US Patent 6857983 First stage clutch

A clutch assembly for limiting a torque output of the power tool. The clutch assembly includes an annular rotatable clutch member, which is coupled to the ring gear of a planetary gearset in a transmission, and an engagement assembly. The clutch member has a clutch face with a predetermined clutch profile. The engagement assembly has at least one follower member that abuts the clutch member and cooperates with the clutch profile to inhibit rotation of the clutch member relative to the follower member only when the magnitude of the torque output of the power tool is less than a predetermined maximum torque. The clutch face on the clutch member is located between the opposite axially ends of the ring gear.