Robert Boschgmbh

Klaus-Peter Fritschi

Karl Roll

The power tool has a drive motor and a turn-on switch device activatable for turning on the drive motor. A manual activator is mounted for swinging movement in a predetermined plane of motion and in a predetermined direction from a normal position to an activating position in which it activates the turn-on switch device. The manual activator is so arranged and configurated as to be depressible in the predetermined direction by a hand of the user of the power tool. A safety device prevents unintentional activator depression and includes a blocking structure. The blocking structure is mounted for swinging movement relative to the manual activator in generally the predetermined plane and in the predetermined direction from a blocking position in which it prevents activator depression to an unblocking position in which it permits such depression. The blocking structure is comprised of one or more cooperating levers and is so configurated and located relative to the manual activator as to be depressible by a finger of the same hand which depresses the manual activator.

Power tool with device for preventing unintentional turn-on of drive

A clutch connects the drive motor to the rotatable tool holder. The driven part of the clutch has a plurality of clutch recesses bounded by sloping clutch ridges, with clutch balls received in the recesses. An annular pressure body surrounds the driving part and is pressed by a threshold-torque-determining spring against the clutch balls to hold them in their recesses. When the clutch torque exceeds the threshold value, the clutch balls rise out of the clutch recesses and slip over the respective clutch ridges into the respective adjoining clutch recesses. In so doing, they briefly push back the annular pressure body. This causes the annular pressure body to drive locking balls radially inward through registering radial openings in the driving part and in a locking bolt interior to the latter. When the inner locking ball moves completely into the locking bolt, locking between the driving part and locking bolt terminates. Then, a locking spring which previously participated in the locking action by urging the locking balls radially outward can shift the locking bolt axially relative to the driving part in a sence causing a release valve device to close and terminate energization of the power tool drive motor.

Growing community of inventors

Merklingen, Germany

Klaus-Peter Fritschi