Internal Gear is a gear with its teeth trimmed at the inner surface of a cylinder and meshes with spur gears. Internal gears are often used in applications involving planetary gear drives and gear couplings.

An age of technology

“Internal Gear teeth cutting operation. 196 T, 9 Module , 240mm FW,260mm, Total width OD 1840,20 ⁰ Pressure angle”

There are 3 big types of planetary gear mechanics: planetary, solar and celebrity types. Based on the type and the pattern of which shafts act as input and output, many variants of speed transmission ratios and rotational directions are created.

Normally, internal gears may be used with exactly the exact same module spur gears, depending on the amount of teeth blends, but it is essential to note the possibilities of getting involute, trochoid or trimming interferences.

Also, although it is usually too expensive to make helical teeth inner gears, KHK has made it feasible to produce them by adopting equipment that may cut them by just making pinion cutters rather than having helical guides.

“As it is seen from the precision course of DIN Class at Marshall, it creates high precision gears. ”

Confident Approach

In its production, due to its shape, the customary hobbing machine employed in spur gear production cannot be used. Generally it is made with equipment shaper (or equipment measuring machine) equipped with a pinion cutter. More recently, the efficiency of internal equipment cutting was improved by a different process called skiving.
As it is seen from the precision course of  DIN Class at Marshall, it creates high precision gears. On the flip side, gear grinding to improve precision grade is limited by the amount of manufacturers and their available grinding facilities resulting in very large cost. And most of the times the application of these gears don’t need grinding.