Mechanisms of power distribution: principles of kinematic and force analysis

The article considers the features of performing kinematic and power analysis of a controlled power mechanism for the transmission of wheeled transport and transport-technological machines. Such mechanisms are currently used mainly on cars in order to improve handling, stability, traction and dynamic properties in severe road conditions. Such mechanisms are not produced in Russia, but theoretical studies are currently being conducted, the results of which will allow determining the main parameters of the mechanism and synthesizing its kinematic scheme. The proposed approaches are based on the methods used in the kinematic and force analysis of planetary gears, but it is taken into account that the mechanism of power distribution during operation has two degrees of freedom. It is indicated that there is a structural and functional similarity between the power distribution mechanism of the car and the turning mechanism of the tracked vehicle. A method is proposed for calculating the gear ratio of the power distribution mechanism according to the condition of matching the minimum possible turning radius provided by the steering trapezoid kinematics and the calculated turning radius.

The Impact of Vibration Operational Reliability of Turning Mechanism of Gantry and Tower Cranes

Impacts of vibration on operational reliability of turning mechanisms of gantry and rower cranes are considered. Besides that, the structural features of kinematic chain of drive, including gear transmission with internal large module teeth, roller bearing without retaining ring, excitement of torsional, bending low-frequency vibrations at operation in nominal mode of cargo lifting that causes the origination of of increasing friction moment and stop of turning mechanism are researched in this article. Moreover, the technological and structural solutions aimed on decreasing of excited vibrations are proposed, and the supporting-rotating rolling bearings without retaining ring with improved technical-economic indicators are considered.

Optimization of rotate mode at constant change of departure in the level-luffing crane with geared sector

The results of optimization of the rotation mode of the level-luffing boom system of the crane at the launch site, with the steady-state mode of departure change. The object of the study is a boom system with a sector drive of the mechanism of change of departure. The mechanism of rotation consists of an electric motor, a planetary mechanism and an open gear. Variation calculus methods were used to optimize the mode of rotation of the boom system. In this case, a variational problem is formed, which includes the equation of motion of the boom system when turning and changing the departure, the optimization criterion and boundary conditions of motion. The optimization criterion has the form of an integral functional that reflects the root mean square value of the driving torque of the drive mechanism of rotation during start-up. The study was carried out at the starting point of the electric motor of the turning mechanism from the state of rest to reach the nominal speed and at a steady speed of rotation of the electric motor of the mechanism of change of departure. The solution of the problem is presented in the form of a polynomial with two terms, the first of which provides boundary conditions of motion, and the second minimizes the criterion of optimization through unknown coefficients. To do this, use a software package. Graphs of change of kinematic characteristics of cargo and boom system at work of mechanisms of turn and change of departure, and also the driving moment in the course of start of the mechanism of turn which correspond to an optimum mode of movement are constructed. The resulting mode of movement allowed to eliminate the oscillations of the load on the suspension. Based on research, recommendations for the use of the obtained optimal start-up mode have been developed.

Anomalous propulsion regime in axonemal-propelled cargoes

Bio-actuated micro-swimmers provide a platform to understand physical principles related to the motion of micro-organisms at low Reynolds numbers. Here, we used isolated and demembranated flagella from green algae Chlamydomonas reinhardtii as an ATP-fueled bio-actuator for propulsion of micron-sized beads. Chlamydomonas flagella have an asymmetric waveform, which can be accurately described as a superposition of a static component corresponding to an arc-shaped intrinsic curvature, a mode describing the global oscillations of the axonemal curvature, and a main base- to-tip traveling wave component. By decomposing experimental beat patterns in Fourier modes, and applying resistive force theory, we performed numerical simulations and obtained analytical approximations for the mean rotational and translational velocities of a flagellum-propelled bead. Our analysis reveals the existence of a counter- intuitive anomalous propulsion regime where the speed of the flagellum-driven cargo increases with increasing the cargo size. Further, it demonstrates that in addition to the intrinsic curvature and even harmonics, asymmetric bead-flagellum attachment also contributes in the rotational velocity of the micro-swimmer. This turning mechanism induced by sideways cargo attachment has potential applications in fabrication of bio- actuated medical micro-robots in the subject of targeted drug delivery and synthetic micro-swimmers.

METHOD FOR DETERMINING HEATING OF DUAL-DISC STOP BRAKE PARTS OF A LIGHT TRACKED MACHINE WHEN OPERATING ON A DIESEL INERTIA STAND

A method has been developed for determining the heating of parts of a double-disc stopping brake for the gear and turning mechanism of a light transport tracked vehicle with a high specific power (over 30 hp /t) when operating on a diesel inertial stand.

Increasing Mobility of Tracked Vehicles during Curvilinear Motion by Redistributing Power Flows

A kinematic diagram of an electromechanical transmission of a high-speed tracked vehicle with two traction electric motors, on-board gearboxes and a ZK-type differential turning mechanism, which makes it possible to effectively distribute power flows between the sides during curvilinear motion, is proposed.

Oscillation of gear mechanisms of construction machines

The article is devoted to the study of the influence of gearing errors on the vibration activity of the open gear transmission of construction machines. A brief review of the literature on the relevance of the topic of gear dynamics in different industries and the results achieved so far is given. The features of open gears of turning mechanisms of construction machines are highlighted: a large gear ratio, a large gearing module, the absence of a common frame for the gear and wheel, poor transmission lubrication conditions, a small degree of precision in the manufacture of gears and the actual overlap coefficient is close to one. With these features, the main internal source of vibration is the difference between the main steps of the gear and the wheel and the error of the involute profile of the teeth. The results of the study of the influence of these features of vibration damping and open gear transmission on the dynamics of the turning mechanism of the construction machine are presented. The studies were carried out on a generalized two-mass nonlinear dynamic model with internal perturbation from the gear pair and with structural damping. The studies were conducted mainly for the transitional modes of resonance. Based on the analysis of the results obtained and presented in the article, recommendations are given to reduce the fluctuations of the turning mechanisms of construction machines.

THEORETICAL SUBSTANTIATION OF CATERPILLAR TURN IN PLACE WITH DIFFERENTIAL STEERING GEAR AT NEUTRAL IN TRANSMISSION

The paper is dedicated to the operation investigation of the two-flow hydro-mechanical transmission of industrial tractor consisting of a hydro-transformer and a planetary gearbox in a basic flow of power ensuring rectilinear motion, and a hydro-volume gear in the second flow ensuring rotation speed difference of caterpillar tracks, and, accordingly a tractor turn. A turn in place of a track machine is ensured with the differential variable-ratio gear of turning on the basis of a hydro-volume gear. The investigation method – simulation. In the course of investigations there was created a simulator describing adequately a turn in place of a caterpillar with a differential turning gear based on a hydro-volume gear. The solution is carried out in the ALTAIR EMBED programming environment. There are made diagrams of the process of going into a turn in place and a steady-state turn in place. At that there was accepted an assumption that the resistance to rotation of the right and left driving wheels of a tractor is equal as it is impossible to suppose that under caterpillars there can be soil with properties different considerably as the rotation takes place in the same place. The analysis has shown that the left and right sides balance each other at the turn on homogeneous soil. The application of a braking device in a general link of the differential variable-ratio in the turning mechanism is optional. The results can be used for example for the further scientific work in the field of quantitative assessment of skidding during tractor rotation round a gravity center having a substantial influence upon controlled kinematic parameters of a tracked vehicle – an angular velocity of turning in place.