Crawler Tractor Research Articles

Material and technical base of agriculture: availability of tractors and the state of tractor construction

One of the main factors affecting the efficiency of agricultural production, timing and quality of agricultural work is the availability of equipment. Among all the variety of agricultural machines, tractors are of key importance. The measures taken by the state to support technical modernization contribute to the partial renewal of the tractor fleet of agricultural organizations, but do not allow to stop the process of its reduction. The existing volumes of purchasing tractors are not enough to radically change the situation. The fleet of agricultural tractors continues to decrease and along with it, the indicators of tractor availability are decreasing, which negatively affects the quality and timing of agricultural work. In terms of availability of agricultural tractors, Russia lags far behind the majority of both developed and developing countries in the world. The growing load on tractors and their high average age lead to violations of agricultural deadlines, increased downtime of equipment, additional material and technical costs for repairs, increased consumption of fuel and lubricants, seeds, fertilizers, etc. In the domestic tractor industry, a difficult situation also remains. The existing nomenclature and production volumes of domestic tractor-building enterprises do not allow to meet the needs of agriculture. There is practically no production of crawler tractors, specialized tractors for gardening and viticulture. In this regard, there is a high dependence on the supply of imported tractors. Despite the significant decline in machinery output in recent years, the Republic of Belarus remains a leader in the production and import of agricultural tractors to Russia and the CIS countries.

The residual stand damages due to log skidding using crawler tractor at one logging company in Central Kalimantan

An investigation on residual stand damages due to log skidding using a skidding tractor was carried out at one logging company in Central Kalimantan in 2012. The objective is to find out information about residual stand damages on trees, poles, and sapling caused by Conventional Log Skidding (CLS system) and Low Impact Log Skidding (LILS system). Data on stand potency consists of tree, pole and sapling levels as well as the number of trees felled were collected. The investigation revealed that damage to the level of standing trees, poles, and sapling skidding caused by CLS system at PT Gunung Meranti was 11.40% (Coefficient of variation/CV) 7.95%; 9.53% (CV 14.74%) and 14.84% (CV 16.92%), respectively. The average damage of standing trees, poles and sapling caused by LILS system in PT Gunung Meranti respectively was 9.85% (CV 14.00%); 7.54% (CV 9.81%) and 12,55% (CV 16.60%). LILS system could reduce the damages to the standing trees.

Design and physical model experiment of an attitude adjustment device for a crawler tractor in hilly and mountainous regions

To address the problems of difficult leveling and poor stability of hill crawler tractors, an attitude adjustment device based on a parallel four-bar mechanism was designed, and the mechanical reasons for the sideslip instability of hill crawler tractors were analyzed. On this basis, a posture adjustment mechanism based on a parallel four-bar mechanism was proposed, and the structure of the complete attitude adjustment device was designed. To ensure that this device meets the strength requirements during operation, a mechanical analysis of the key components (active rocker and slave rocker) was carried out to accommodate the load during leveling. Based on ANSYS software, a finite element simulation analysis was used to determine the maximum stress position of the active and slave rockers. Finally, to verify the accuracy of the above simulation analysis results and determine the influence rules of the lateral slope angle, longitudinal slope angle and loading quality on the abovementioned maximum stress, a physical model test bench of the attitude adjustment device was built. An orthogonal regression experiment was carried out with the maximum stresses of the active and slave rockers as the test indices. The experimental data were analyzed by Design-Expert 10 software, and the results show that the order of the primary and secondary factors influencing the maximum stress of the active rocker was the loading mass, lateral slope angle and longitudinal slope angle. The order of the factors influencing the maximum stress of the slave rocker was the longitudinal slope angle, lateral slope angle and loading mass. The active and slave rockers meet the strength requirements. This work provides technical support for the production of hill crawler tractor physical prototypes.

Development and Testing of the Power Transmission System of a Crawler Electric Tractor for Greenhouses

HighlightsBuilt a functional electric drive system of a crawler tractor for greenhouses.Properly integrated the electric components into a traditional tractor.Performed field rotary tillage, field transport, and plowing energy consumption tests to verify the correctness of the matching of the core components of the power transmission system and some performance of the prototype crawler electric tractor.Abstract. Greenhouses are among the most rapidly developing sectors of the Chinese agricultural industry, and they require considerable mechanization. Currently, the machinery used in greenhouses mainly include micro cultivators powered by internal combustion engines. The micro cultivators have various problems such as small output power, low operating efficiency, and poor quality. Also, they harm the growth environment of crops and the working environment of farmers due to gas emissions and noise. In this study, a crawler electric tractor suitable for greenhouses is proposed. It can function in small working areas and narrow working spaces. The electric tractor is suitable for towing, transportation, lifting, and power output. A power transmission system scheme was designed for the electric tractor and a parameter matching method for the core components of the power transmission system is proposed. The prototype of the electric tractor was manufactured and underwent field rotary tillage, field transport, and plowing energy consumption tests. The results of rotary tillage and transportation testing showed that the operating parameters such as the depth and width of rotary tillage and transportation speed met the design requirements, which validated the matching of core components of the power transmission system and the operating performance of the prototype crawler electric tractor. The mean rotary tillage depths of the prototype on the left side and the right side are 11.0 and 12.1 cm, respectively. The mean width is 113 cm. The mean speed of rotary tillage is 4.99 km h-1. The measured speed of the prototype in the field is within the speed demand range at gears I, II, and III. According to the results of plowing energy consumption test, the mean electrical energy consumption of plowing one mu of land was 5.60 kW h mu-1, which showed that the prototype crawler electric tractor had good economic performance. To sum up, the prototype of the electric tractor for greenhouses manufactured is economic and practical. Keywords: Electric tractor, Facility agriculture, Field test, Power transmission.

Design of control system for driverless tractor

This paper uses Tianjin TieNiu crawler tractor as the experimental platform to design an unmanned agricultural machinery control system based on RTK-GPS (Differential GPS Technology). The article expounds the overall design of the control system and proposes a path tracking control algorithm. Simulation and experimental results show that the control algorithm can complete the path tracking requirements of unmanned agricultural machinery. The system can control the unmanned agricultural machinery to follow a predetermined route. The speed is 0.55m/s, the maximum error of linear path tracking of agricultural machinery is 4.09cm, the average error is 2.20cm, the maximum error of large diameter circular path tracking is 20.67cm, the average error is 8.34cm, and the maximum error of continuous small diameter turning path tracking is 23.14cm, the average error is 7.38cm, both meet the operational requirements.

Optimal weight and power parameters of crawler tractors to reduce pressure on the soil

Crawler and wheeled vehicles are used in a variety of soil and climatic conditions. In the Krasnoyarsk region crawler tractors have a number of advantages. They have a higher traction efficiency, low fuel consumption, and low pressure on the soil. Reducing the pressure on the soil helps to preserve its structure and fertility. This fact is relevant for the agro-industrial complex of Siberia. At present, the vehicle fleet of general-purpose crawler tractors is being reduced. This is due not only to economic reasons, but also the lack of justification for their operation. The paper shows the optimal weight and power parameters. The use of triangular crawler track increases traction efficiency by 3.0% and significantly expands the traction range of effective use of the tractor. For tractors of 4 and 5 classes, the optimal range of change in operating power is 140…175 kW, it corresponds to the optimal range of change in weight 8.5…9.5 tons. For tractors of 5 and 6 classes, optimal interval of changing the operating power is 155…210 kW, it corresponds to the interval of weight change 10, 5…12, 0 tons. Regulation of operating parameters is produced with a change in the coefficient of engine adaptability from 1.2 to 1.4.

Review: Bulldozer: Demolition and Clearance of the Postwar Landscape, by Francesca Russello Ammon

Francesca Russello Ammon Bulldozer: Demolition and Clearance of the Postwar Landscape New Haven, Conn.: Yale University Press, 2016, 400 pp., 70 b/w illus. $45 (cloth), ISBN 9780300200683 Narratives regarding the built environment of the post–World War II United States often emphasize the effects of clearance and the repercussions of urban, or suburban, “renewal.” In Bulldozer: Demolition and Clearance of the Postwar Landscape , Francesca Russello Ammon directs our attention to the act of clearance itself, both in the United States and abroad, focusing on the companies that benefited from demolition, the writers and artists who depicted changes on the land, and the machines that carried out the process. Ammon's protagonist in this story is the bulldozer: a powerful, relentless piece of motorized metal whose blades carved into untrammeled nature and plowed into existing urban landscapes, providing a sense of “progress” in the American imagination while exacting a staggering toll on the environment—and the mind. Friendly, smiling bulldozers may have graced the pages of several popular postwar children's books, but Ammon reminds us that the reality of demolition and clearance was not exactly the stuff of quiet bedtime reading. A wartime image of a menacing army of crawler tractors outfitted with bulldozer blades awaiting shipment to the Pacific battlefront greets the reader on Ammon's dust jacket and in the first chapter. A chilling photograph of young Presbyterian minister Bruce Klunder lying motionless after being crushed by a bulldozer during a 1964 protest against school segregation in Cleveland, Ohio, marks the book's concluding section. With some exceptions, the machines of modern renewal appear here as destructive, divisive, discriminatory, and demonic. They did not always seem so. Ammon tells a story that also underscores the pride Americans felt regarding the nation's engineering know-how and its ability to produce machines that could maneuver deftly through crumbling cities and across inhospitable landscapes, just as they did abroad during the war. She demonstrates …

The Study of Movement of the Wide Span Tractor-Based Field Machine Unit with Power Method of its Control

Abstract Recently, rapid development of controlled traffic farming convincingly demonstrates the broad prospects of using the wide span tractor-based field machines throughout the world. The issue at hand lies in the fact that having a wide span tractor-based machine with steering-wheel system moving along the tracks of a constant technological track is not a rational option. According to the concept of bridge and rutting agriculture, it is advisable to subordinate the automated means of mechanization to the principles of the functioning of the coordinate transport system in which machines can move only in two mutually perpendicular directions and for implementation of which the field must have strictly defined dimensions. Therefore, a method of power steering similar to a crawler tractor (track-type tractor) can be more efficient in the automatic driving of bridge means of mechanization within the coordinate-transport system than a kinematic control. Furthermore, methodology utilized for selection of design schemes, parameters and operating modes of machine-tractor aggregates can not be used for study of dynamics of the wide span tractor-based field machine. Theoretical study is based on theoretical mechanics, theory of mobile energy facilities, statistical dynamics and theory of automatic control of linear dynamical systems with reproduction of statistically random control and disturbing input effects. Purpose of the research lies in development of a dynamic model of plane parallel motion in the horizontal plane of a wide span tractor-based field machine unit using a power (onboard) method of control, which would allow investigation of impacts of the control parameters and disturbing influences on the controllability and stability of its motion. Mathematical models have been developed and new regularities of the straightforward parallel movement of the wide span tractor-based field machine unit for controlled traffic farming have been obtained. The results obtained allow the validation of new schemes, design parameters and modes of operation with acceptable controllability and stability of movement in the horizontal plane with a power control method of the chassis.

SOIL AERATION IS A GUARANTEE OF FOOD SECURITY FOR DESERT POPULATION

The article presents the results of the study of the method for condensation of atmospheric vaporous soil moisture. The method is aimed at improving fertility of soils, which are highly prone to desertification. For soil aeration we have developed a working tool of mole plough, which has no analogues (A.S. № 1656064). It consists of a horizontal knife in the form of parting wings. An 80 mm mole expander is located in the center of the knife, 60 mm mole expanders are located at the ends of the tool. The working tool of the mole plough is attached tightly (by welding) to the vertical knife of the mole plough. The mole plough is hung on a heavy crawler tractor. The working tool of the mole plough forms many molehills at a specified depth in the soil after a single operation and many cracks in the soil profile of vertical and horizontal directions. Due to the regular changes in atmospheric pressure in the desert, atmospheric air is constantly circulates in the molehills and cracks. Due to the difference in the temperature of “soil-atmosphere” system, atmospheric vaporous moisture condenses in the molehills and cracks of soil profile. Aeration of soils, which are prone to desertification, with the developed working tool of mole plough increases condensation of vaporous moisture by more than 23 mm/ha daily in a meter layer of soil profile during the hot season, improves biological productivity by 1.5-2 times or more. It increases the number of livestock per unit area, which ensures food security of populations in deserts.

Numerical simulation for multi‐way valves and fit clearance research based on heat–fluid–solid coupling

It is difficult to accurately calculate the working load of the multi-way valve of the crawler tractor in the traditional method. In practice, the spool and valve body are prone to over-standard leakage and clamping problems in relative movement. This study analyses the mechanism of clamp and leakage problems caused by deformation, considering the influence of gradual change of oil channel diameter and direction change in the valve body caused by the throttling of the spool. Numerical simulation of heat–fluid–solid coupling for multi-way valves is carried out. Under the condition of maximum pressure, the characteristic curve of material deformation of different spool and valve body changes with oil temperature is obtained. By evaluating the fitting characteristics of the spool and valve body of common materials, the optimal fit clearance is determined accurately. This effectively solves the contradiction between the clamping and leakage of the multi-way valve and improves the performance of the multi-way valve.

GROUND LOADING BY TRACKS OF TRACK MACHINES: REVIEW OF DESIGN SCHEMES

The results of investigations in the field of existing soil loading schemes by tracks of tracked vehicles and their effect on the traction force realized by a caterpillar propulsion device are presented. The review shows that most researchers emphasize the important role of lugs in the creation of tractive effort. However, most of the existing methods of calculating the traction force on the clutch are based on one or another specific design scheme that does not depend on the loads acting on the tracks, on the combination of the parameters of the grousers and on the physical and mechanical properties of the soil. The use of these methods does not allow us to consider the sequence and alternative variants of soil disruption, and also to establish a relationship between the magnitude of the tangential force acting on the tract with a wide range of combinations of geometric parameters of the grousers, and to link it to the physical processes taking place in the soil. Consequently, these methods do not fully describe the interaction of the crawler tracks with the ground, which makes it difficult to use them to optimize the geometric parameters of the lugs. The authors proposed an analytical method for analyzing the interaction of soil with a track of a caterpillar engine based on the regularities of the theory of the limiting state of ground masses and the main provisions used in the theory of cutting soil, taking into account the revealed features of this interaction, which makes it possible to investigate the interaction of tracks of a caterpillar propulsion with soil, taking into account the multiphase and alternative options for the destruction of soil between the grousers. This method allows you to choose the parameters of the lugs, providing an improvement in traction and coupling properties of crawler tractors.

Mechanical parameters of a constructed soil under different machinery traffic intensities in South of Brazil

Intense machinery traffic tends to degrade the soil physical quality. With the purpose of finding critical values of physical parameters and viable alternatives to minimize soil degradation, this study aimed to evaluate the effects of different traffic intensities on physical parameters of a constructed soil in Candiota, Rio Grande do Sul state, Brazil. Bulk density (Bd), porosity, saturated soil hydraulic conductivity, penetration resistance (PR) and soil compression parameters were evaluated. Different tra­ffic events (TE) were simulated during the soil construction process of an opencast coal mining area with a crawler tractor: zero (TE0), one (TE1), three (TE3), five (TE5) and eight (TE8) passes of the tractor. Immediately after the topographic recomposition and on the traffic track of the crawler tractor, disturbed and undisturbed soil samples were collected from the 0.00 to 0.10 and 0.10 to 0.20 m layers. Hydraulic conductivity, penetration resistance and soil compressibility parameters were sensitive to detect alterations in the constructed soil under different traffic events. PR values were higher than those considered as the critical limit (2000 kPa) in all layers and traffic intensities. Minimizing the traffic machinery intensities can be an effective alternative to mitigate compaction of constructed soils. More studies are necessary to obtain viable alternatives for adequate crop development in these areas.

Conceptual Design of Fertilizer Applicator for Oil Palm on Terrace Cultivation

The mechanical application of fertilizer for oil palm planted on terraces is still constrained by the narrow path which is difficult to pass by a power spreader. The objective of this research was to develop a conceptual design of fertilizer applicator for oil palm planted on terraces. The design requirements were developed based on a) terrace and track conditions, b) fertilizers and fertilization conditions, c) available prime movers, and d) user needs. Five design concepts were obtained: 1) an applicator with left and right arms to distribute the fertilizer, 2) an all-terrain vehicle equipped with a manually operated fertilizer injector, 3) an applicator equipped with a hole digger, 4) an applicator equipped with a shovel, and 5) an applicator equipped with a rotary tiller. The concepts were evaluated and compared with the current power spreader. The evaluation results showed that the applicator equipped with a rotary tiller had the most advantages on the expected criteria. The final design concept uses a 110 cm wide mini crawler tractor as the prime mover and is equipped with a hopper and a spinner disk for metering and conveying the fertilizer, and a 20 cm wide rotary tiller in the front of the machine.

SPATIAL MODELING OF TRANSPORT DEVELOPMENT OF FOREST AREA AND THEIR POTENTIAL ENVIRONMENTAL RISKS

Permanentattributesoftimberharvestingareanumberofpotentialenvironmentalrisks, eachofwhichcancausesignificantdamagetotheenvironment. The intensive development of technology and the improvement of industrial production processes have led to a significant increase in technogenic impact both on increasing catastrophic natural disasters and on the global climate change formation. The adoption of the World Environmental Constitution by all the states would be an effective means of regulating and minimizing these negative processes. Timber harvesting is one of the most dangerous types of technogenic impact on the forest environment, as the forest stand, young growth, natural watercourses and soil are damaged during logging and transportation. However, the degree of the negative impact of timber harvesting can be reduced to an ecologically acceptable level, and technical indicators of the use of timber-hauling machinery can be brought to economically feasible values by properly assessing the intensity of the environmental risk of taking a decision on certain technical and technological issues and the implementation of environmental management of this process. The article presents some approaches to the creation of GIS spatial planning model of transport development of forest-exploitation area based on the cost estimation of timber skidding considering technogenic impact of forest machines. The development of the model of forest transportation planning is a complex task. In order to solve this task, the system under investigation should be divided into separate interconnected modules, each acting as its own model: the models for forest transportation planning, the database, formulation of the task, the results of modeling, an analysis of transport movement possibilities, an analysis of environmental damage, the assessment and improvement of the existing forest road network. Concerning the proposed model and methodology that is based on the analysis of potential environmental risks associated with the rutting and cost-assessment of timber skidding, we have obtained the model map of environmentally-acceptable types of timber-hauling machines for a real forest exploitation area, the Rozhanka forest district, the Slavsk State Forestry Enterprise in particular. The proposed model makes it possible to substantiate environmentally safe and economically feasible ways of skidding, estimate the ratio of transport development of a forest area using various terrestrial technical means (wheeled and crawler tractors or cable systems), as well as to outline the possible occurrence, intensity and spread of environmental hazards associated with timber harvesting.

Calculation of optimal power and energy saturation of an agricultural tractor

Calculation of the optimum power, operating weight and energy saturation of the agricultural tractor at which the minimum fuel consumption and optimum performance are achieved is an actual task of the tractor theory. The purpose of the study is to determine the optimal power, operating weight and energy saturation of the agricultural tractor at the minimum specific energy consumption - the ratio of energy costs when processing a unit of area to the achieved productivity. Objects of research: combined arable units with wheeled and caterpillar tractors of general purpose. Initial material: nominal traction forces accepted for different traction classes; coefficients that characterize the traction-coupling properties of the tractor; the tractor's power balance equation; skidding function; computer program to minimize the function by the dichotomy method; dependences for dimensionless coefficients that take into account the increase in the specific traction resistance of the unit with an increase in operating speed. The main research method is the calculation using nonlinear programming when the energy saturation is changed by the dichotomy method. When loading with nominal tractive effort, the nominal power of a general-purpose tractor and its maximum energy saturation are determined by the specific energy costs corresponding to the operation of the arable unit with permissible operating speed and slippage. The minimum energy saturation of the tractor is determined by the ratio of the minimum operating power to the maximum operating weight of the tractor corresponding to the maximum traction efficiency. The main conclusions: the specific energy consumption of the tractor on the process operation depends on its type and the dimensionless coefficient, taking into account the increase in the specific traction resistance of the unit with increasing speed and changing in the parabola; the nominal power of the wheeled tractor is in the interval, the lower limit of which determines the minimum specific energy consumption at the maximum traction efficiency, the upper one - the specific energy consumption at the maximum permissible speed and permissible slippage; the rated power of the crawler tractor is determined by the specific energy consumption at the maximum permissible speed and permissible slippage.

Reduction of aftereffect of machine units on the soil

Cultivation of crops is associated with multiple passes of machine units through the fields. The cumulative effect of soil compaction caused by repeated impacts of movers of machine units is considered as especially dangerous. The most intensive compaction process occurres in spring. The repeated passes of heavy machines and the compaction of surface and subsurface soil horizons lead to the decrease in yield potential of fields. The solving of compaction problem depends on the soil and climatic conditions, zonal cultivation technologies and crop harvesting, and on the machine system in operation. When forming the machine and tractor fleet of enterprises, the selection of general-purpose tractors serves as a basis. The least negative impact on the soil occurs when crawler tractors are used. The advantage of wheeled tractors is the possibility of their use for both field works and transport operations. But today the wheeled tractors are hardly used for transport operations because of their increased weight and power, which shows the necessity of use of such heavy crawler tractors as Ruslan and Challenger. Their use in combination with wheeled tractors of middle class allows to improve significantly the structure of machine and tractor fleet. The main power unit for farm enterprises with 1000 hectares of arable land is a general-purpose tractor of the 3rd traction class. The use of the HTZ-150K-09 tractor with 23.1R26 low-pressure tires with the air pressure of 80 kPa provides a permissible impact on the soil. The soil density in the surface layer reduces to 0.06 grams per cubic centimetre as compared to the use of 21.3R24 single wheels. This allows to put such tractor in operation for spring field works.

Noise in cab of a crawler agricultural tractor

The working conditions of operator are considered as one of the most important indicators of technical level of a machine and its competitiveness in agricultural machinery market. The article presents the measuring data of noise level on operator workplace, based on the results of long-term tests of crawler agricultural tractors of 3 drawbar category for general purposes. Measurements of noise level in tractor cabs were carried out according to the requirements of state standards when performing the main type of works, namely the stubble tillage after harvesting of spiked cereals. Tractors produced by Volgograd tractor plant in 1993-2000 conformed to the sanitary regulations of tractors’ and agricultural machines' technology and had the noise level about 78-80 dBA. Subsequent upgrading of crawler tractor’s cab led to worsening of work conditions in respect of noise. Noise level in cab of the Agromash-90TG 1040А tractor produced by Volgograd tractor plant in 2012-2015 reached 88-90 dBA. The analysis of the results of measurement of noise levels allows to make a conclusion that the main noise source in upgraded cab is the exhaust tube of engine. The construction of cab does not protect the operator against the noise of engine. Furthermore, the use of microclimate normalization system in cab of the Agromash-90TG tractor does not provide the reduction in air temperature to a comfortable level of 24-27 degrees C. Test results revealed that working conditions on the new tractor do not conform to the requirements of standards. Specialists of tractor industry organizing a new production of crawler agricultural tractors should take into account the previous experience of engineering developments in Volgograd tractor plant and results of state tests of tractors.

Supervised logging and climber cutting improves stand development: 18 years of post-logging data in a tropical rain forest in Borneo

We analyzed 18yearsof post-logging data from Sabah, Borneo to evaluate the impact of two selective logging methods – Supervised logging (SL) including pre-aligned skid trails and directional felling, and conventional logging (CL), where trees were felled before the crawler tractor was called in for skidding and the fellers had no formal training in felling techniques – on net standing volume recovery, survivor growth, ingrowth and mortality of trees (⩾10cmDBH). The logging treatments were either combined with- (CC) or without (NCC) pre-harvest climber cutting in a randomized 2×2 factorial design consisting 16 one-hectare treatment plots. We investigated the effect on the complete stand including all trees (⩾10cmDBH) regardless of species, but also distinguished between the effects on the commercially interesting species of dipterocarps (Dipterocarpaceae family) and pioneer species (mainly Macaranga species). Supervised logging in combination with climber cutting was in many ways beneficial to stand development and these effects were mainly expressed at higher harvest intensities. For example, supervised logging reduced the ingrowth and survivor growth of pioneer Macaranga spp.; at high harvest intensities approximately 50% fewer pioneers grew in when SL was used in comparision to CL. In addition, climber cutting increased the ingrowth as well as decreased the mortality of highly valuable dipterocarp species with increasing harvest intensity. These effects appeared also to have stand level consequences as forests treated with the combination of supervised logging and climber cutting also exhibited faster recovery in standing volume of high value dipterocarps compared to any other combination of treatments. We conclude that, with improved ingrowth of dipterocarps, reduced overall mortality and generally better stand volume recovery; supervised logging (SL) in combination with climber cutting (CC) could be an attractive forest management system in mixed dipterocarp forests.

Effect of Steering Gear Parameters of Crawler Tractor Cornering Ability

Abstract Crawler tractor with specific loads on the hitch loses traction abilities during cornering and causes intensive destruction of the surface layer of soil. This phenomenon may be limited if relevantly selected parameters of the cornering mechanisms were applied. The objective of the paper was to determine the impact of the cornering mechanism parameters on the crawler tractor maneuver ability. The object of the research was a planetary cornering mechanism which enables fluent change of the cornering radius through the change of the rotational speed of planetary gears drive by pneumatic engines. Relations of the turning radius to the slip of the spinning and overleaping crawler at the speed of 7 km·h-1 without the load on the hitch and with the load of 40 kN were defined. The average values of drift and the turning radius as a function of drive speed from 0 to 2.5 m·s−1 on the moist soil μ=0.4 and dry soil μ=0.8 were determined. Relations of the turning radius to the pressure of oil pump oil, to the drive speed and to the load on the hitch were set forth. The research proved that when using the hydraulic pump with the regulated expense the working pressure of oil may be maximally reduced to 30 MPa, the power of the pump may be reduced by twofold, the possibility of turning in difficult field conditions within the scope of the required speed may be enabled. To ensure the required turning radius of the crawler tractor it is recommended to install the pump with the efficiency of 33 cm3·rot−1 and a regulated hydraulic motor with the capacity of 56 сm3·rot−1 with a power regulation within 2.0-2.5, at the same time maximum pressure of liquid will not exceed 35 MPa and the determined power of the hydraulic gear will amount to 52.6 kW.

Fractional model of viscoelastic oscillator and application to a crawler tractor

Viscoelastic oscillator (VEO) is the basic model extracted from viscoelastic damping structures. To precisely understand the dynamic behavior of VEO, generalized modeling of fractional viscoelastic oscillator (FVEO) is proposed and its frequency response is deduced. For demonstrating purpose, frequency response of three FVEOs is studied. As an engineering application case, the viscoelastic suspension mounted in a heavy crawler-type vehicle is considered and its vibration model is built by FVEO, whose time-domain solution is numerically derived by matrix differential theory. The results indicate that FVEO is a valid approach to evaluate the dynamic response of viscoelastic damping structures.