Precision planetary gearheads from ZF Great Britain provide high levels of torque for Cambridge University’s new radio telescope installation, which were designed for the earliest detection of galaxy clusters. According to the company’s press release, the gearmotors were incorporated into the drive system in five stages and a final drive pinion was arranged to a slewing ratio of 5.5:1. This was done to achieve the required reduction ratio of 100,000:1. The selected servo motor was geared down into two close coupled dual stage 70:1 planetary gearheads. The PG units were used primarily because they offered backlash levels of less than 2 arc minutes and a high degree of torsional rigidity. PG gearheads use grease as a lubricant and can be mounted in any orientation on the equipment.