Some Aspects of the Structure of Planar Mechanisms

Abstract

The machine is a technical system made up of distinct kinematic component parts (called kinematic elements) which, following the imprinting of movements imposed on an element or elements (considered as leading elements), cause movements to all other kinematic elements in order to execute a useful mechanical thing, or transforming some form of energy into mechanical energy. It follows from the previous definition, three essential characteristics of the machine: the machine is a technical system; its kinematic elements have determined (desmodromic) movements; either to perform either a useful mechanical thing, calling it a lucrative machine, or transforming some form of energy into mechanical energy, bearing the name of a motor car. The lucrative machines are cars, locomotives, motor wagons, presses, machine tools, pumps, compressors, agricultural machines, lifting and transporting machines, etc. The motor vehicles are external combustion (Stirling, Watt) or internal combustion engines (Lenoir, Otto, Diesel, Wankel, star), turbines, hydraulic motors, reaction engines, pneumatic motors, electromagnetic), ionic engines, energy beam or LASER motors, etc. The most used mechanisms in machine building were and still maintain those that operate in a plane or in parallel planes. For this reason, new analytical methods have been developed and developed to determine all the essential aspects of these mechanisms in order to improve the design of machine components. For this reason, it is necessary to present a general presentation of the mechanism of the design of the mechanisms, the present paper dealing only with the first aspect, namely the structure of the planar mechanisms. The most common mechanisms are planar, with bars, toothed, with cams, with a mortar cross, with chains, with belts, with tracks, with bolts, with liquids (hydraulic or sonic), with air (pneumatic). However, spacecraft with universal cardan shaft (universal joint) and cardanic transmission, with hyperboloidal gears (with cross axles), with pivots (spherical couplings), especially steering and suspension mechanisms, tripod mechanisms, mechanisms with space cams, screw and nut mechanisms, robots, serial and parallel systems, steppers, etc. The mechanism, as we have already shown, is composed of kinematic elements connected by kinematic joints (or couplings).