轮轴,车轴
Axletree \Ax"le*tree`\, n. [Cf. Icel. ["o]xultr?.] 1. A bar or beam of wood or iron, connecting the opposite wheels of a carriage, on the ends of which the wheels revolve. 2. A spindle or axle of a wheel. [Obs.]
axletree n : a dead axle on a carriage or wagon that has terminal spindles on which the wheel revolve