Track Rollers Research Articles

Dynamic Contact Characteristics Analysis of Heavy-duty Track Rollers

As an important component of the crawler walking device, the track roller needs to withstand strong impact and is prone to failure, which can lead to serious economic losses. This paper focuses on the track roller of the spreader as the research subject and investigates the dynamic contact characteristics between the track roller and the track plate. Using RecurDyn software, a virtual prototype model of the crawler walking device is established to analyze the variation in a vertical dynamic load of the track roller under different working conditions. Simultaneously, a finite element model of the contact between the track roller and the track plate is developed using Ansys Workbench, and its accuracy is verified using Hertz contact theory. Finally, the study discusses various influencing factors on the contact characteristics, including load, curvature of the contacting bodies, and material yield strength. The results indicate that the track rollers experience the highest dynamic load when climbing a slope, reaching a maximum load of 1191.44 kN. Moreover, the maximum contact stress is 1750.4 MPa, and the maximum Mises stress is 921.34 MPa during this operation. Importantly, when the load reaches 1218 kN, the maximum Mises stress of the track roller is 930.2 MPa, which may lead to roller failure after prolonged use. These findings provide valuable insights for the design and optimization of heavy-duty track rollers and offer significant assistance for various tracked vehicles.

Применение канатно-рельсовых дорог для трелевки сортиментов

The article presents constraining factors of the use of traditional approaches for timber skidding in the winter logging period in the North-West Federal District of the Russian Federation. Based on the study of scientific literature, the classification of cable-railways is given, methods of fastening the platform or cable car to the traction cable, the peculiarities of cable selection are considered. The modes of operation of cable-railways are described (without an engine – as a timber slide, with an engine without a trailing cable, with an engine with a trailing cable), the basic requirements for cable-railways and factors limiting the scope of application of such roads are considered. A methodology for determining the driving forces is proposed. It takes into account the weight of the car moving on the slope, the number of cars, the angle of inclination of the track section, the resistance to car movement, additional resistance to car movement when passing curves, the weight of the cable, its length, the friction of the cable on the ground, sleepers and other obstacles, which depends on the condition of the track structure, the density of sleeper laying, ballast protruding on the surface, cable lubrication and other factors. In addition to the above, power losses from the resistance of track rollers when they are enveloped by the running down branch of the cable, friction losses in the trunnions of the winch drums and friction losses from the cable enveloping the winch drums were considered. The article discusses the conditions under which it is possible to move the car down the slope, as well as prevent slipping and provide cable braking in the grooves of the drums. Limitations for the use of cable-railways, depending on the nature of the track, rolling stock, slope angle of the track, average skidding distance, are determined. A technical solution to improve the existing cable-railways using an articulated carriage that increases the operational properties of cable-railways, is proposed. The proposed design allows to reduce the wear of cables and to organize timber harvesting, including on nonstraight skidding trails with rotation angles up to 45 degrees. At the same time, the design of the articulated carriage can be effectively applied on cable-railways already in operation. For citation: Svoykin F.V., Svoykin V.F., Sokolova V.A., Voinash S.A., Ariko S.Ye. Application of Cable-Railways for Timber Skidding. Lesnoy Zhurnal = Russian Forestry Journal, 2023, no. 5, pp. 115–125. (In Russ.). https://doi.org/10.37482/0536-1036-2023-5-115-125

Моделирование динамики промышленного трактора при низкочастотном вибровозбуждении со стороны гусеничного движителя

The article is devoted to the development of a mathematical model of an industrial tractor with a semi – rigid suspension. The model is intended for the computational study of vibrations at the driver's seat caused by low – frequency impact from the caterpillar mover. A review of wel l–known mathematical models describing the dynamics of the system “soil – caterpillar mover – tractor body – cabin – vibration protection seat – driver” is made. Various methods of soil modeling and tractor caterpillars are considered. It is proposed to use the ANSYS Motion software package to simulate the subsystem "soil – caterpillar – track rollers – bogie". The model describes in detail the undercarriage system, taking into account the actual geometry of the tracks, the arrangement of the track rollers, as well as other design features. To describe the deformation of the soil in the software package, are used the relations by Becker and Wong. The article presents the results of modeling the dynamics of the tracked bogie of the industrial tractor T–130 of the Chelyabinsk Tractor Plant when moving on deformable soil. Calculations were made for three types of soil and for different locations of road wheels. The processes of vertical and angular displacements of the bogie are obtained. An analysis of the calculation results showed that the proposed model reveals the influence of soil properties and the design of the running system on the vibrations of a moving tractor. The processes obtained as a result of the simulation will be used as an input for the model describing the subsystem “tractor body – cab – vibration protection seat – driver”. The model will be used for computational studies when optimizing the vibration protection of the tractor operator. Recommendations will be developed to change the arrangement of the road wheels and the elastic–damping characteristics of the vibration protection elements to minimize the vibration impact on the tractor operator

Исследование влияния параметров гидропневмоаккумулятора на работу устройства управления положением цилиндрической щётки коммунальной машины

The article is devoted to the actual problem of improving the quality of cleaning roads and sidewalks by communal machines with brush working equipment. One of the main parameters of the working process of a communal machine with brush working equipment, which determines the cleaning efficiency and brush life, is the brush pressing force against the surface to be cleaned. In order to ensure the highest efficiency of the cleaning process during the operation of the communal machine, it is required to maintain a certain value of the brush pressing force. During the operation of a communal machine equipped with brush implements with track rollers, the pressing force can vary significantly. To maintain the required value of the brush pressing force against the surface to be cleaned, a device for controlling the position of the brush working equipment using a hydropneumatic accumulator connected to the rod end of a standard hydraulic cylinder is proposed. The pressure of the working fluid created by the hydropneumatic accumulator and acting on the piston of the hydraulic cylinder creates a force acting on the brush working equipment, which makes it possible to provide the necessary force for pressing the brush to the surface to be cleaned. The performance indicators of the device for controlling the position of the brush working equipment depend on the selected values of the design parameters of its elements, including the parameters of the hydropneumatic accumulator. The dependences of the deviation of the brush pressing force from the required value during the vertical movement of the brush working equipment on the useful volume, the initial charging pressure and the maximum pressure of the hydropneumatic accumulator are obtained. A method is considered to reduce the deviation of the brush pressing force from the required value by connecting an additional volume to the gas cavity of the hydropneumatic accumulator.

Introducing an Open-Source Simulation Model for Track Rollers Considering Friction

Locating bearing track rollers are used, for example, in monorail transport systems to enable relative movement between the rail and the shuttle. Due to the two-point contact, both radial and axial forces can be transmitted simultaneously. Since friction is involved, the state of the art does not provide any calculation rules for the dimensioning and design. The development of a calculation model with sophisticated commercial software brings its difficulties since no plausibility check is possible using existing models. For this reason, a model based on analytical descriptions including the Hertzian and the elastic half space theories is presented in this paper. It bridges the gap between very simple approaches and widely developed commercial software. With this model, the contact forces, friction forces, surface tensions, relative velocities and subsurface stresses can be calculated for both free and driven rolling. The main advantages are that the model is easy to apply, and thus comparisons between different track roller designs can be made quickly.

Loose blasting of rocks at quarries of the Petropavlovsk group ofcompanies

At present, in most quarries of the Petropavlovsk group of companies, mining is carried out using  hydraulic excavators with bucket capacity up to 18 m3. Hydraulic excavators have mass three times lessthan the mass of mechanical shovels, therefore, given large scooping forces, they lose stability during operation and rotate relative to the front track rollers. The loss of stability complicates operation of excavators and requires fine crushing of rocks by blasting, which forces the increased powder factor, i.e. the increased material costs. In mines of the Petropavlovsk group of companies, experts of AVT-Amur LLC conducted the research aimed at essential increase in delay intervals up to 300 ms. The extended delay intervals during downhole blasting make it possible to increase the total duration of repeated alternating loads on rock mass, including the tensile stresses. The delay of 150 ms or more allows each blast to be directed not toward incipient cracks as with delays of 40–80 ms, but toward the free surface of ope n cracks, which provides a blasting muck pile almost within the limits of the block at minimal scatter of rocks and at the same fragmentation quality. The long-term use of the extended delay intervals of AVT-Amur LLC in mines proves the high quality of fragmentation of rocks by blasting at zero scatter, which enables approach of dump trucks to the block immediately after blasting, without cleanup. Experimental explosions show that blasting with long delays allows an increase in the yield of blasted rocks by 35% at the powder factor reduction by 21%.

Analysis and Optimization of Static Contact Characteristics of Heavy-Duty Tracked Vehicle Rollers

The static contact characteristics of heavy-duty tracked vehicle roller and track plate contact structure are analyzed, and the influence mechanism of the roller’s shape parameters on the contact stress is studied. According to the Hertz contact theory, a mathematical model of the roller and track plate contact is established. The contact structure model is established in ANSYS software, and the simulation results are compared with the Hertz theory results to verify each other. In the parameter optimization section for the roller and track plate, based on the Hertz stress calculation formula, a new method is proposed to establish a roller and track plate Kriging model and to globally optimize the model by the genetic algorithm (GA). After that, the relationship among the track roller radius R 1 , the track roller rim radius r 1 , and the track plate rim radius r 2 is analyzed. The results show that the difference between the radius of the rim of the roller and the track plate and the radius of the roller rim both affect the maximum contact stress. Changing the plane contact into the curved surface contact can reduce the maximum contact stress by 33%. This study can provide a reference for the design and manufacture of supporting track rollers and track plates.

Vibration analysis of agricultural machinery induced by crawler lug during on-road running

Rubber crawlers are used in a combine harvester for paddy field in Japan to ensure running performance like traction on soft ground surface and to protect a pavement road. These crawlers have relatively high lugs, and when traveling on a paved road, the lug and road surface contact with each other and to generate vibration. The structure of crawler system is more complicated than that of tires, and the mechanism of running vibration generation is not solved enough. In this paper, exciting forces related to the lug is measured first, and clarify that inputs characteristic for the track rollers, sprocket, carrier roller, and idler. Second, transfer path analysis shows contribution of the input. In addition, generalized forces are inputted in a rigid two-degree-of-freedom model and reference vibration values are calculated.

Soil compaction management: Reduce soil compaction using a chain-track tractor

Modern agricultural production requires research for new design and layout plans of the track-chained mover, providing a reduction in soil compaction. One of many ways to improve the efficiency of machine-tractor aggregate (MTA) use is to improve the geometry of the support part of the chain-track tractor. Flat geometry of the support part of a chain-track tractor with a semi-rigid suspension creates maximum pressure on soil with the first and last track rollers, which causes increased soil compaction. Research objective is to ensure the uniform pressure on soil from the tractor with a semi-rigid suspension by justifying the geometry of the supporting part of the track-chained mover.Based on experimental and theoretical studies a model of pressure distribution along the length of the support part was developed. Thus, the geometry of the support part of a track-chained tractor with a semi-rigid suspension was substantiated. Pressure decrease on soil and compaction reduction are achieved by changing the geometry of the support part and rational location of the tractor mass center. To achieve the elliptical geometry of the support part of a track-chained tractor with a semi-rigid suspension lower track rollers were placed at different heights.To test the formulas and to study the influence of the support part geometry, of the hitch height and the force on the hook of a track-chained tractor on soil compaction, experiments were conducted. As a model for experiment, the tractor actively used in agriculture was modernized; chain-track tractor T-170M1.03-55 with flat and elliptical caterpillar bypasses. The pressure was measured directly by pressure sensors that were placed into the ground. Soil density in the track left by a track-chained tractor mainly depends on mover pressure and the number of impacts per pass. Track-chained mover makes two impacts on soil with the flat support part. If the support part geometry is changed, the number of impacts on soil is reduced to one. To create typical working conditions for T-170M1.03-55 track-chained tractor the third and fourth support rollers should be lowered by 9.5 ± 1.5 mm, the second and fifth-by 4.5 ± 0.5 mm relatively, which leads to a decrease in the maximum pressure on soil and reduces its compaction in the track left by the mover by 15–25%.

Calculation of the efficiency of the planetary gear K-V-V without a carrier

The work is dedicated to the calculation and improvement of the efficiency of the novel planetary gears without a carrier. The feature of the K-V-V gears is the misalignment of the axles of the driving wheel, the driven wheel and the supporting wheel. Three types of the gearing are considered: 1) involute; 2) involute with the track rollers; 3) articulated. Calculated values of efficiency at characteristic gear ratios are higher than, for example, worm gears, especially for variants with support rollers and gear-hinge gears. The articulated gear (variant 3) is much simpler than the involute gear with the track rollers (variant 2).

Fatigue strength assessment of track rollers

The paper presents a general concept for fatigue strength assessment in rolling contact between track roller and rail. The multi-axial stress state is analysed using the critical plane method. Depending on the orientation of the section plane, different load cycle combinations result with different stress-amplitude and mean-stress combinations. The Haigh diagram outlines the fatigue strength of the material. The load cycles in all section planes are plotted there and the safety factor can be determined directly. In comparison to other empirical concepts, similar values are obtained for the allowable maximum contact pressure. The advantage of this method is its general applicability, without any restrictions regarding the geometry or material.

Prospects for the development of undercarriage systems of modern mobile energy devices for agricultural purposes

The final stage of the cultivation of crops is harvesting. The quality of the operation depends on the annual result of the effectiveness of all previous work. It is important not only to harvest well, but to preserve the fertility of the soil and avoid soil compaction. The problem of compression is becoming more acute due to the massive use of heavy wheeled tractors and combines. The degree of soil compaction depends on the type of propulsion unit, the weight of the tractor and the number of passes of the units across the field. The negative impact of undercarriage systems on the soil should be considered when creating new machines based on new layout schemes, to reduce the structural weight, taking into account the dynamics and distribution of the center of mass of the variation in hook load. To reduce pressure and evenly distribute it is possible through the creation of more advanced propulsion and suspension systems. The purpose of this article is to analyze the most promising designs of the mobile agricultural machinery undercarriage systems, which can reduce the specific pressure on the ground, improve the throughput of agricultural machinery and provide a more comfortable planting and harvesting. At the moment, the following main directions of development of agricultural machinery undercarriage systems can be distinguished: pneumatic tracks, twin wheels, half-track, installation of rubber-reinforced tracks (RRT) and torsion as an elastic suspension element. The tests carried out confirmed that the installation of a changeable tracked propulsion unit can reduce the degree of soil compaction by 17-46 %, and the use of twin wheels showed an increase in pulling force by 20 % and a decrease in gauge depth by 40 %. The use of pneumatic trackers allows to increase the permeability of the transport vehicle on soils with a weak bearing capacity and at the same time minimize the damage that it can cause to the supporting base. Recently it is popular to operate the agricultural machinery, which uses rubber-reinforced caterpillar. Its caterpillar operational cycle if higher of 4-5 times comparing to those from metal. In addition, it allows to reduce vibration load and do the work at wet soil conditions. RRT is put both in the all-track version, and in the form of a wheel-caterpillar. This propulsion unit has a triangular shape of rubber tracks is mounted instead of wheels. Currently, individual torsion hangers of track rollers are widely used on tracked tractors. The advantages of the new torsion-balance suspension made it possible to increase the reliability and durability of tracked tractors undercarriage systems.

Совершенствование системы виброзащиты операторов промышленных тракторов

When developing new models of industrial tractors, compliance with the regulatory requirements for vibration protection of operators is verified at the stage of certification tests. At this stage, development procedures are associated with significant time and material costs. The article proves the possibility to use a computational and experimental technique which allows us to determine the level and frequency content of potentially dangerous vibration sources at the deve­lopment stage; to develop computer models of the system “excitation source – frame – cab – antivibration seat – operator”; to develop proposals to comply with legislative requirements using parametric forecasting. As an example, the problem of vibration in the low frequency range of 2–14 Hz was considered. This vibration is caused by rolling of track rollers on the track chain, which lies on a yielding soil foundation. Basing on the analysis of field test results, the kinematic effect of track rollers on the tractor frame was represented as stationary random narrow-band processes. A mathematical model of the tractor was described by a set of differential equations with random input processes. Methods of statistical dynamics were used to implement the model. The simulation data of T-11 motion with different speeds are given. The results are presented as a set of transfer functions, as well as the spectral densities of changes in generalized model coordinates and accelerations at the driver’s seat. The difference between the calculation results and the experimental data does not exceed 15–20 %. The effect of elastic-viscous characteristics of vibration protection devices on the level of accelerations at the operator’s seat was analyzed. As a result, it was recommended that these characteristics should be changed in order to reduce the vertical vibration acceleration of the driver’s seat. This approach allows us to solve the problems of vibration protection of operators when designing and testing prototype models of road-building machinery. It is achieved by tuning out the system “track assembly – frame – cab – antivibration seat” of resonance phenomena.

Расчетная оценка возможности применения подшипников скольжения из пористого стеклопластика в составе опорного катка гусеничного движителя

Currently, antifriction bushings for sliding bearings made of expensive non-ferrous metal alloys are used in low-speed caterpillar track rollers. Composite bushings based on porous GFRP obtained by radial winding is a cheap alternative for metal ones. They can withstand high radial compressive loads and successfully work without lubrication supply system using only selflubricating modifiers in their open porosity. The bushings have a low stiffness in the radial direction due to the porous structure. Low stiffness contributes to the formation of a significant contact area between interacting surfaces. Low contact normal and tangential stresses lead to a shaft wear reduction. Low interlaminar strength is the main factor limiting the use of composite bushings. Determination of the maximum radial and shear stresses emerging in the operational process of a friction unit is a very important problem. First part of the work is devoted to determination of the static and sliding friction coefficients for composite bushing. Combination of static tests up to fracture and numerical analysis was used to determine the critical interlayer shear stress. In the second part of the work, numerical model of a support roller with antifriction bushing was developed. This model was used to determine the stress-strain state of antifriction bushings of the support roller of pipe-laying machine TR-20. Distribution of normal stresses on the contact surface with the shaft for GFRP and bronze bushings were found. The relations between the maximum normal stress value and the radial clearance in pair “shaft-bushings” were obtained for both types of bushings. It was shown, that the value of the local normal stresses is significantly affected by the skew-symmetry of the roller support, clearance in pair “shaft-bushings” after assembly and after exploitation. The maximum reasonable value of the radial clearance between the shaft and the bronze and GFRP bushings were0.25 mm and 1 mm respectively. The use of antifriction composite bushings allows increasing the value of the maximum permissible clearance of friction unit more than two times in comparison with metal one. The paper shows the possibility of replacing antifriction bronze bushings on porous GFRP bushings.

Simulation of the formation of vibration loading of operator workplace of industrial tractor

The check of compliance with legislative requirements for vibration protection of operators is carried out at the stage of certification testing of new and upgrading products. At this stage, the further development is associated with high time and material costs. The article substantiates the possibility of use of a calculation and experimental method which allows to determine at the development stage the level and frequency content of potentially dangerous sources of vibration; to develop a computer model for the system «excitation source - frame - cab - antivibration seat - operator»; to make out proposals to comply with legislative requirements by means of parametric forecasting. As an example, the problem of vibration in the low frequency range of 2-14 Hz is considered. This vibration is the result of the process of rolling of track rollers on track chain that lies on the yieldable soil foundation. According to biomedical research, the resonance frequencies of critical parts of human body are in this low frequency range, which is displayed in sanitary norms. Based on the analysis of field test results, the kinematic impact of track rollers on tractor frame is represented as stationary narrow-band random processes. Mathematical model of the system is described by a set of differential equations with random input processes. The methods of statistical dynamics are used to implement the model. The simulation results are presented as a set of transfer functions. They represent the distribution of resonance frequencies of angular and heave oscillations of the separate system elements and the spectral density functions. These results allow to obtain the quantitative estimations in the form of mean-square values of the output processes. The use of this approach allows to solve the problems of vibration protection of operator at the stages of design and testing of prototypes of road-building machinery. It is achieved by tuning-out of the system «track assembly - frame - cab - antivibration seat» from resonance phenomena and by introducing some design solutions.

Stabilization of thermal stress in tires of vehicle track rollers

The article provides a rationale method for stabilizing thermal stress in tires of vehicles track rollers by choosing the angle of suspension unit setting.

Prediction and Evaluation of Vibration Characteristics of an Agricultural Rubber Crawler Vehicle Equipped with Movable Track Rollers

Prediction and Evaluation of Vibration Characteristics of an Agricultural Rubber Crawler Vehicle Equipped with Movable Track Rollers

Evaluation of the efficiency of systems to reduce vibration on modern tracklaying tractors

Agricultural operators run a very high risk of exposure to mechanical vibration. To improve comfort, many different devices have recently been fitted to agricultural self-propelled machinery, especially on the most modern high-powered wheeled tractors. In contrast, agricultural tracklaying tractors are not equipped with a suspended cab floor and frequently poor or no seat suspension is fitted. Consequently, the levels of vibration measured in the driving seat of tracklaying tractors often widely exceed the limit stipulated by official national standards. The manufacturers of tracklaying tractors are currently trying to improve the level of comfort at the driver’s place by reducing both the production and the transmission of vibration. The vibration levels at the driving seat of a group of tracklaying tractors produced by some leading Italian manufacturers were so measured. The models examined in the study differed in having either 5- or 6-roller track support, different types and stiffness of seat suspension, and in whether or not they were coupled to an implement. The type of seat suspension, and above all its correct adjustment, dramatically influenced the level of vibration, as did the increase in the number of track rollers. In contrast, whether or not the tractor was coupled to an implement at the rear 3-point linkage did not make any significant change to the vibration comfort during transport. Also on the best modern trackalying tractor models, vibration levels frequently exceed stipulated limits, so that a further reduction is urgently required. Possible solutions that could be developed may involve the universal adoption of rubber tracks and/or the fitting of silent blocks on the cab floor and suspension devices on one or both axles.

Numerical Simulation of Fatigue Crack Growth of New-Material Track Rollers

Because of the excellent mechanical properties of Austempered Ductile Iron (ADI), track rollers can be made out of this material. The casting may lead to cracks forming inside rollers and there will also be some scratches in the surface when rollers work, which will greatly affect the lifespan of rollers. It is helpful to use crack propagation method based on the Finite Element Method (FEM) to simulate the crack growth. Firstly, define the position and the value of the force imposed on rollers. If the load is compressive, contact pairs should be set between the crack surfaces. After the model is established, Stress Intensity Factors (SIF) KI and KII can be calculated with the node displacement theory by using the commands of FEM software. With the maximum principal stress theory, crack growth direction can be determined. Since the values of KI and KII calculated by the software are positive, we should judge weather the values are positive or negative to get a right propagating angle. The analysis applies linear elastic fracture mechanics and FEM modeling the crack propagation in the elastic state.

Prediction of the vibration characteristics of half-track tractor considering a three-dimensional dynamic model

A dynamic three-dimensional model was constructed for a half-track tractor that considers its bounce, pitch, and roll motions in order to clarify the tractor’s vibration characteristics. Driving experiments were conducted in which the tractor was driven on a solid asphalt road surface in order to investigate its vibration characteristics and to verify the validity of an analysis based on motion equations that were formulated from the proposed dynamic model. The experiments were conducted with a half-track tractor apparatus equipped with twelve accelerometers for the measurement of 6 DOF of acceleration of the tractor’s centre of gravity. The discrete time series of the measured data was resolved and reconstructed by wavelet analysis. The model was verified using the fixed lug phase difference between the left and the right crawler systems for each combination of three location arrangements of the track rollers and seven levels of tractor speed. Results showed that the acceleration of the centre of gravity for the bounce, pitch, and roll motions was at a minimum when the track rollers were set equidistant from one another. The acceleration caused by the bounce and pitch motions decreased with an increase in the lug phase difference, while the acceleration caused by the roll motion increased with an increase in the lug phase difference. The results further suggested that the proposed three-dimensional dynamic model could be improved by incorporating into it the lug phase differences that change during actual tractor driving, instead of a constant lug phase difference.