guǒ
grease-pot under a cart

CEDICT

  1. (historical) grease pot hung under axle of cart
  2. (obsolete on its own in Standard Chinese) spinning; revolving (especially of wheels)
  3. grease pot hung under axle of cart
  4. spinning; revolving (especially of wheels)

Wiktionary

用來使車軸潤滑容易運轉

重編國語辭典