Bevel gears are gears where the axes of the two shafts intersect and the tooth-bearing faces of the gears are conically shaped.  They are designed to transmit mechanical power and motion between intersecting axes.  You will most often see them mounted on shafts that are 90 degreees apart.  Metal bevel gears can be made of cast iron, brass, bronze and steel where plastic gears will be made of acetal, nylon and polycarbonate.  Special tip when placing your order would be to know the bore diameter, gear center and shaft diameter.

Helical gears unlike the bevel gears transmit power and motion between parallel axes or right angle axes. Helical gears can be mounted on a hub or shaft.  Mounting can include set screws, keyway, split or simple bore.  Special tip when placing your order would be knowing power transmission requirements, noise and heat generation and if they will be exposed to corrosive elements.  This will help to determine whether metal or plastic be chosen for your application.

Spur gears have a cylindrical pitch surface and teeth that are parallel to the axis and are used for tranmitting power between shafts.  They are used for speed reduction or increase, resolution and torque duplication.  They can also be made of plastic or metal compounds depending on the environment of the application.  Special tip when choosing the correct spur gear would be the pitch or tooth spacing of the application.

Worm gears are cylinder type gears with a spiral thread that drives the worm wheels in gearset applications.  A worm gear can provide both speed reduction and torque multiplication in smaller designed applications or packages.  They are also available in metal or plastic depending on your application.  Special tip when ordering would to know the number of teeth, gear hand direction (right or left) and face width.