This paper discusses an innovative approach to experimentally determine the behaviour of rotational pivot behaviour by photogrammetric measurements. The compliant rotational pivot was selected for research as it is a well understood compliant mechanism whose deformations can be calculated analytically or numerically, allowing easy verification of the results. The mechanism was redesigned for monolithic additive manufacturing with the selection of printing directions that have reduced the influence of material anisotropy. Rapid developments in image processing and computer vision have resulted in integration of photogrammetry and digital image correlation into a wide range of applications. The primary contribution of this article is in the custom designed experimental pure bending load testing setup with an additional optical displacement measurement system, which was used to study the behaviour of additively manufactured compliant mechanisms. A high quality, consumer-grade camera was used for image capture, while image processing was performed using ready-made and custom developed MATLAB tools. Also, a redesigned compliant mechanism with sufficient precision for applications in low-cost, single-use compliant precise positioning systems was developed, and it was determined whether the selected experimental method is applicable to the research of monolithic compliant rotational joints. The experimental results obtained using this method have been compared to results obtained using finite element analysis and analytical calculations, and it was shown that the results are in good concordance. Therefore, it was concluded that photogrammetric analysis aided by feature recognition is applicable to the measurement of parasitic shift of compliant mechanisms.

The gearbox has been designed as a two-carrier unit with two brakes, and it has been depicted using the Wolf-Arnaudov symbols. The ideal torque ratios for six pairs of reversing gear ratios have been determined and the relationship between the ideal torque ratios of both planetary gear setsrequired for obtaining reversible transmission ratios was determined. The efficiencies were determined for all considered cases. It was determined that the gearbox has relatively high parasitic power in all cases of operation with the brake Br2 active, and the parasitic power function and its intensity were determined. The procedure was performedassuming two constant component gear train efficiencies, namely η0 = 0.98 and 0.95.

Planetary gear transmissions are essential components of industrial machinery due to their small size in relation to their rated power, high transmission ratios, and capability to transmit large torques within a compact design. They are widely applied in automotive, aerospace, and construction machinery industries owing to their reliable and efficient power transmission. The efficiency of planetary gearboxes directly influences energy consumption, operating costs, and environmental footprint. Power losses arise from gear and bearing friction as well as oil churning, and are determined by design parameters, manufacturing quality, lubrication properties, operating speed, and oil temperature. The accurate quantification of these losses is crucial for gearbox design, performance optimization, and durability, as well as for the development of energy-efficient control systems

This paper deals with the selection of optimal layout variants of planetary transmissions designed for operation as Light Electric Vehicle main gearboxes. The required transmission ratio was calculated, and the optimal two-carrier gear train with two connecting and three external shafts selected. A computer program was used for structural synthesis and to determine the required basic parameters of the component gear trains. The ring gear reference diameter was used to rank the layout variants according to size, with the smallest variants also ranked according to the calculated efficiency ratio. Finally, an optimal variant of the planetary gear train for light electric vehicle application is proposed. The procedure proposed in this paper may be expanded to other applications.

This article deals with the research and analysis of electric motors and their matched transmission systems within the context of a versatile electric mini-tractor designed for tasks such as street cleaning, urban park maintenance, and transportation of small loads. The primary objective of the research is to assess the strengths and weaknesses of several electric motor and transmission combinations designed to meet the specific operational demands of the tractor. As the driveline has to provide substantial torque while maintaining optimal operating conditions and avoiding overheating, a series of experiments were conducted, covering various electric motor configurations operating within the 60V range, with power outputs ranging from 1000 to 1500 watts and including multiple gearbox variations. A comparative analysis was performed to assess the advantages and disadvantages of direct chain drive transmission solutions without a differential on a rigid axle, in contrast to a sealed motor-gearbox unit featuring differential and semi-axles. The results of this research were used for mathematical comparison of the driveline solutions, enabling the detection of optimally matched transmission and motor solutions. The experiments also covered the identification of energy-efficient solutions and optimal design parameters for an electric tractor explicitly designed for continuous operation exceeding 10 hours, with cargo capacity exceeding 500 kg, high off-road maneuverability, and a service life exceeding 5000 hours. The dynamic tests carried out during the research have provided valuable insight into the relation of the overall power efficiency of the vehicle to the weight and transmission ratio variations.

The ever-increasing demands for vehicle emission control have resulted in an expansion of planetary gearbox applications in road vehicles, due to their possibility to change the transmission ratio under load in synchronism with engine operation. Modern boxes are designed to extract the maximum number of transmission ratios as possible from the least possible number of simple component planetary gear trains (PGTs). The application demands dictate whether the box will be built with the maximum number of transmission ratios, or built for ruggedness and reliability. Component interconnections are designed to avoid power circulation, hollow shafts, or complex planet carrier arrangements when possible. The subject of this paper are multi-speed complex planetary gearboxes having at least two interconnected simple component PGTs controlled by brakes and clutches. Several variants of complex PGTs are examined together with the placement of brakes and clutches on their external shafts, and their transmission ratio functions are derived. The kinematics of multi speed gear trains are analysed as combinations of two or more two-speed gear trains. Several gearbox layouts are analysed, and their transmission ratio functions provided. Finally, an overview of the procedure for the calculation of creation of multi-speed gear trains is provided.

Humanity is shifting its power generation to renewable energy, notably wind power. As more and more wind power plants are built, it has become important to improve the efficiency of wind power generation and reduce the manufacturing costs of wind power equipment. The mechanical multiplier gearbox is one of the most important parts of the wind power turbine, and it is now being built as a planetary gear train as these gearboxes offer a compact build capable of high power ratings in a relatively small package with coaxial input and output shafts. It is very important to select the right kinematic scheme and the other relevant parameters in the early design stages as the wrong kinematic scheme will result in a suboptimal solution. This article deals with the selection of the optimal gearbox solution for a 700 kW wind turbine application, taking into account both two-carrier and three-carrier gearbox solutions. As the optimal solution may be deducted only by systematic analysis, the proprietary 2-SPEED software has been developed for this purpose. The results of the analysis have been presented in this article, and optimal gear train solutions have been suggested for both two-carrier and three-carrier multiplier configurations.

The increased demands for driver comfort and stringent pollution control measures have resulted in a revival of planetary gearboxes for road applications, due to their possibility to change the transmission ratio under load in synchronism with engine operation. Modern boxes provide as many transmission ratios as possible from the least possible number of simple component planetary gear trains (PGTs) by providing links between elements of multiple component PGTs. The application conditions decide to prioritize either the maximum number of transmission ratios, or ruggedness and reliability. Power circulation, hollow shafts, or complex planet carrier arrangements are avoided if possible. This paper deals with multispeed complex PGTs composed of at least two interconnected simple component PGTs controlled by brakes and clutches. Several variants of complex PGTs and the placement of brakes and clutches on external shafts of the gear trains are examined, and the transmission ratio functions derived. The kinematics of multi speed gear trains are obtained as combinations of two or more two-speed gear trains. An analysis of several contemporary gearbox layouts is provided together with the transmission ratio functions, together with an overview of the procedure for the calculation of creation of multi-speed gear trains is given.

The mechanical multiplier gearbox is one of the most important parts for wind power generation efficiency. Modern epicyclic gearboxes are compact, lightweight builds capable of high power ratings with coaxial input and output shafts. To achieve this, it is very important to select the proper internal gearbox layout and other relevant parameters in the early design stages as the wrong choices will result in a suboptimal solution. Parametric optimization was applied to select the optimal gearbox solution for a wind turbine application, while taking into account both two-carrier and three-carrier solutions. The large number of possible solutions has resulted in the development of the 2-SPEED software to conduct systematic analysis and comparison. The best five two-carrier solutions and the one best three-carrier solution have been selected from the solution pool, with the selection being based on the criteria of maximum efficiency, minimum weight, and minimal greater-ring diameter size. One optimal two-carrier solution was then selected from the five and compared to the three-carrier solution. Recommendations for the selection of either two-carrier and three-carrier gear train solutions according to the application demands have been deducted and provided. This will result in lighter, more efficient designs with smaller radial dimensions.

The subject of this paper is a two-carrier planetary gear train (PGT) which was developed for a specific purpose. This PGT may be used for applications in which a negative transmission ratio in the range -3…-143 is required. In this case, the mechanical and dimensional properties of the PGT have been analyzed for nominal negative transmission ratios of -30 and -40. All possible combinations of simple component PGT ideal torque ratios providing those transmission ratios were obtained. Only the combinations providing the minimum radial dimensions of the PGT assembly were selected. Subsequent analysis has shown that the PGT radial dimensions will be minimized when the ratio of the reference diameters of the planetary unit ring gears is close to unity, meaning that the PGT casing will be cylindrical rather than stepped. This paper also provides an overview of the DVOBRZ software package used to synthesize the different gearbox layouts for the required transmission ratio, combined with a basic introduction to single speed two-carrier PGTs for better understanding. The DVOBRZ software was used to select all the acceptable gearboxes were selected from the set of generated PGTs according to the criteria of minimum dimensions and acceptable efficiency range. This set of PGTs was checked for kinematic feasibility and construction concepts were created for feasible layouts.

Internal combustion powered railway vehicles require extremely rugged and reliable transmissions. While high-powered applications use electric or complex hydrodynamic transmissions, in the low to medium power range of railway vehicles, transmissions derived from ordinary highway truck or bus automatic transmissions and hydromechanical transmissions, are used. Modern railway vehicles must be able to operate in both directions at the same speed, which is particularly important when units from the same series are connected in a multiple unit lash-up. Simple hydrodynamic and mechanical transmissions are commonly used in such vehicles, but planetary gear trains are also suitable for the application, either as an output gearbox or as the main transmission gearbox in the case of simpler vehicles. This planetary gearbox is designed to provide two equal transmission ratios, however with the output shaft rotating in different directions. Design priority should be given to clutch-type brakes for compactness and reliability, however band brakes should have priority for ease of maintenance is a priority. Additionally, the gearbox design should give priority to boxes that do not experience power circulation, and do not require hollow shafts or complex planet carrier arrangements. The application of planetary gearbox designed according to the guidelines laid out in this paper would simplify the design and manufacture of hydrodynamic, hydromechanical and mechanical transmissions for railway vehicles.

There are many challenges in compliant mechanism redesign for additive manufacturing (AM) technologies, and in order to assess their applicability and propose adequate recommendations, the behavior of compliant elements has to be examined. Plastic materials are often used in AM technologies and are well suited for large volume compliant mechanisms due to their flexibility to strength ratio. However, they also have many disadvantages, notably a low fatigue strength and complex material behavior. Therefore, in this paper a photoelastic observations of corner-filleted flexure hinges manufactured from the transparent acrylic based photopolymer using the Digital Light Processing (DLP) AM technology subjected to the dynamic loading have been conducted in order to assess the fatigue strength and potentials of the photoelastic methods for the material behavior modeling. Three-point flexural tests on rectangular beam samples with the standardized dimensions printed in vertical and in horizontal orientation have been performed and the obtained data has been used for numerical simulations of corner-filleted flexure hinges. The specimens printed in different orientations exhibit significantly different anisotropic properties; the horizontally printed samples exhibit brittle behavior, while the samples printed vertically yields and consequently have much higher deformations, the calculated flexural moduli are also very different. Corner-filleted flexure hinges printed in vertical orientation and subjected to dynamic cantilever beam bending tests at relatively high stress amplitudes proved sufficient for the low dynamic compliant mechanisms applications. The qualitative photoelastic observations have shown that the photoelasticity is applicable in dynamic tests and useful in residual stress determination and stress concentration investigations.

An alternative method for kinematic and power analysis of compound gear train is presented, which uses the torques and lever analogy of a given gear train. The method combines the accuracy of the Willis analytical method with the clarity of the graphic method of Kutzbach. Unlike these methods, the torque method allows determining not only the gear ratio, but the magnitude and direction of power flows, and hence the determination of efficiency of a given compound planetary gear train. The application of the method is illustrated with example of novel arrangement of complex nine-speed change-gear. Structural, kinematic, and power (efficiency) analysis are made. A software for these analysis facilitation is developed. A numerical example is presented and discussed.

A two-carrier planetary gear train (PGT) configuration, named S13WN, was developed for a specific application with a negative transmission ratio in the interval between -20 and -21. 72 valid combinations of component PGTs ideal torque ratios have been developed for this configuration, from which kinematically feasible combinations providing minimal dimensions and maximum efficiency within the required interval have been selected. The minimal dimensions of the PGT were achieved with a cylindrical case shape, i.e., with the ratio of the ring gears reference diameters close to unity. Nine other PGT configurations have been synthesized for the same transmission ratio, and their design parameters optimized. The two solutions that offer the most improvements over S13WN have been developed into design concepts.

This paper deals with configurations of complex planetary gear trains consisting of two planetary gear trains of basic type. These gear trains are formed by linking shafts from different component gearsets and contain two carriers, and therefore designated as two-carrier planetary gear trains with four external and two coupled shafts. The structural configurations are pointed out, and additional research has been made into gear trains using coupled external shafts for torque input and output, with the controlling brakes acting on single external shafts. The kinematic schemes have been created for all analyzed PGT variants, and the available transmission ratio ranges calculated for both speeds. The transmission ratio is changed by alternating the activation of each brake, enabling their use as transmissions with two transmission ratios in transportation technology and other engineering applications. Extreme transmission ratio changes have been determined for each analyzed PGT design solution. Also, relations of ideal torque ratios to the required transmission ratios of component planetary gear trains for both speeds have been calculated. These relations enable the selection of compound gear train designs which will achieve the required pair of transmission ratios. The optimal design parameters for the adopted configuration were determined, and the optimal transmission solution for the given input data selected.

The following paper reviews all the possible cases of coupled two-carrier planetary gears with four external shafts. An emphasis is made on the work of these gears with one degree of freedom, one input and one output shaft and brakes on the other two shafts . When switching over the gears, the speed ratio of the gear is changed, thus allowing the use in two-speed mechanical transmissions of technological lifting and other machines. Some relations are deduced for determining the speed ratios and the efficiency of all structural schemes. Recommendations for the selection of the most appropriate structural scheme according to the current necessities can be made. A 3D model of the S13V3 two-speed, two-carrier gearbox was created to demonstrate the process of determining the viability of a particular gearbox layout.