The Collaborative International Dictionary of English v.0.48:

Chain pump \Chain" pump`\
   A pump consisting of an endless chain, running over a drum or
   wheel by which it is moved, and dipping below the water to be
   raised. The chain has at intervals disks or lifts which fit
   the tube through which the ascending part passes and carry
   the water to the point of discharge.
   [1913 Webster]