Swing Motor Unit is the hydraulic motor that turns the upper part of our excavator. We bolt it to the swing device and feed it oil under pressure, so the cab and boom swing smoothly. It has a strong housing and piston inside, all sealed tight to keep dirt out. When we push oil in, it rotates a shaft, and when we let oil flow back, it stops gently. We maintain it by checking oil and seals, so it never gets stuck. It makes rotating feel natural, no drama.