Pfaff-silberblau at Hannover Messe 2007, Hall 26, Booth H27

Focus on Satellites: Precise Polar-Mount Antenna Positioning from Pfaff-silberblau

The ALSR 100’s tailored actuator design with electromechanical screw rams ensures exact elevation and azimuth movements.

Friedberg, Germany, April 16, 2007 – Moving heavy objects with utmost precision is no doubt one of the core areas of expertise for Pfaff-silberblau Hebezeugfabrik GmbH & Co. KG of Derching/Friedberg, Germany. In a recent project for a well-known institute, Pfaff-silberblau’s engineers once again demonstrated their tremendous proficiency in developing individualized designs. Using electromechanical screw rams from the company’s own “building-block” modular system, they developed polar-mount positioning capabilities for precise adjustment of a satellite receiver antenna that weighs in at 8 tons and has a diameter of about 5 meters. The antenna, which has the task of perfectly tracking geopolar satellites travelling in an elliptic orbit around the earth about 37,000 km above the equator, requires ultra-precise positioning capabilities that enable it to perform both tilting and swivel movements. Pfaff-silberblau achieved this coupling of elevation and azimuth movements in a polar-mount configuration on the basis of three completely encapsulated electromechanical screw rams in the ALSR 100 size with robust axial and radial bearings. One electromechanical screw ram ensures highly accurate positioning of the vertical angle of elevation, while the second system, which consists of two ALSR 100s, sets the horizontal azimuth angle. Integral, reinforced swivel journals enable the antenna to swivel to the prescribed angle position in both the elevation and azimuth directions. Despite the heavy load, the equipment travels a maximum stroke of 450 mm at a speed of around 130 mm/min. The travel limits are monitored via two built-on inductive proximity switches. Both electromechanical screw rams are driven via a motor reduction unit with a built-on absolute value transmitter, and they are actuated using a frequency converter. Pfaff-silberblau’s drive concept includes a comparison of the target data with the actual data, the motor’s rotational speed, and a master/slave synchronisation of the two individual actuators for the azimuth movements. In this way, the drive motor’s rotational speed can be measured via the built-on sensor, and the resulting value can then be fed back to the speed controlling device, which minimizes load-dependent deviation. Simultaneously, the master actuator supplies the encoder signals to the slave actuator as the target value. The slave then compares this data with the signals from its own actuator, and readjusts as necessary. The antenna positioning system from Pfaff-silberblau is not only precise, it is also robust: Thanks to the electromechanical screw ram’s self-locking trapezoidal spindle, independent positioning of the antenna is even possible in windy and stormy conditions. Still more exciting solutions from the realm of actuator technology as well as such equipment as powerful worm-gear screw jacks, electromechanical linear actuators and electromechanical screw rams are being presented by Pfaff-silberblau at the Hannover Messe 2007 in the “Motion, Drive & Automation” exhibition area in hall 26 at booth H27.

About Pfaff-silberblau Founded 140 years ago, Pfaff-silberblau, with headquarters in Derching/ Friedberg, Germany, employs 325 people, and has a group turnover of approximately € 61 million (business year 2006). Pfaff-silberblau one of the leaders in technology for lifting gear and drive technology. The company is a competent partner for all solutions involving the moving (turning, lifting, lowering, pushing, shifting) of loads up to 1,000 t in all directions. Pfaff-silberblau has their own manufacturing plants in Derching/Friedberg and Heilbronn, and have their own national companies in Switzerland, Austria, England, Benelux, Poland and Hungary. In addition to these, more than 40 affiliated agencies and representatives are active for Pfaff-silberblau and their customers worldwide.