Originally fixed and uniform circular pitches of flex spline (FS) teeth of a ‘Strain Wave Gearing’ or ‘Harmonic Drive’ (HD) experience variations in pitch lengths when teeth move on ‘strain wave generating’ oval-shaped cam. This is due to varying root deformations of teeth. In case of teeth with widely used involute profile, away from the contacts on line of action through pitch point, they definitely experience force closeness to or separation from the circular spline’s (CS) originally conjugate tooth. We have estimated the deformed pitch distances at no load considering that FS teeth remain rigid while the rim deforms. The geometry of the oval-shaped pitch curve which is parallel to the elliptical outer profile of the cam is also defined. Similarly to maintain an elliptical pitch curve of FS, the oval cam is also defined. Both cases of tooth mesh of undeformed FS with CS and tooth mesh of deformed FS with CS, with involute teeth, are considered to find out tooth positions. Geometries of involute teeth profiles in mesh are examined and compared considering oval-shaped (on deformation) base drum of FS, whereas the base circle of the CS remained circular.

Water hydraulics is coming back as an alternative to oil and other not environment friendly working fluids used in a very wide range of fluid drive and control systems. The cost of water resistant materials for components is one of the barriers preventing the wide use of water hydraulics, especially moving parts such as pump pistons, surface of cylinder tubes and rods, poppet and seats, etc. to avoid corrosion. One of the common solutions is to use stainless steel there, where it can cooperate with other nonmetallic material such as plastic or other noncorrosive metallic composite to reduce friction. Thus some of research was directed to elaboration of special coating for covering surfaces in critical regions of water hydraulic components. The paper describes results of pilot research on selected components where such coating were introduced on regular carbon steel parts, same as used for oil hydraulics. First part of the article contents description of coating technology and some characteristics of coating layers. Second quotes selected results of conducted by authors research on coated hydraulic cylinders and poppet valves.

In the modern world continually grows ecological consciousness of societies. We are looking for new and develop the already known methods of energy generation from renewable sources. Designing of simulation models using newest software (i.e. Simulation X) of existing system and on their base building new allow in an easy and fast way to demonstrate their advantages but also find areas that need to be improve. Based on previous experiences and virtual tests [12] finally was managed to create model of Francis turbine control system using water hydraulic elements. This article presents of the system consisting of three connected and interacting subsystems: hydraulic model of the guide apparatus control system, three-dimensional model of guide apparatus and model of water flow through the system of guide apparatus - turbine.

The paper presents modification of drive and control system for specially developed small size multipurpose mobile platform which has been built based on existing vehicle undercarriage. For such redesigned object new concept of hydrostatic drive and control system is proposed. The control system consists of selected hydraulic components and controllers which were chosen from Sauer-Danfoss PLUS+1 package which is the system dedicated for mobile hydraulic control systems application. The hydraulic system has been equipped with extra valves, enabling to obtain of assumed functions.

Water hydraulics is coming back as an alternative to oil and other not environment friendly working fluids used in very wide range of fluid drive and control systems. One of the barrier causing that water hydraulics is cost of water resistant materials for components, especially moving parts such as pump pistons, surface of cylinder tubes and rods, poppet and seats, etc. to avoid corrosion. One of common solution is to use stainless steel there, where it can cooperate with other nonmetallic material such as plastic or other noncorrosive metallic composite to reduce friction. Thus some of research were directed to elaboration of special coating for covering surfaces in critical regions of water hydraulic components. The article describe results of pilot research on selected components where such coating were introduced on regular carbon steel parts, same as used for oil hydraulics. First part of the article contents description of coating technology and some characteristics of coating layers. Second quotes selected results of conducted by authors research on coated hydraulic cylinders and poppet valves.