This 40Cr steel 22T motor gear is an RC-scale pinion intended for small electric motors that use a module 0.5mm gear mesh. The hardened black surface treatment improves surface hardness and increases wear resistance under typical model power loads, while the round motor bore is sized for a 2.2mm motor tooth diameter.
Installation notes: the gear fastens to the motor shaft using two 3x3 set screws, and the round hole fits motors that match the specified shaft and tooth diameter. To ensure reliable engagement confirm the module 0.5mm pairing with your spur gear and that the 22T tooth count is compatible with your gearbox geometry before fitting.
Tuning role: this pinion is useful for drivers wanting a compact, wear-resistant option to adjust final drive ratios in electric RC models; swapping pinions with the same module and motor tooth diameter allows tuning of acceleration versus top speed without replacing motor or spur gear parts.