Chain saw

A Chain saw, comprising:

• a housing;
• a sprocket wheel provided in the housing for driving a saw chain;
• a chain guide for guiding the movement of the saw chain, the chain guide extending out longitudinally from the housing and being movable longitudinally relative to the housing;
• and
• a chain tensioning device,
• wherein the chain tensioning device comprises a driven member arranged on the chain guide, a driving member which drives the driven member to move the chain guide longitudinally, a rotating device configured to rotate the driving member, and a stepless clutch device arranged between the rotating device and the driving member,
• wherein the stepless clutch device is a friction clutch which comprises a first elastic component providing friction pressure and a friction plate subassembly biased by the first elastic component, and
• wherein the stepless clutch device is configured to be movable relative to the rotating device, and a second elastic component is disposed between the rotating device and the stepless clutch device and the friction pressure is independent of the second elastic component,
• wherein the friction plate subassembly comprises at least one friction plate, a rotating sleeve being sleeved on a periphery of the at least one friction plate, and a friction plate base being driven to rotate by the at least one friction plate, the friction plate base connects the driving member with the at least one friction plate, the first elastic component is disposed between the friction plate base and the at least one friction plate, the driving member is configured as an eccentric wheel, and the driven member is configured as a mounting stud fixed on the chain guide.