The invention refers to a piston assembly for a radial piston hydraulic motor. The olefin feed stream contains at least one C2 to C12 olefin to obtain an olefin feed stream and has less than 1,000 ppm by weight oxygenated hydrocarbon. In addition, the system comprises a noise processing module for isolating the induced signal for each frequency band over the range of frequency bands. A protective cap is removably coupled to the mating end of the housing. The first correction value is used for correcting a conveying amount when the recording medium disengages from a first conveying roller, and the second correction value is used for correcting the phase of the first conveying roller and a second conveying roller when the recording medium disengages from the first conveying roller before the recording medium is nipped by the first conveying roller.