Motor-drive chain saw with a clutch and oil pump

A motor-driven chain saw equipped with a saw chain and a guide bar for guiding the movement of the saw chain thereon, comprising:

• a housing;
• a drive motor mounted in said housing and having a motor drive shaft;
• pump means for pumping lubricating oil for lubricating the saw chain and the guide bar;
• drive means for driving said pump means, said drive means being rotatably journalled on said drive shaft, said drive means being a drive wheel engaging said pump means for actuating the latter;
• sprocket means rotatably journalled on said output shaft for driving said saw chain around the periphery of said guide bar;
• clutch means for operatively connecting said drive shaft to said sprocket means, said clutch means including a clutch drum having a peripheral wall;
• and,
• detachable torque transmission means for operatively connecting said drive means to said peripheral wall of said clutch drum, said detactable torque transmission means including a coupling spring for transmitting torque from said clutch drum to said drive wheel, said coupling spring having a first end portion, said clutch drum being cup-shaped and having an open end face;
• said clutch drum being mounted on said drive shaft so as to cause said open end face to face toward said pump means and said drive wheel;
• said sprocket means being disposed on the side of said clutch drum facing away from said pump means and on the outer end portion of said drive shaft, said peripheral wall of said clutch drum defining first coupling spring receiving means at the region of said open end face for receiving said first end portion of said coupling spring therein.

A motor-driven chain saw equipped with a saw chain and a guide bar for guiding the movement of the saw chain thereon, comprising:

• a housing;
• a drive motor mounted in said housing and having a motor drive shaft;
• pump means for pumping lubricating oil for lubricating the saw chain and the guide bar;
• drive means for driving said pump means, said drive means being rotatably journalled on said drive shaft;
• sprocket means rotatably journalled on said output shaft for driving said saw chain around the periphery of said guide bar;
• clutch means for operatively connecting said drive shaft to said sprocket means, said clutch means including:
• a cup-shaped clutch drum connected to said sprocket means and being rotatably journalled on said drive shaft;
• and, centrifugal weight means for engaging said clutch drum and sharply accelerating the latter to a predetermined rotational speed whereby the torque of said drive shaft is transmitted to said clutch drum and said sprocket means;
• said clutch drum having a base wall defining a first plane perpendicular to said drive shaft and having a peripheral wall extending outwardly from said base wall so as to be coaxial with said drive shaft and overlap said centrifugal weight means, said peripheral wall extending outwardly from said base wall still farther so as to at least partially overlap said drive means in spaced relationship thereto;
• resilient torque transmission means for resiliently transmitting torque from said peripheral wall of said clutch drum to said drive means for rotatively driving the latter and for transmitting said last-mentioned torque so as to prevent the sharp acceleration of said clutch drum from being transmitted to said drive means thereby protecting said drive means and said pump means from excessive wear;
• and,
• said resilient torque transmission means lying in a second plane substantially parallel to said first plane thereby providing an axially compact arrangement of said drive means and said clutch drum on said drive shaft.