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Crowned Tooth Gear Couplings Explained


The mechanical components that connect the ends of two shafts are called couplings or gear couplings, with one of the most interesting designs being the crowned tooth gear coupling. This type of coupling features crowned teeth on the outside of the hub which acts as an additional external gear.

A major part of any coupling’s job is to eliminate or minimise any misalignment between the two shafts. Such misalignments often occur during operations due to the movement of the application and any subsequent vibrations, shocks or impacts.

How to Make Crowned Tooth Gear Couplings

To create the crowned teeth on the hub of a crowned tooth coupling requires a gear manufacturing process called hobbing. This gear hobbing process is very popular in the gear manufacturing industry as it is quick and inexpensive, as well as very versatile allowing for mass production of multiple gear variants.

Hobbing involves the use of an automated hobbing machine (or hobber) that can come in a wide variety of sizes. The common hobber works by skewing a spindle mounted with the hob into another spindle mounted with a blank work piece. The angle of skew is determined by the type of gear being produced, and various other features will be used depending on if the gear being created is helical, straight, straight bevel, face, worm or indeed a crowned tooth gear coupling.

The two spindles are rotated on their shafts at a relevantly proportional ratio which then determines how many teeth will be hobbed into the blank work piece. For very large gears, the blank work piece is often cut to the rough shape of the final product to make the hobbing machine’s life a bit easier.

There are two main models for manufacturing crowned tooth gear couplings, namely the profile-shifting and the two-parameter enveloping methods, as explained briefly below.

Crowned Tooth Gear Coupling Manufacture

The main method for manufacturing crown teeth couplings uses the diameter of the hob and the magnitude of tangential, radial, and axial feeds to determine the shape of the crowned tooth surface.

Before beginning the manufacturing process, the load carrying capacity of the final gear coupling must be known so a theoretically ideal surface size and shape can be calculated. This method enables the spirally curved tooth surfaces to have variable profile shifts while maintaining parallel transverse planes.

The two-parameter enveloping method is an alternate manufacturing process which involves the crowned tooth surface being generated by two independent parameters: a moving ‘generating’ surface and a static ‘normal’ surface.

If you require crowned tooth gear couplings or any other parts for industrial or agricultural equipment, then contact YB Components who are the UK’s leading crowned tooth gear coupling suppliers who keep local stocks ready to ship out fast and free all over the UK and the rest of the world.