Positioning system GGT 90. The GGT 90 positioning system is a low cost spindle axis system for wheelchair and other lifting applications. Any motor can be used to drive this very durable and reliable product. It is based on a corrosion proof square aluminum profile with 90 mm edge length. The system’s carriage is moved by a rotating thread spindle with a guide nut. An optional stop nut can be added for extra safety in case of damage to the guide nut. A PE band enforced with tear resistant steel mesh tightly covers the guide element openings to prevent injuries as well as to protect the interior from dirt.