Example 2: Sprocket Locking Device Failure.(Ref 33). A design deficiency involving improper materials selection was revealed through the analysis of a failed tapered-ring sprocket locking device. The device is used to attach a chain sprocket to a shaft without the use of a locking key, enabling the shaft to either drive or be driven anywhere on the shaft (see Fig 9). The configuration consists of an assembly of four tapered rings(Fig. 10) that are retained by a series of cap screws. As shown in Fig. 11, when the screws are tightened, the middle wedge-shaped rings are pulled closer, forcing the split inner ring to clamp tightly onto the shaft, and the split outer ring to force tightly against the inside diameter of the sprocket. When properly assembled and torqued, the sprocket is fixed to the shaft ocking device Fig 9 Sketch of tapered-ring locking device application Occ Fig. 10 Four tapered rings of locking device. Arrow indicates crack in one of the middle Ings. Cap Outer ring screw ⑥ ring O6⑩ Fig. ll Plan view (left) and cross section (right) through tapered-ring locking device assembly During initial assembly of a new locking device by the manufacturer during a bench test, one of the wedge-shaped middle rings fractured prior to having been fully torqued, preventing the sprocket from being locked to the shaft. The failed assembly was investigated for root cause. One of the middle rings had cracked(Fig. 10, 12a). Examination of the fracture Thefileisdownloadedfromwww.bzfxw.comExample 2: Sprocket Locking Device Failure. (Ref 33). A design deficiency involving improper materials selection was revealed through the analysis of a failed tapered-ring sprocket locking device. The device is used to attach a chain sprocket to a shaft without the use of a locking key, enabling the shaft to either drive or be driven anywhere on the shaft (see Fig. 9). The configuration consists of an assembly of four tapered rings (Fig. 10) that are retained by a series of cap screws. As shown in Fig. 11, when the screws are tightened, the middle wedge-shaped rings are pulled closer, forcing the split inner ring to clamp tightly onto the shaft, and the split outer ring to force tightly against the inside diameter of the sprocket. When properly assembled and torqued, the sprocket is fixed to the shaft. Fig. 9 Sketch of tapered-ring locking device application Fig. 10 Four tapered rings of locking device. Arrow indicates crack in one of the middle rings. Fig. 11 Plan view (left) and cross section (right) through tapered-ring locking device assembly. During initial assembly of a new locking device by the manufacturer during a bench test, one of the wedge-shaped middle rings fractured prior to having been fully torqued, preventing the sprocket from being locked to the shaft. The failed assembly was investigated for root cause. One of the middle rings had cracked (Fig. 10, 12a). Examination of the fracture The file is downloaded from www.bzfxw.com