Patent ID: 8528326

Claim:
A system comprising: an elongated shaft having a central axis; a first and second ratchets coupled to the shaft, each operable to apply torque to the shaft in substantially the same direction such that the shaft rotates about the central axis; an elongated pull-rod coupled to the first ratchet at a first pull-rod end; an elongated push-rod coupled to the second ratchet at a first push-rod end; a tank operable to hold a volume of fluid; a float disposed within the tank operable to float within the volume of fluid at a float-level, the pull-rod and push-rod being coupled with the float at a second pull-rod end and a second push-rod end respectively; and a displacement chamber disposed within the tank, the displacement chamber having a first cavity-portion wherein the fluid is operable to communicatively reside, and a second cavity-portion wherein a second fluid volume is operable to reside, the second fluid having a lower density than the first fluid.