New servo motor is a 'hole' lot better

Dean Palmer reports on a new servo motor that offers reliability, compactness and a much greater bore size than other hollow shaft motor currently on the market A hollow shaft motor has been launched which, according to its developer, is more compact than competing alternative motors and has a significantly greater bore (up to 40mm) than conventional hollow shaft motors. The firm responsible for the new motor is Swedish company HDD Servo Motors. Rolf Ohlsson, head of marketing at the company told Eureka: "The motor is a reliable solution for applications where liquids, coolants, cables, tools or rotating shafts need to pass through the rotating motor shaft, and where very small installation dimensions are required." Tools or other equipment driven by servo motors often need cooling or an electric power supply. The use of conventional servo motors with a solid shaft often calls for complex, costly solutions, because hoses or cables need to be run around the driving motor. The cost gets even higher where a separate rotating shaft with the same centre location as that of the servo motor is required. Ohlsson continued: "A hollow shaft motor in which hoses, cables and rotating shafts can be passed through the servo motor's own shaft provides a far cheaper and simpler overall solution with fewer components, which in turn, gives a more reliable solution." According to Ohlsson, the motors are also suitable for driving ballscrews, since the ballscrew can pass through the large bore of the hollow shaft. "The electromechanical design of the hollow shaft motor is based on our patented 'Stritorque' technology," explained Ohlsson. "This allows very compact servo motors with low heat dissipation and a torque/volume ratio of as much as 6.8Nm per litre. The motor doesn't need any new drive electronics - most modern drive systems can be used. The hollow shaft can be customised and provided with threads, fixing holes, grooves or slots." The motor comes with a high resolution feedback system which can be single- or multi-turn. The motor is available with a 92mm flange and in three torque sizes: 2.8Nm, 5.2Nm and 6.0Nm, with lengths of 100mm, 128mm and 150mm respectively.