Blockage-protected drive system with a centrifugal clutch, and sawing apparatus driven through said clutch

摘要

To prevent overloading of a clutch interposed between a driving, or input shaft (2, 112) and a driven, or output shaft (4, 115) upon blockage of the output shaft while continuous rotary power is being transmitted to the input shaft, a plurality of centrifugal weights (16, 117) are located on an output clutch member (14, 116) so that, in case of blockage of the output shaft, centrifugal force will immediately cease and power transmitting engagement between the input and output shafts will be disconnected. In order to permit starting of the clutch, a predetermined small frictional force between an input clutch member (6, 114) coupled to the driving or input shaft (2, 112) and the output clutch member (14, 116) is established, essentially independent of speed, for example under control of springs (22). Since the power connection between the input and output shafts ceases immediately upon blockage of the output shaft, feedback of blocking force, and hence impact loading on a drive motor (14) coupled to the input shaft, and gearing and the like connected thereto is effectively eliminated. The clutch is particularly suitable for use in floor saw--power pack apparatus, power bearing tools, saws, snow blowers or the like, where blockage of the output shaft, unless instantaneously decoupled from a power drive may cause hazards, and/or apparatus damage.