Abstract: A string trimmer providing an incremental indexing of line when the head is stopped and started. The preferred embodiment of the string trimmer head includes a spool member within the body member, the spool member being coaxially positioned within the body member and being rotatable therewith. The spool member includes a grooved end face with a cam channel having at least one switchback and one arcuate segment. A connecting means attached to the body member includes a connector which runs within the cam channel. Upon starting the rotation, the connector runs along an arcuate segment of the cam channel (permitting relative rotation between the spool member and the body member thereby indexing a length of line) until contacting a switchback stopping point. The connector is biased to move along the switchback and resets along the switchback upon stopping of rotation.

Abstract: A string trimmer providing an incremental indexing of line when the head is stopped and started. The preferred embodiment of the string trimmer head includes a spool member within the body member, the spool member being coaxially positioned within the body member and being rotatable therewith. The spool member includes a grooved end face with a cam channel having at least one switchback and one arcuate segment. A connecting means attached to the body member includes a connector which runs within the cam channel. Upon starting the rotation, the connector runs along an arcuate segment of the cam channel (permitting relative rotation between the spool member and the body member thereby indexing a length of line) until contacting a switchback stopping point. The connector is biased to move along the switchback and resets along the switchback upon stopping of rotation.

Abstract: A powder-actuated fastening tool is provided with a firing mechanism which permits the powder cartridge to be fired by a hammer. The tool includes an outer housing, a piston guide slidable within the housing, and a piston slidable within the piston guide. An abutment in the housing extends through a slot in the piston guide and is engageable with the piston for moving the piston rearwardly relative to the piston guide to eject a spent cartridge and to position the piston for firing. The cartridge is mounted within a cartridge holder on the end of the piston guide, and the cartridge-firing mechanism is mounted on the end of the housing. The cartridge-firing mechanism includes a guide tube secured to the housing, a bolt slidable within the guide tube, and a spring biasing the bolt away from the cartridge holder. A cartridge in the cartridge holder can be fired by striking the bolt with a hammer with sufficient force to overcome the resistance of the spring and to cause the bolt to strike and fire the cartridge.