GEARBOXES Using a large motor as a direct drive solution is seldom economic in terms of system efficiency and space. The use of gearing to adapt motor to load enables an optimised drive solution to be obtained. The most common gearbox types are spur and planetary. Spur Gearboxes are especially advantageous in applications requiring lowest input friction and highest gear efficiency. Battery-operated or portable equipment where supply current may be limited are good examples. In-line and offset versions are available in a wide range of ratios. The design of a planetary gearbox enables a high ratio to be utilised in a single stage with the result that torque transmission is maximised and gearbox size minimised. Therefore, planetary gearboxes really come into their own when the requirements are highest rated torque in the smallest package.