Gear housing

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3D partial transparency animation graphics of a single-stage gear transmission in a transmission housing
A gearbox with the upper part removed

A gear housing (or gear box ) (English. Case for a mechanical transmission) is a housing for receiving a gear . Its task is to guide existing shafts over the bearings and to grant the wheels (possibly cam disks) those degrees of freedom under all loads that they require without hindering their rotary and possibly path movement, as well as absorbing bearing forces and support torques. Depending on the type of transmission to be accommodated (e.g. gear transmission , friction wheel transmission , belt transmission , hydrostatic , hydrodynamic transmission , cam disk transmission , etc.), transmission housings can be designed and implemented very differently. Gear housings can be single or multi-shell, that is, undivided or divided. (In the case of undivided gear housings, large bores are provided in the housing for the entry of wheels and bearings; this is used, for example, in gear motors ).

Gearboxes usually have a complex shape and are often cast , but less often welded . The housing must help dampen noises and vibrations and be able to safely absorb lubricant . The lubrication of the wheels and bearings can be carried out as splash lubrication in an oil bath or as grease lubrication (the wheels of belt and friction gear drives, which remain unlubricated, are an exception to this). The lubricants used are lubricating oil , hydraulic oil or lubricating grease , for which appropriate devices are integrated in the gearbox housing. The gear housing also has to protect the wheels (possibly cam disks), bearings and lubricant against dust, water and other foreign matter. Sealing elements such as shaft sealing rings and O-rings are used to prevent lubricant from escaping from the gearbox housing .

With regard to the choice of materials for gear housings, lamellar gray cast iron is widely used for gear drives ; Graphite cast and cast steel can be an alternative. Housings for vehicle transmissions often get light metal - cast alloys , such as in magnesium - silicon - or aluminum basis used, as this is about the VW Beetle has been applied.


  • G. Niemann, H. Winter: Machine elements. Vol. 2: Transmission in general, gear transmission basics, spur gear transmission. Springer, Berlin 1983 (2nd edition), pp. 294-301.

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