The 12” solid, driveshaft rotor “broke off” a 20,000 lb cooker of chicken feathers at a remote, rendering plant. The final fracture surfaces were smooth and rippled with classic fatigue features. Prior to failure, the shear pin broke during a lock up, however, the cooker assembly continued to rotate. The rotor was a forging with a long driveshaft and pillow block bearings that supported the end of the cooker. The forging was welded to the flat cooker vessel head. It was reported that the cooker rotated erratically during final days of operation. The pillow block bearings were small, damaged and fragmented.