GM38VB is a model designation used for a travel motor (hydraulic drive motor) used in construction excavators (e.g., Kobelco SK200-8 and Kato 1023-3). The GM38VB travel motor includes many internal parts needed for operation and repair.

So what servo ball is

• The servo ball isn’t a separate consumer item you would buy by itself — it’s a small spherical component inside a hydraulic motor assembly.

• Its function is to act as a precision bearing/element in the servo control mechanism of the travel motor (hydraulic actuator) to help direct fluid and motion.

Where it’s used

• These parts are used when overhauling (repairing) the travel motor of an excavator — the unit that drives the tracks and moves the machine.

If what you’re actually looking for is a standalone servo motor ball bearing or servo component for RC/robotics, let me know — I can help locate those separately!