Power Transmission Engineering Magazine
www.powertransmission.com/articles/2983

ZF's Right-Angled Gearheads Open Door for Luxury Multimedia Pod

May 24, 2007
The SWG gearheads from ZF offer a smoother alternative to screwjack-based door control systems used in the latest luxury media experience—the Oculas 2.0™. Designed by Lee McCormack and engineered by McLaren Applied Technologies, the Oculas 2.0™ is a multimedia product that provides users with a completely immersive environment. Uses include entertainment purposes or business applications. ZF supplied SWG gearheads to Mitsubishi Electric UK for the door operating system because of the choice of backlash options, which offered additional safety with anti-backdrive operation. The futuristic pod provides highly advanced immersive branding, conferencing, purchasing, downloading, gaming, music, film, simulation and general entertainment experiences. A single upward-swinging, gull-wing door is one of the main features of the Oculas 2.0™, and its smooth operation is essential, explains the designer. The McLaren engineering team faced initial problems with the screwjack-based door control system. “Opening and closing operations were functional, but when the 16- kilo door was lowered, the screwjacks caused a juddering motion that wasn't ideal, so Mitsubishi Electric UK was asked to specify a more effective solution,” says McCormack. The ideal door operating system would be based on a lightweight, high-ratio gearbox of the kind used in precision automation and packaging systems. However, these gearheads have traditionally been prohibitively costly for use in even luxury consumer applications. Mitsubishi Electric then approached ZF to specify the SWG range of gearheads, which offers machine builders the choice of backlash levels of more than 10, 3 and 1 arcmin,” explains Dave Morgan, technical sales engineer at ZF Great Britain. “The SWG90 right-angled gearheads were specified with levels of backlash to more than 10 arcmin, offering many of the operational benefits of a higher precision gearhead at approximately one-third of the cost.” SWG80 units have a 90:1 ratio, thereby providing a smooth door motion. Their precision high gearing eliminates backdrive, ensuring that—in the event of power or system failure—the door does not drop down, trapping or injuring the user. The gearhead design performs under high radial loads, a feature which has made the units suitable for handling systems and machine designers and, ultimately, insures the immediate stopping of the door, despite the high moment of inertia caused by the offset door pivot. SWG gearheads are designed for maximum mounting flexibility. The standard flanged model attaches directly to the Mitsubishi electric motor. The hollow shaft and shrink disc option also allow easy fitment to the output, which in this case was the Oculas 2.0™ door spindle. In addition, sealed-for-life lubrication enables the gearboxes to be mounted at 45° in the main body of the pod. According to ZF's press release, the lightweight aluminum/magnesium body of the gearhead helps reduce the final weight of the Oculas design and a computer-optimized worm wheel contact pattern offers performance level of approximately 55 dB. The pattern achieves 90% contact during operation, distributing loads evenly and contributing towards the highly rigid performance. Due to ZF's specifying two sets of oversized taper roller bearings in the SWG design, the gearwheel and spindle can also transmit higher loads with an improved degree of rigidity and accuracy.