US Patent 7257898 Cutting head for string trimmer

A cutting head for a string trimmer is provided which accommodates any string gauge thickness and may be easily and quickly re-threaded upon failure of a string previously disposed therein. The cutting head has spring-biased clamping members which are each mounted within a rotatable clamp housing within the head, such that, as a string encounters a solid object, the clamping member and its associated housing are rotated about a generally vertical axis so as to obviate or minimize the development of a stress concentration in the string in the vicinity at which it is engaged by the clamp housing.