Gearboxes Explained

A Gearbox (or Transmission, for our American cousins) can be a gear or hydraulic based system that transfers mechanical power from an engine or motor to an output device which will perform the required function.

Gearboxes are found in all walks of life, from household tools and kitchen appliances to cars, aircraft, mining and industrial equipment, though most people probably don’t realise they came across a gearbox at a very young age, on their first bicycle. Early gearboxes were used in windmills and various steam engines too, driving a variety of agricultural machinery.

A simple gearbox would have just two gears, forwards and backwards, achieved by changing the direction in which the power is transmitted. In a more complex gearbox the speed of the input shaft would be changed.Beyond that, a gearbox would come with gear ratios (normally just referred to as gears), so the torque and/or output speed can be increased or decreased at will. This can be of help when a gearbox may be required to slow down and speed up at will, like a car. Modern gearboxes are usually used to increase torque while reducing the speed of a prime over output shaft, though they can be set to do the opposite.

Bearings play an important role in gearboxes and they’ve contributed considerably to developments in increasing efficiencies in regards to the gear-weight/driving-torque ratio. There are a variety of bearing types used for gears including deep groove ball bearings, cylindrical roller bearings and tapered roller bearings to mention just a few. Different industries require different criteria in terms of the bearings used in gears as they need to meet with specific requirements so these should be discussed with the bearing suppliers. For example, bearings for industrial gears need to have a simple design, high efficiency and require minimum maintenance. Whereas bearings for machine tool gears place the importance on high precision, rigidity and the ability to operate at high speeds. So it’s important to find bearing suppliers who can offer the right bearings for the right gears and purpose.