The paper presents the methodology for designing the teeth conjunction of planetary gears in the planetary roller screw mechanism. A function of the planetary gears is to synchronize an operation of rollers in order to avoid axial displacements. A condition of the correct operation is no axial movement of rollers in relation to the nut. The planetary gears are integral parts of rollers and therefore an operation of the gear transmissions has a direct impact on cooperation of the screw, rollers and the nut. The proper design of gear engagements is essential for reducing slippage on surfaces of the cooperating threaded elements. For this purpose, in a designing method, both the limitations of operation and kinematic conditions of rollers’ operation have to be taken into account.
The new rich collection of fossil fish remains obtained during the Polish Spitsbergen Expedition of 1998 includes many isolated shark teeth, mostly of the genera Lissodus, Hybodus and Acrodus. The shark microfossils from the Hornsund area (South Spitsbergen) described here and the analysis of the histology of Lissodus teeth contribute to a better understanding of the previously described Early Triassic fish fauna from that region (Birkenmajer and Jerzmańska 1979). There is the evidence for coexistence of two types of histology within a single taxon what closes the discussion considering ortho- and osteodentine as a taxonomic factor.
The paper shows the new method for noise reduction in external gear pumps based on the analysis of the pressure in inter teeth volumes. The simulation model and measurement results of pressure changes in the inter teeth volume has been presented. Based on simulation results an additional volume has been obtained, which is connected to the inter teeth volume (decompression filter volume). Due this additional volume the build down processes in the pump are longer and the pressure overdue in the inter teeth volumes are smaller. This leads to the reduction of the dynamical excitation forces inside the pump and noise, especially in the higher frequency rangeI.
The solution of planetary gear with simplifying technology using the same geometry of the sun gear and the central gear is already known. The authors decided to change this concept i.e. to design a planetary gear with the same geometry of satellite wheels, which cooperate with a sun gear and a central gear with different number of teeth. The structural solution of elements of the gear is analyzed taking advantage of computational technique. Geometrical dimensions are described for the sake of teeth correction. Calculations and structural solutions of this kind of transmission are shown in the article.
The aim of this article is to present the design procedure for determining modification coefficients of toothed wheels of involutes planetary gear train with internal conjunction of teeth. It is possible to obtain a higher load-carrying capacity which depends also on correction coefficients. For example, we take into consideration a concept of planetary gears in which the teeth can be corrected, which allows better fatigue and contact surface strength. Two cases are considered when the namely zero center distance (without corrections) of the central and satellite wheels is the same or not, in relation to the zero center distance between the satellite and the sun wheel. Geometrical dimensions are described with regard to the technological teeth correction scope, and inequality restriction conditions are determined with respect to the ISO standards recommendations and the literature. The procedure can be applied to any other planetary gears with another kinematic connection of wheels.
en
pl
