CHAIN SAW

摘要

A chain saw (5) comprises a shell (6), a sprocket wheel (7) which is provided in the shell (6) and is used to drive a saw chain (11) and a chain guide (9) for guiding the movement of said saw chain (11); said chain guide (9) extends out longitudinally from the shell (6) and can move longitudinally relative to the shell (6); said chain saw (5) comprises a chain tensioning device which comprises a driven member arranged on said chain guide (9) and a driving member which drives said driven member, which in turn drives the chain guide (9) to move longitudinally, and a rotating device (15) which is used for rotating said driving member; a stepless clutch device is arranged between said rotating device (15) and said driving member. The chain tensioning device of the invention can lead the chain saw (5) to press the chain guide (9) when tensioning the saw chain (11) and can prevent effectively the chain guide (9) from loosing after the saw chain (11) is tensioned, the operation of the chain tensioning device is labour-saving, the structure is stable, and it is not easy to be worn.