Shaft load balancing system

A shaft load balancing system includes a housing divided into a first chamber at a first operating pressure and a second chamber at a second, lower operating pressure. A shaft passes from the first chamber into the second chamber. The shaft includes a first end in the first chamber, a second end in the second chamber, and a substantially axial channel connecting the first end and the second end. The first end is in fluid communication with a fluid reservoir in the housing. A reaction member engages the second end. The reaction member includes a compression volume in fluid communication with the channel. A pressure differential between the chambers forces fluid from the fluid reservoir through the channel and into the compression volume. The reaction member transmits the fluid force to the housing, allowing the fluid to create a force on the second end of the shaft. In one embodiment, the reaction member is axially movable on the shaft and rotatable with respect to the housing. In another embodiment, the reaction member is axially movable on the shaft and constrained against rotation with respect to the housing. In a further embodiment, the reaction member is fixed to the housing and restrains radial motion of the shaft. The shaft load balancing system balances pressure-induced, axial shaft loads by generating a force on the second end of the shaft that is approximately equal to the pressure-induced force on the first end of the shaft.