Abstract: An improved fluid energy translating device of the axial piston type includes a cylinder barrel mounted on a drive shaft. The cylinder barrel is rotatably coupled to the drive shaft through a splined connection which includes crowned male splines on the drive shaft and female splines within the cylinder barrel. A port plate having inlet and outlet passages abuts one end of the barrel and intimate contact therebetween is maintained by a plurality of disk or Belleville springs operably disposed between the drive shaft and the cylinder barrel.

Abstract: An improved fluid pressure energy translating device of the axial piston type including a cylinder barrel mounted on a drive shaft. The cylinder barrel is centered on the drive shaft by a crowned bearing on the drive shaft and coupled through a splined connection which includes crowned male splines on the drive shaft. The crowned bearing and the crowned male splines on the drive shaft have centers located to either side to the center of bending of the drive shaft under load so as to eliminate tilting of the barrel.

Abstract: A hydraulic pump or motor device comprises a rotatable barrel containing a plurality of coaxially aligned pistons operably connected to an adjustably inclinable swash plate. The barrel is connected to a drive shaft through a concentrically disposed torque tube having two pairs of splined couplings which each incorporate a spherically profiled male spline element. In operation, the swash plate, barrel and drive shaft are subjected to unbalanced reaction forces concentrated in the semicircle of barrel rotation corresponding to the pumping strokes of the pistons. These unbalanced forces cause bowing or radial deflection of the drive shaft which is compensated by the motion freedom of the spherically splined couplings.