Looking for a compact internal gear for a planetary mechanism? KHK SI provides steel gears with teeth on the inside of the ring.
Customer: What is this series?
KAYO: SI is the standard steel internal gear family. Its inward-facing teeth mesh with an external pinion. KHK specifies S45C steel with cut teeth and allows secondary machining. Confirm any modification against the product drawing.
Customer: Which sizes are listed?
KAYO: The current Japanese table lists 17 models, with modules 0.5, 0.8, 1, 1.5, 2, 2.5. The table below shows every listed model and its basic dimensions.
| Model | Module | Teeth | Outside diameter (mm) | Mass (kg) |
|---|---|---|---|---|
| SI0.5-60 | 0.5 | 60 | 50 | 0.049 |
| SI0.5-80 | 0.5 | 80 | 60 | 0.062 |
| SI0.5-100 | 0.5 | 100 | 70 | 0.074 |
| SI0.8-60 | 0.8 | 60 | 75 | 0.16 |
| SI0.8-80 | 0.8 | 80 | 90 | 0.20 |
| SI0.8-100 | 0.8 | 100 | 105 | 0.23 |
| SI1-60 | 1 | 60 | 90 | 0.28 |
| SI1-80 | 1 | 80 | 110 | 0.35 |
| SI1-100 | 1 | 100 | 130 | 0.43 |
| SI1.5-60 | 1.5 | 60 | 130 | 0.81 |
| SI1.5-80 | 1.5 | 80 | 160 | 1.04 |
| SI1.5-100 | 1.5 | 100 | 190 | 1.26 |
| SI2-60 | 2 | 60 | 170 | 1.79 |
| SI2-80 | 2 | 80 | 210 | 2.28 |
| SI2-100 | 2 | 100 | 250 | 2.77 |
| SI2.5-60 | 2.5 | 60 | 210 | 3.33 |
| SI2.5-80 | 2.5 | 80 | 260 | 4.25 |
Customer: Can I use any pinion with the same module?
KAYO: Matching module is only the starting point. Check pinion tooth count, pressure angle, center distance and tooth interference. Involute, trochoid and trimming interference can limit the usable combination or assembly direction. Review KHK's mating-pinion guidance before finalizing the pair.
Customer: Where would I consider this gear?
KAYO: Internal gears are used in planetary arrangements and other compact reduction mechanisms. SI gives designers several smaller module choices for the internal stage. Suitability depends on the complete gear train, mounting rigidity, lubrication, speed and load.
Customer: What information should I send for an enquiry?
KAYO: Please send the full SI model code, quantity, mating pinion details, mounting requirements and operating conditions. We can discuss the specification and availability for your application. Manufacturer torque values depend on their stated calculation conditions and should be checked for the actual duty.
References: KHK SI official model selection table | KHK internal gear range | KHK internal gear selection guidance. Confirm final dimensions against the latest manufacturer drawing.