed for each response variable, i.e., ANN-TE, ANN-TRR, and ANN-PN. A re-sampling-based method, K-fold cross-validation, was employed to estimate the model generalization error. The model success was evaluated via Mean Squared Error (MSE) and the Coefficient of Determination ( R 2 ) against a test set. The final predictive model was trained on the entire data set, and the observed R 2 was 0.933, 0.882 and 0.858, respectively, for ANN-TE, ANN-TRR, and ANN-PN. Subsequently, a Monte-Carlo Simulation based uncertainty analysis was carried out to demonstrate the model strength and the degree of uncertainty by constructing a 95% prediction interval. This study shows ANN as a promising, robust, and reliable method to predict traction performance in agricultural tillage-traction studies and developed models can empower the multi-AGV system on steep-uneven slope terrain.

Energy performance of farm tractor with single radial versus dual diagonal wheels in harrowing operations

ABSTRACT The farm tractor wheel interacts directly with the soil, affecting its energy and operational performance. Several works study the particularities between configurations of wheelset seeking to interpret the most efficient type and arrangement of the wheelset. However, there is still a demand for studies that elucidate decision-making regarding changing the type of wheelset or improving the pre-existing arrangement. The experiment aimed to evaluate the energy performance of farm tractors equipped with Single radial and Dual diagonal wheels in rear axle in intermediate harrowing operation. The experiment was conducted in a randomized block design. Two-wheel arrangements (Single radial and Dual diagonal) were used in the blocks, and four target velocities (4, 6, 8, and 10 km h-1), with four replicates in the subblocks, totalizing 32 experimental units. Slip of wheels, engine rotation, hourly and specific fuel consumption, force, power, and efficiency in the drawbar, operational velocity, and engine thermal efficiency were monitored. The data collected were submitted to analysis of variance and, when significant, to the Tukey test and regression analysis. The Single radial tires provided an increase in velocity and drawbar force without increasing fuel consumption, consequently providing an increase in energy and operating performance in intermediate harrowing operation.

ПРИМЕНЕНИЕ ШИН УВЕЛИЧЕННОЙ РАЗМЕРНОСТИ, КАК СПОСОБ ПОВЫШЕНИЯ ЭФФЕКТИВНОСТИ РАБОТЫ МАШИННО-ТРАКТОРНОГО АГРЕГАТА

It is known that one of the most effective ways to improve the traction performance of wheeled vehicles is to increase the area of contact between the propeller and the supporting surface. The performance indicators from the use of tires of increased dimension are presented, by reducing the level of unproductive losses for self-movement, slipping and processing of over-compacted soil along the tire track. The results of comparative assessments of traction and operational and technological indicators of the T-150K tractor on plowing with serial tires of dimension 21.3R24 and tires 66x43R25 with DW36x25 disks are presented. As a result of the study, an increase in the traction efficiency of the tractor on a stubble background by 11 - 44.5% was obtained. An increase of 1.36 times in the traction force developed by the tractor compared to the serial version with a slipping level of 15% was obtained. Comparative evaluation of performance indicators found that when working with a 5-furrow plow, the performance of the unit with 66x43R25 tires was 40% higher than that of the serial sample, and per hectare fuel consumption was 38% lower. When working with a 4-furrow plow, the differences in productivity by options amounted to 36%, and specific fuel consumption - 32%.

Determining the influence of geometric parameters of the traction-transportation vehicle's frame on its tractive capacity and energy indicators

This paper reports results of studying the influence of geometrical parameters of the frame in a traction-transportation vehicle on its traction and energy indicators. A method for estimating the influence of geometrical parameters of the frame in a traction-transportation vehicle on its traction and energy indicators has been substantiated, based on the traction calculation of the tractor and taking into consideration the change in the distance from the hinge of the traction-transportation vehicle to the front and rear drive axles. The method makes it possible to determine the normal reactions, tangent thrust forces, and traction power on the wheels of the machine. The method reported here enables defining the optimal geometric parameters for improving the traction-adhesion and fuel-economic indicators of the traction-transportation vehicle. It was theoretically established that the normal reactions on the front wheels of the studied traction-transportation vehicle are 27,800 N and exceed by 1.95 times the normal reactions on the rear wheels of 14,200 N. This is due to the fact that the distance from the hinge to the corresponding axles of the wheels is 1.89 m and 0.97 m. Increasing the distance from the hinge to the axle of the rear wheels to 1.17 m produces a positive effect on improving the tractive performance of the traction-transportation vehicle. There is an increase in the tractive power on rear wheels to 24.39 kW. The experimental study of the traction-transportation vehicle was performed using an all-wheel-drive machine with a hinge-connected frame as an example. The maximum traction power is 121 kW, which is achieved at a speed of 12 km/h, traction efficiency of 0.68, and a thrust force per hook of 30.2 kN. The difference between the results obtained theoretically and experimentally is 8 %. Applying the method could make it possible to provide designers and manufacturers with recommendations for the construction and improvement of a traction-transportation vehicle, to improve traction and adhesion properties, and reduce the anthropogenic impact on the soil

Traction Performance Estimation of Lunar/Planetary Rover Wheel Using Finite Element Modeling

Finite Element Analysis is the process of simulating the behavior of a part or assembly under given conditions so it can be assessed using the finite element method (FEM). A finite element model is developed using commercial and widely available software Abaqus/Explicit 2020. The core objective of this research is to perform finite element analysis to predict traction performance of wheel on lunar/planet soil. In this research, Soil is modelled with parameters that represent pressure-dependent elastic-cap hardening. Drucker-Prager/Plastic law is followed. Mesh independence study is done to obtain results with finer mesh. Displacement magnitude, Equivalent Plastic Strain (PEEQ) and Slip are analyzed.

A multi-sphere DE-FE method for traveling analysis of an off-road pneumatic tire on irregular gravel terrain

In recent decades, extensive effort has been devoted to simulating the tractive performance of an off-road tire on granular terrain using the combined discrete element and finite element (DE-FE) method. Previous works normally idealized irregular gravel materials using spherical DEs, requiring an artificial rolling resistance moment to deal with the interlocking mechanism between irregular granular particles. In this work, we propose a multi-sphere DE-FE method to address this issue. The main appeal is that our presented method can describe the irregular shapes of gravel materials more accurately, and simulates the interactions between non-spherical granular particles and the tire in a natural way. As a result, the artificial rolling resistance moment is not required in our presented method. Three kinds of multi-sphere gravel particle models are established, and the effectiveness of our proposed method is validated via a piling test. Then we calibrate the simulation parameters of tire-terrain interactions using triaxial tests. Finally, the generation method of the multi-sphere gravel terrain is presented, and the tractive performance of an off-road pneumatic tire on irregular gravel terrain is simulated. Our simulation results are found to be in good agreement with experimental data. Numerical results also show that our presented method can better reproduce the traveling behavior of the tire than the widely used spherical DE-FE method in terms of the tractive force and rim sinkage histories.

Enhancing the tractive performance of unmanned vehicles using an optimised wheel-step driving system

A wheel-step driving system that can realise a wheel-step driving mode is proposed to improve the tractive performances of wheeled unmanned vehicles when driving on soft roads. Although the wheel-step driving system proposed in this paper adopts double wishbone suspension, it also can be applied for different suspension configurations after adjustment. In this paper, a typical sandy soil and a designated tyre are selected as hypotheses to verify the enhanced effect of wheel-step driving system on tractive performance. First, the wheel-soil interaction mechanism of the wheel-step driving mode is analysed based on terramechanics theory and the wheel-step driving strategy is optimised. The tractive performances of the wheel-step driving mode and the normal driving mode are compared and analysed through numerical calculations. Then, a soil model is established using discrete element software and a wheel model is established using dynamics software; the coupled simulation of the dynamic and discrete elements compares the drawbar pull, the driving torque and the sinkage in the normal driving mode, the wheel-step driving mode and the optimised wheel-step driving mode. The simulation data verify the effectiveness of the optimisation strategy used and the enhancement effect of the wheel-step driving mode on the traction performance. Finally, a soil-bin test system is built and a tractive performance experiment is performed. The experimental data and the simulation data show good agreement, thus verifying the correctness of the simulation model.

Fatigue Analysis of Spike Segment of Special Tractor Wheels in Terms of Design Improvement for Chernozem Soil

The driving wheels affect the tractive efficiency, fuel consumption, and soil compaction. This study presents the fatigue analysis of a spike segment that is the main part of an innovative driving wheels designed to improve tractor tractive performance. The design improvement was proposed for Chernozem soil allowing the full penetration of spikes. The spike segment was loaded by forces resulting from the maximum drawbar pull at 100% wheel slip and penetrometer resistance. A drawbar pull increase caused by the spike tires was also calculated. The experiments were performed using a subcompact tractor in the first gear on a grass field at soil moisture 18.8%. Gerber theory was used for the fatigue analysis performed using ANSYS software. The dependances of the safety factor on the horizontal rod diameter and the number of load cycles was constructed. The safety factor of 1.73 calculated for the spike segment made of steel S355 is suitable for the reduction of the actual horizontal rod diameter (12 mm). The fatigue analysis showed a safety factor of 1.28 at 100,000 load cycles in the case of a reduced diameter (10 mm). A diameter of 8 mm was also simulated, but the calculated safety factors do not allow it in terms of safe operation.

Simulation-Based Comparative Assessment of a Multi-Speed Transmission for an E-Retrofitted Heavy-Duty Truck

Electric retrofitting (e-retrofitting) is a viable option for accelerating the renewal of heavy-duty vehicle fleets to reduce the related emissions. We introduce a simulation-based assessment of e-retrofitting strategies for heavy-duty vehicles. Our simulation tool, an electric vehicle fleet simulation toolbox, comprises three modules, namely driving cycles, vehicle dynamics, and vehicle profiles. The first allows for the creation of realistic driving cycles based on GPS data from real routes. The vehicle dynamics and vehicle profiles incorporate, e.g., the modelling of the powertrain and driving conditions. Ten realistic driving cycles were created and used for investigating and comparing three different powertrain alternatives, including the original diesel powertrain, electric with a single-speed transmission and electric with a multi-speed transmission. The vehicles were simulated in two different heavy-load scenarios. First, driving with a cargo load represented by the maximum vehicle weight and second, driving with snow ploughing. We found that the multi-speed transmission in an electric heavy-duty truck significantly improved its traction performance and gradeability. On the other hand, the effect on the electric powertrain efficiency, and thereby on the energy consumption, remained rather minor. Considering the given workload scenarios, our results advocate employing rather than omitting the gearbox in the e-retrofit truck process.

Energy Saving Performance of Agricultural Tractor Equipped with Mechanic-Electronic-Hydraulic Powertrain System

Tractors are usually applied in field operations, road transport, and other operations. Modern agriculture has higher design requirements for tractor powertrains due to the complicated working environments and various operations. To meet the driving requirements of the tractor under multiple operations, a mechanic-electronic-hydraulic powertrain system (MEH-PS) for tractors has been designed according to the characteristics of the hydro-mechanical composite transmission and electromechanical hybrid system. The principle of multiple driven and transmission modes of MEH-PS are introduced, the speed regulation characteristic curve of hydro-mechanical transmission (HMT) is given, and the related power element model, tractor model, and efficiency model are established. The HMT optimal economy transmission ratio control strategy and hybrid rule-based optimization energy management strategy were developed. Take three typical tractor operations for analysis: ploughing, harvesting, and transport. The results show that the engine operating points are mainly distributed in the higher load area, the tractor maintains high system efficiency, and the relative error between simulated and tested fuel consumption is within 5%, which further proves the reliability of the model. The solution also showed lower fuel consumption in all three operations compared to DLG’s announced PowerShift tractors and CVT tractors. Thus, the powertrain system can meet the tractor’s drive requirements under complex operating conditions and maintain high efficiency and is therefore suitable for tractors that need to operate frequently in the field and on the road.