This rear straw-walker shaft transmits oscillating motion to the walker assembly, which separates grain from the material mat as it moves rearward through the threshing unit. It connects the drive mechanism to the walker cranks, converting rotational input into the lifting and dropping action that conveys straw toward the exit. A worn or bent shaft causes uneven walker timing, leading to incomplete separation and increased grain loss over the sieves. The shaft is machined to match the original geometry so that the bearing bores and crank arms align without shimming. On installation, verify that the shaft rotates freely in its bearings before connecting the drive linkage.