Cognate connections and their application to function cognates and overconstrained linkagesVerwandte gliedergruppen und ihre anwendung bei gleicwertigen übertragungsgetrieben und bei übergeschlossenen getrieben

A simple short cut to finding some of the function cognates of a spatial spatial single-loop linkage is as follows. Replace the floating connection between the input and outputlinks by a cognate connection without disturbing the geometry of the input, output and fixed links. The cognates of the -CR_oC-, -CRC-, -RRS-, -RRE- and -PRS- connections are systematically obtained. These are then shown applied to the derivation of some function cognates of five-bar mechanisms such as RCRCR, RSRRR, etc. and some four-bar mechanisms. They can further be used as redundant connections to improve force transmission. Almost all the overconstrained four-bars with a connectivity sum of 6 are also derived from these cognate connections.     

Tribologie: Reibung, Verschleiss, Schmierung: Documentation of the Research and Development Programme of the Federal Ministry of Research and Technology (BMFT) Volume seven. Surface Processing, Methods of Treatment

This review considers what inferences regarding the mechanism of wear can be derived from recent investigations into the functioning of machine elements operating under conditions representative of engineering practice. Among the subjects discussed are particle analysis, surface texture effects, stress system, thermal effects, chemical aspects of wear, and ehd effects     

Über den einfluss der oxydationseigenschaft von stählen auf ihren verschleiss-mechanismus durch gleitreibung bei raumtemperatur

Wear of various steels by sliding friction was studied at ambient temperature. Microscopic oxidation characteristics of the steels and the humidity were considered. The specimen materials were low carbon steels, alloy tool steels for hot working, and heat resisting steels with good microscopic oxidation properties and high carbon steels with poor microscopic oxidation properties. Wear tests were made with the “ōkoshi” Rapid Wear Testing Machine in which flat specimens are rubbed on a disk-shaped specimen under a load of 2.1 kg. The sliding distance was 66.6 m, and the sliding speeds were about 0.05 m/s to 3.6 m/s. Wear tests on some materials were made on different days in order to study the influence of the atmosphere. The results that were dependent on the sliding speed showed various forms of curves at the maximum of wear; sharp peaks or rounded peaks. The results are discussed in relation to the microscopic oxidation properties of each steel and the humidity.     

Conjugate positions for planar four-bar mechanisms and corresponding special forms of the coupler-curvesKonjugierte stellungen bei ebenen viergelenkgetrieben und die zugenhörigen sonderformen der koppelkurven

Four-bar mechanisms and their variations yield two positions for which the output angle β or the coupler angle γ is identical. These positions are called “conjugate positions” and their significance is discussed. The kinematic inversions of mechanisms in certain conjugate positions leads to new mechanisms with special coupler curves. Coupler points which trace a path with two cusps are easily determined. A similar treatment of the non-turnable double rocker yields coupler curves with three cusps. Requirements for symmetrical coupler curves with two or three cusps can be satisfied.     

Discrete positions method in kinematics and control of spatial linkagesEine methode der diskreten lagen in der kinematik und steuerung der bewegungen raumlicher mechanismen

Using the screw theory in the field of infinitesimal displacements, the first and second order transfer functions of spatial kinematic chains are algebrised. Based on this, a method of finite increments of the relative displacements in the joints is offered. Finally, an algorithm for the control strategy of open kinematic chains of manipulators and robots was evolved using an imaginary closing of the kinematic chain while bearing in mind the conditions for instantaneous mobility (transitory).     

A survey of the state of the art of cam system dynamicsEin bericht über stand und tandenzen der disziplin der dynamik des kurvensystems

The primary aim of this paper is to review the development and the status of the kinematics and dynamics of cam-and-follower systems. Significant information in the field, scattered over various sources, is examined and brought into a coherent framework of the author's own view of the subject. The areas where fruitful work may be done are indicated.     

Weight and rated characteristics of machines: positive displacement pumps,motors and gear setsMasse und nenndaten hydrauliscer volumetrischer pumpen und motoren und untersetzungsgetriebe

Resuming a previous study [1] samples of positive displacement hydraulic machines and gear reduction units are analyzed, in order to find out correlations between their weight and rated characteristics. The particular tendencies of the positive displacement hydraulic machines resulting from the former work are confirmed and specified in this one. As far as the gear reduction units are concerned, correlations between the variables “weight/rated torque” W/T and “rated power” P pointed out; they are well defined for single fields of output rotation speed. Some hypotheses about the interpretation of those correlations are advanced and further developments stated.     

Über die Berechnung der Eigenfrequenzen von schwingungen bei KurvenmechanismenCalculation of the natural frequencies of vibrations in flexible cam mechanisms

In many cases of relatively flexible cam mechanisms, actual follower motion may be appreciably different from that machined into the cam. Actual motion of the follower is a function of three basic factors: characteristics of the driving displacement function from the cam, other external forces acting on the follower system and mechanical properties of the system. As a basis for evaluating the mechanical properties of the follower system, its natural frequencies are an excellent index, serving as a measure of the system's ability to respond to a given cam command [3]. The model with a single degree of freedom shown in Fig. 1 has been used extensively for calculating the natural frequencies.In the present paper, flexible parts of the system have been regarded as a continuum with one dimension, and the model shown in Fig. 2 has been used for determination of the natural frequencies of vibrations in flexible cam mechanisms. The frequency equation has been found from the partial differential equations and the boundary conditions.Comparison shows that there are considerable differences between the natural frequencies calculated from the models shown in Figs. 1 and 2; an example is worked out assuming a harmonic cam form (equation 8). The comparable figures are given in Table 1: α and α2′ derive from the simplified equations (25)–(28) and α₁ and α₂ from the continuously distributed mass system assumed.     

Konjugierte Stellungen bei sphäerischen Viergelenkgetrieben und die zugehoerigen speziellen KoppelkurvenConjugate positions of spherical four-bar mechanisms and corresponding special forms of the coupler curves

Conjugate positions of spherical four-bar mechanisms are corresponding to planar mechanisms those having the same output-angle ‘β’ and consequently two conjugate positions for every possible value of ‘β’. The geometric relations for conjugate positions of spherical four-bar mechanisms are derived in this paper. Furthermore, it is demonstrated how to gain spherical coupler curves having two or three cusps by kinematic inversion of special conjugate positions.