What is a spur gear?

Spur gears are the most easily visualized common gears that transmit movement between two parallel shafts. Because of the shape, they are classified as a kind of cylindrical gears. Because the tooth areas of the gears are parallel to the axes of the mounted shafts, there is no thrust force produced in the axial direction. Also, because of the simple production, these gears can be made to a higher degree of precision. On the other hand, spur gears possess a disadvantage in that they very easily make noise. In most cases, when two spur gears are in mesh, the apparatus with more teeth is named the “gear” and the main one with the smaller number of teeth is called the “pinion”.

The unit to indicate the sizes of spur gears is often stated, as specified by ISO, to be “module”. Recently, it is usual to set the pressure angle to 20 degrees. In commercial machinery, it really is most common to employ a portion of an Gear rack involute curve as the tooth profile.

Even though not limited by spur gears, profile shifted gears are used when it is necessary to adjust the guts distance slightly or to strengthen the equipment teeth. They are made by adjusting the range between your gear cutting device called the hobbing device and the apparatus in the creation stage. When the shift can be positive, the bending power of the gear increases, while a poor shift somewhat reduces the guts distance. The backlash is the play between the the teeth when two gears are meshed and is needed for the clean rotation of gears. When the backlash is too big, it leads to increased vibration and noise as the backlash that’s too small leads to tooth failure because of the lack of lubrication.

All KHK spur gears have got an involute tooth form. Put simply, they are involute gears using part of the involute curve as their tooth forms. Looking generally, the involute form is the most wide-spread equipment tooth form due to, among other factors, the capability to absorb small center distance errors, quickly made production equipment simplify manufacturing, heavy roots of the teeth make it strong, etc. Tooth form is often described as a specification in drawing of a spur gear as indicated by the elevation of teeth. In addition to standard complete depth teeth, extended addendum and stub tooth profiles exist.