PNEUMATIC PULSE TOOL WITH SHUT OFF-MECHANISM

摘要

A pneumatic torque impulse delivering power tool (10) with an automatic power shut-off mechanism, the power tool (10) comprising a pneumatic motor (11); a drive member (16) which is driven to rotate by said pneumatic motor (11); an air supply channel (14) for providing the motor (11) with pressurized air; a shut-off valve (15) arranged in said air supply channel; and a valve control device (17) arranged to shut said shut-off valve (15) and stop the air flow to the pneumatic motor (11) when the drive member (16) is exposed to a retardation magnitude above a certain threshold level. The valve control device (17) comprises an inertia responsive member (18), which is arranged to rotate along with the drive member (16), and which is pivotally arranged with respect to the drive member (16) between an initial position in which it does not interfere with the shut-off valve (15) and a shut-off position in which it allows the shut-off valve (15) to close. The valve control device (17) further comprises an air damped movement restrictor (29) arranged to counteract the movement of the inertia responsive member (18) towards its shut-off position, such that the shut-off valve (15) is only shut when the drive member (16) is exposed to a retardation magnitude above a certain threshold level corresponding to a dampening force of the air damped movement restrictor (29). A spring (35) may be arranged inside the air damped movement restrictor (29).