Name
Kravchenko Vladimir Alekseevich
Scholastic degree
•
Academic rank
professor
Honorary rank
—
Organization, job position
Don state agrarian University
Web site url
—
—
Articles count: 20
The purpose of the study was to substantiate the rigid parameters of tyres in propulsion units for the combine harvesters of high performance. A research method is analytical with the use of a mathematical model of the combine harvester in which damping and rigidity of the drive axle tyres in circumferential and radial directions are taken into account. Values of the rational rigid characteristics of the pneumatic tyre have been generally determined by the ability of the tyre to be deformed so that to reduce the angular, vertical and horizontal skeleton oscillations of a combine harvester to ensure the high-quality technological process of the threshing and harvesting. The specified circumstance gains the special importance at the development and introduction of the new tyre modes for the combine harvesters of high performance. The analysis of the conducted analytical researches has been showed the expediency of using the threads of a cord in the propulsion unit of combine harvesters instead of diagonal or radial tyres of the same standard size with an original position of them. The offered pneumatic tyre of 30.5E-32 used as the leading one, and promotes the reduction of the angular oscillation amplitude and operating speed of a combine and also angular and vertical accelerations up to 1.42 times
The objective of the research was to study the patterns of deformation with the different internal structure in a tire envelope with the standard size of 30.5-32 in propulsion units for modern mobile farm vehicles. The research method is experimental with the use of «a tire tester» and specially developed devices for determining the deformations of the tire envelope concerning the rim in circular and radial directions. Output indicators of a wheel with the pneumatic tire are determined by the ability of the tire to be deformed so that at small hysteresis losses in the rubber-cord envelope the largest area of the contact with a substructure have been created. This circumstance has special significance when developing the tires for mobile farm vehicles with the high power saturation, the patterns of deformation of which are poorly studied now. The analysis of the carried out experimental researches has shown the expediency of application of the experimental tires with the same standard size, offered in the work, on the propulsion units of the mobile farm vehicles instead of diagonal and radial tires. The rolling resistance of the experimental tires 30.5E-32 is lower than the rolling resistance of serially produced tires, and the developed area of contact is higher and that provides the decrease in the condensing impact on the soil
The aim of the work is to establish rational parameters on the basis of analytical and experimental research, in terms of obtaining the maximum performance of the unit based on a class 5 tractor, an automatic gear shift system. We have proposed a device for automatic gear shifting, in which the pressure of the working fluid in the pneumatic-hydraulic accumulator installed in the power transmission of the tractor of the elastic-damping mechanism, equivalent to the engine torque, was used as an input signal. The task of optimizing the tracking device and the actuator of the automatic shift system is the definition based on the theory of automatic regulation of the rational flow cross section of the damper throttle and the time delay of the system response to ensure the input signal with the necessary filtering in frequency and phase. The study presents the results of the tests carried out under laboratory conditions, which showed that the automatic gear shift system provides gear shifting at an external load frequency in the range from 0 to 0.24 s-1, direct assessments of the quality of the automatic gear shift system: oscillation (0), overshoot (0%) and time of the transition process (2...4 s), meet the requirements for their work. The analysis of the results obtained in experimental studies showed that the productivity of the machine-tractor plowing unit with a class 5 tractor-model equipped with the developed system of automatic gear change is higher by 10.6%, and the specific fuel consumption is 8.1% lower compared to the serial version
The aim of the study is to investigate the
regularities of deflection in the diagonal and radial
tires for the grain combine propulsions of high
productivity. The research method is experimental.
The "tire tester" and specially designed devices for
revealing the deflections of the inner and outer tube
relative to the rim in the circumferential and radial
directions have been used. The outcome indices of
the pneumatic-tired wheel are determined with the
tire capability to deflect so, that at low - hysteresis
losses in the rubber-cord casing and its acceptable
tensions, based on a resource, the largest area of
contact with supporting base would be created. This
circumstance acquires the particular significance
developing tires for grain combines of high
performance, the deflection regularities of which
are poorly studied at present. The analysis of
experimental studies showed the feasibility of using
the grain combine propulsions instead of the
diagonal radial tires of the same size. The resistance
to rolling of radial tires 30.5 R-32 is lower than in
diagonal tires 30.5 L-32, and the developed contact
area due to the increase of length is higher, which
reduces sealing effect on the soil
The aim of the article has been the study of deflection
laws in tractor oversize low-pressure tires, intended for
class 5 tractor propulsion. The research method was
experimental. The "tire tester" and specially designed
devices for determining the deflections of the inner and
outer tube relative to the rim in the circumferential,
radial and collateral directions have been used in it. A
number of factors determine outcome indices of the
wheel with pneumatic tyre. Among them the ability of
the tire to deform so that at low - hysteresis losses in the
rubber-cord casing and admissible stresses in it, based on
resource, the largest area of contact with the supporting
base has been created. This circumstance is of particular
importance in the development of tractor tires of low
pressure, deflection characteristics of which are poorly
studied at present. Analysis of experimental studies
showed the necessity of the feasibility of creating the tire
with the cord orientation in its casing so that in the zone
of perception of the vertical and longitudinal forces the
cord threads would work in a mode close to the
extension, but in the area of contact it would work in
bending. These requirements will best meet the tire in
which the cord threads are parallelly located in adjacent
layers and directed at a predetermined angle in the
direction of effect of the axial forces on the wheel in oncoming fibers
The aim of the article is theoretical and experi¬mental confirmation of the possibility to improve the acceleration performance of tractor units by in¬stalling a tow hitch with variable stiffness. Application of speed tractors in agricultural pro¬duction meets a number of difficulties associated with the unsteady processes, especially while accel¬erating of machine and tractor units. The resulting large inertial loads during acceleration lead to loss of engine power, due to which the machine and tractor unit operates with less performance and economy. Our analysis of published studies shows that the acceleration performance of tractor units is greatly influenced by the rigidity of external links in the form of coupling devices installed between the trac¬tor and the agricultural machine. The design of the tow hitch with variable nonlinear stiffness for class 1.4 tractors is offered. The results of theoretical and experimental studies on the effect of the proposed tow hitch with variable nonlinear stiffness on the acceleration capabilities of machine and tractor units based on class 1.4 tractor are shown. Based on the analysis of characteristics obtained by the analytical and experimental ways, it was proved that the use of the hitch with a variable non-linear stiffness on class 1.4 tractor helps to improve the acceleration performance of the machine and tractor unit
The aim of the work is theoretical and experimental
confirmation of the possibility of improving the rate
of acceleration of tractor units due to installing of
elastic-damping mechanism with variable stiffness in
tractor transmission. Speed tractors application in
agricultural production meets a number of difficulties
associated with the unsteady processes during
acceleration of machine and tractor units. The resulting
large inertial loads when accelerating result in
loss of engine power, due to which the machinetractor
unit is operating at reduced performance and
efficiency. An analysis of published studies shows
that the acceleration performance of tractor units is
greatly influenced by the stiffness and damping
properties of the transmission of energy resources.
To provide smooth acceleration of the unit it is proposed
to install elastic-damping mechanism with
variable stiffness in tractor transmission. As a result,
the tension of the acceleration process decreases. The
results of analytical and experimental studies on the
effect of elastic-damping mechanism installed in the
class 5 tractor transmission, on acceleration capabilities
of tractor units are given. The optimum parameters
of elements of elastic-damping mechanism with
variable stiffness for class 5 tractors are determined.
It is proved that the use of elastic-damping mechanism
with a variable stiffness in the tractor transmission
improves acceleration indicators
The aim of the work is theoretical and experimental
confirmation of the possibility of improvement in
tractor unit acceleration due to the variable inertia
moment of the rotating masses of the engine. The use
of high-speed tractors in agricultural production
meets a number of difficulties associated with unsteady
processes during acceleration of the tractor
units. The emerging significant inertial loads during
acceleration result in the loss of engine power because
of what the machine and tractor unit is operating
at reduced productivity and efficiency. An analysis
of published works shows that the tractor unit
acceleration is strongly influenced by the rotating
mass of the engine. A device based on the application
of additional rotating masses in a free flywheel
connected or disconnected automatically to the main
engine flywheel at appropriate stages is offered. As a
result, the tension during acceleration is reduced.
The results of experimental studies on the effect of
the additional rotating masses on the engine acceleration
characteristics of the machine and tractor units
on the basis of Class 1.4 tractor are given. It is
proved that the use of the tractor additional rotating
mass connected or disconnected to the respective
modes of movement of a machine and tractor unit to
the flywheel of the engine, improves acceleration
performance
The developed mathematical model of the machine and tractor unit with the elastically damping mechanism in transmission of a tractor is given in the article. The analysis of mathematical model of the arable unit on the basis of a tractor with EDM in transmission showed that the MTU mathematical model can be considered as working
The article is devoted to mathematical modeling of random process that occurred in tensile load of serial and experienced MTU. The efficiency of EDM application in transmission is discussed