This project has been assigned by SwePart Transmissions AB. It is about calculation and dimensioning, of the elements in a cycloid stage of a speed reducer. Their idea is to use the results from this project and go into production of such reducer to cover another segment of the market. The company is interested in supplying transmissions for robust systems and for various industrial purposes, where large ratios of speed reduction are needed. The company has given the necessary input data for the model. They have also provided a real cyclo-drive reducer for further analyses. To obtain the dimensions and forming the geometry of the gears, some parts of Professor Ognyan Alipiev’s Phd work have been used. Professor Alipiev is head of “Theory of Mechanisms and Machines” department in University of Ruse “Angel Kunchev”, Bulgaria. For the determination of forces on the elements, models and drawings has been used Solidworks (SW) CAD software and SW simulation environment. The resultant calculation process can be used for designing the geometry and determination of the properties regarding the cycloid reducer. / Design of a Planetary-Cyclo-Drive Speed Reducer

Gibbsite scale growth in pipe fittings is a major problem for an alumina refinery. A recent investigation into the scale growth mechanism at an alumina refinery found almost 60 % more scale growth in a reducer when compared with the connecting straight pipe sections for similar flow conditions. Scale growth occurs where liquor (supersaturated solutions) come in contact with solid surfaces and it is affected by the liquor flow velocity besides other physical and chemical parameters. The present work is dedicated to study the hydro-dynamical aspects of the mechanism of scale growth. In particular, the role of the phenomenon of turbulent bursting, stream wise and cross stream fluctuating velocity components (Ux and Uy) was investigated as the flow moves through the reducer. Particle Image Velocimetry (PIV) technique was used to get a full view of the reducer and the readings close-to-the-wall of the reducer at Reynolds number of 27,000 and 44,000 upstream which corresponds to Reynolds number of 41,500 and 66,000 downstream of the reducer respectively. The results showed an increase in cross stream and a decrease in magnitude of stream wise fluctuating velocity components, whereby we presume that the increased cross stream fluctuating velocity component increases the frequency of impacts of the scaling particles on the wall thus initiating excessive scale growth in the reducer when compared with the connecting straight pipe sections, for similar flow conditions.

Double-Enveloping Reducers are used widely in various industries. In this study, a procedure is developed to analyze the geometric and kinematic properties of such a rotational reducer. In the mechanism, the globoidal worm profile is derived by using the sweeping method and the profile of the globoidal worm wheel is obtained by employing the screw theory. Based on Standards of the American Gear Manufacturers Association (AGMA 6030-C87), the involved parameters in designing and analyzing the reducer are revealed. Finally, the transmission errors based on tooth the contact analysis (TCA) are also reported.

Rotary tables are generally regarded as the forth axis of machining tools. Traditionally, gear sets are used as reducers in the rotary tables. In order to improve the positioning accuracy, load and efficiency of rotary tables, a rotary table which applies the roller gear cam reducer is proposed. From the deduction of the theory, applications of roller gear cam reducers in the industries can be achieved. This thesis is focused on developing the procedure as follows: Firstly, the type of roller gear cam reducer and design parameters are identified. Secondly, the mechanical characteristics of the device are analyzed. Finally, a rotary table is designed and implemented to investigate the performance of the of the roller gear cam rotary table.

This dissertation contains the results of two different projects. The first one is a study of the transport of protozoa pathogens Cryptosporidium parvum and Encephalitozoon intestinalis in soils. The aim of this project was to investigate the movement and retention mechanisms of these microorganisms in natural porous media. The work determined that in the case of C. parvum, the retention was primarily produced by straining and in the case of E. intestinalis the main retention mechanism was attachment. The results of C. parvum lysimeter experiment compared to the results from the 7 cm column experiments suggest that retention is proportional to the length of the column. The second study evaluated the Polymerase Chain Reaction (PCR) as a tool to identify dechlorinating bacteria in groundwater contaminated with chloroethenes. The target DNA regions to identify these microorganism were the 16s rDNA specific for dehalococcoides sp. and Desulfuromonas and DNA sequences coding for the reductive dehalogenase enzymes pceA, tceA, bvcA and vcrA. Bacteria able to transform PCE into DCE were detected in all groundwater samples. Bacteria able to transform VC into ethene were found only in one of the samples. This study shows that PCR analysis of 16s rDNA and reductive dehalogenase gene sequences together with microcosm results are useful tools to analyze the populations of reductive dechlorinators and their activity in a given site.

Šiame darbe modeliuojamas žirklinis keltuvas skirtas kroviniams ir žmonėms kelti, nagrinėjama konstrukcija, detalių stipruminiai skaičiavimai atlikti panaudojant medžiagų atsparumo formules, bei programinę įranga skirtą inžineriniams skaičiavimams bei projektavimui(solidWorks). Žirklinio keltuvo techninės charakteristikos: maksimali keliamoji galia mmax¬= 600kg, kėlimo aukštis Hmax¬=4m 1.Patikima ir paprasta konstrukcija, Maži gamybos kaštai,pigi eksploatacija, patogus naudojimas. Darbo uždaviniai: 1.Sumodeliuoti žirklinį keltuvą kuris atitiktu jam keliamus reikalavimus. 2. Pritaikyti sraigto-veržlės pavarą keltuvui. 3. Atlikti detalių analizę su COSMOS Express programa. Darbe modeliavimui ir detalių tyrimui panaudotas automatizuoto projektavimo paketas SolidWorks. Automatizuotu projektavimo paketų panaudojimas, žymiai sumažina gaminių projektavimo laiką, patikimai ir greitai atliekama detalių ar mazgų analizė, sumažėja projektavimo kaštai. Keltuvo žirklių analizei panaudota programa COSMOS Express atlieka skaičiavimus baigtinių elementų metodu, skaičiavimai yra gan greiti ir patikimi. Darbe sumodeliuotas keltuvas atitinka reikalingas technines charakteristikas, nesudėtinga konstrukcija, lengvai eksploatuojamas, patogiai transportuojamas. / Lift tables are used to raise and position work pieces for ergonomic access. They are typically used for material positioning, load positioning, or lifting. Lift tables are work platforms used to raise and lower material and work pieces for loading and work positioning. They are widely used in construction, automotive and garage service, electrical and power service, telecommunications, manufacturing, inventory management, wire and cable industries, painting and other applications where access to above ground locations is crucial. Important specifications when considering lift tables are lift capacity, vertical lift travel, platform width and platform length. The lift capacity is the maximum force or load supported by the lift. Vertical lift travel describes the difference between fully lowered and fully raised lift positions. The platform width is the narrow dimension of the lift platform. Platform length is the long dimension of the lift platform.

Shaft mounted speed reducers are used in material handling applications, such as conveyor systems for transporting ore out of mine shafts. A subbase joins the reducer with an electric motor, and serves to limit the misalignment between the motor shaft and the reducer input shaft. The entire assembly is supported at two points: the axis of rotation of the reducer output shaft, which is fixed, and a clevis-pin joint under the motor, which prevents rotation of the assembly about the reducer output shaft axis. In an effort to reduce the production and material costs of subbases that support shaft mounted reducers, Rexnord Corp. is implementing subbase designs that are lighter weight and easier to manufacture than current designs. Impeding the implementation of lower cost designs is the lack of an equation to properly choose subbase dimensions for acceptable values of shaft misalignment. Trial and error in subbase construction may provide designs that give acceptable results for misalignment. Given an equation, however, the weight could be minimized while still limiting misalignment at the coupling location. The project goal is to provide equations that give shaft misalignment as a function of three subbase parameters: tube thickness, mounting strap width, and end cap thickness. Developing design equations by analytical methods is investigated first. Next, finite element models are used to check the analytical results for accuracy. Finally, finite element models are used to perform design sensitivity studies where needed. The final equations for misalignment are given as functions of the three design variables. / Master of Science

Despite the sustainable development goals to increase access to improved water there are still 884 million people in the world without access to an improved water source (WHO, 2017). One method to improve access to water in rural, mountainous areas, is through construction of gravity fed water distribution systems. These systems should be designed based upon fundamental principles of hydraulics. One method of doing so in a time efficient manner with minimal engineering knowledge is to utilize a downloadable computer program such as Neatwork, which aids in design of rural, gravity fed water distribution systems and has been used by volunteers in Peace Corps Panama for years. It was the goal of this research to validate the results of the Neatwork program by comparing the flow results produced in the simulation program with flow results measured at tap stands of a rural gravity fed water distribution system in the community of Alto Nube, Comarca Ngöbe Bugle, Panama. The author measured flow under default Neatwork conditions of 40% faucets open in the system (in the field an equivalent of 8 taps) to have an initial basis as to whether the Neatwork program and field conditions yielded corresponding flows. The second objective would be to vary the number of taps open if the default condition did not produce comparable results between the field and the simulation, to pinpoint if under a certain condition of open faucets in the system the two methods would agree. The author did this by measuring flow at varying combinations from 10-100% of the open taps in the system (2-20 taps). Lastly the author observed the flow differences in the Neatwork program against the field flows, when the elevation of water in the water reservoir is set to the Neatwork default, where elevation of water is the tank outlet (at the bottom of the tank) versus when the elevation is established at the overflow at the tank (at the top of the tank) for the case of two taps open. The author used paired t-tests to test for statistical difference between Neatwork and field produced flows. She found that for the default condition of 40% taps open and all other combinations executed between 30-80% taps open, the field and Neatwork flows did not produce statistically similar results and, in fact, had the tendency to overestimate flows. The author also found that the change in water elevation in the storage tank from outlet to overflow increased the flow at the two taps measured by 0.140 l/s and 0.145 l/s and in this case, did not change whether the flows at these taps were within desired range (0.1 -0.3 l/s). Changing the elevation of the water level in the tank in the Neatwork program to correspond to a “full” tank condition is not recommended, as assuming an empty tank will account for seasonal changes or other imperfections in topographical surveying that could reduce available head at each tap. The author also found that the orifice coefficients, θ, of 0.62 and 0.68, did not demonstrate more or less accurate results that coincided with field measurements, but rather showed the tendency of particular faucets to prefer one coefficient over the other, regardless of combination of other taps open in the system. This study demonstrates a consistent overestimation in flow using the computer program Neatwork. Further analysis on comparisons made show that between field and flow results across each individual faucet, variations between Neatwork and the field were a result of variables dependent upon the tap, such as flow reducers or errors in surveying. Flow reducers are installed before taps to distribute flow equally amongst homes over varying distances and elevations and are fabricated using different diameter orifices depending on the location of the tap. While Neatwork allows the user to simulate the effect of these flow reducers on tap flow, it may not account for the imperfect orifices made by the simple methods used in the field to make such flow reducers. The author recommends further investigation to be done on the results of field flow versus Neatwork simulated flow using other methods of flow reducer fabrication which produce varying degrees of accuracy in orifice sizing. The author also recommends executing these field measurements over a greater sample size of faucets and more randomized combination of open/closed taps to verify the results of this research. More work should be done to come up with a practical solution for poor and rural communities to fabricate and/or obtain more precisely sized flow reducers. A full sensitivity analysis of the input variables into the Neatwork program should be performed to understand the sensitivity of varying each input.

The RV reducer (one tpye of cycloid reducer) which has two stage transmissions is widely used in manyfields of engineering. This project is going to design the first stage of the RV reducer, as well as therelated components. The details contain design of input shaft, planetary gears, output shaft, generalbearings and eccentric bearings. The fatigue analysis is mostly used in the calculation process becausethe fatigue failure happens frequently in such rotation machine. In the same time, the general bearingsdesign is based on SKF General Catalogue and the eccentric bearings design is supported by theChinese standard.

This thesis is about design of reducer for six-cylinder aircraft engine. There are processed every parts of reducer and the assembly with crankshaft, torsional vibration of complete assembly and calculation of service life of every individual part.