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Gears or no gears?
As torque and speed converters gearboxes are a central component in the power train. But they are not always necessary. In a direct drive the motor and gear output shaft are directly connected. In this configuration the motor design is optimally adapted to the rotational speed – which eliminates the necessity of a mechanical component for transmission of torque. Direct drives are regarded as highly dynamic, stiff, precise and reliable and have become the standard in machine tool manufacturing. The innovative technology is also used in other industries. However, direct drives consume a great deal of energy and must be water cooled whenever high inertial forces need to be moved. This makes them suitable for use in robotics primarily in applications involving extremely low torques, such as exoskeletons or hand prostheses. With respect to issues such as CO2 footprint, energy efficiency, complex assembly tasks and cost optimisation, the limits of direct drives soon become obvious. Technologies such as cycloidal gears from Nabtesco are therefore a much more attractive choice in many applications, both technologically and economically.
Cycloidal design boosts efficiency
Cycloidal gears use cams and rollers for power transmission. This ensures high efficiency, a long life and extremely low backlash, with a hysteresis loss between 0.5 and 1 arcmin, at the most. In addition, their special design achieves excellent behaviour with respect to dynamics, load capacity and smooth operation. The gearboxes perform flawlessly even in high-precision positioning applications with heavy loads or very fast and abrupt motions. The integrated angular ball bearings absorb both axial and radial loads and bending moments, and provide for high torsional stiffness and resistance to impacts and overloading (up to 500% of the rated torque). In addition, the lightweight design ensures applications with lower inertia, improved load conditions and reduced power consumption.
Cycloidal gears are clearly superior to direct drives in many applications
Their outstanding properties – high precision throughout the entire life cycle, high torsional stiffness and high reduction ratios – make Nabtesco gears a real alternative to direct drives. Direct drives require a high investment on the part of the customer (due to the high purchase price and maintenance costs) and also have a high requirement for resources such as electrical energy. Cycloidal gears are not only less expensive and easier to integrate, but also reduce energy consumption and require less installation space. And in view of changing requirements, i.e. for more compact and lightweight machine tools, cycloidal gears are the technology of choice.