Abstract: A hand held power tool, particularly a hammer drill has a housing, a drive shaft, a rotatable tool holder, a safety coupling provided between the drive shaft and the tool holder, and a switching member supported with a bearing axis extending substantially parallel to the drive shaft and freely movable about the bearing axis in a plane extending substantially perpendicularly to the drive shaft. The switching member during a rearward rotation of the housing about an axis of the tool holder engages in the safety coupling and releasing the safety coupling.

Abstract: Screw joint tightening power tool, comprising a rotation motor (13), a power control (34), and a torque responsive override clutch (15) coupling the motor (13) to an output shaft (16). A power control (34) actuating mechanism is associated with the clutch (15) and comprises a push rod (36) which in an ON-position rests axially against a transversely movable latch (41) and is released for axial displacement toward an OFF-position at relative rotation between the driving and driven halves (20, 22) of the clutch (15). The actuating mechanism further comprises balls (45) which are disposed in peripheral pockets (48) in one of the clutch halves, either of which balls (45) is arranged to cooperate with the latch (41) to shift the latter to a push rod (36) releasing position to, thereby, make the power control (34) shut off the power supply to the motor (13) as the clutch (15) overrides at a desired torque level.

Abstract: A valve construction for dual valve automatic and manual shut-off screwdrivers and the like wherein construction of the valve features both valve elements in a central axial bore having a unique valve block which is held in place by a screw in a transverse bore, the unique construction permits operation of the manual valve by a pin in the cross bore, aligns the stem of the manual valve, and permits ready access to the stem and valve of the automatic shut-off device as well as assembly of all of the components through access in a single longitudinal bore.

Abstract: An improved torque control and fluid shut-off mechanism for a fluid operated tool includes a driving clutch member and a driven bit holder connected by ball bearings retained by the clutch member which engages in pockets in the bit holder. The pockets include a specific ramp construction which insures that the threshold torque level of the tool in the forward direction is less than the threshold level in the reverse direction.

Abstract: A power tool includes a DC motor for tightening a fastener through three consecutive stages. In the first stage, the motor is rotated at a high speed to tighten the fastener to a pre-seated condition which is acknowledged by the tool. Then, the motor is temporarily stopped and restarted at a low speed for tightening the fastener to its seated condition to complete the second stage. At the third stage, a control is made to gradually increase a field current in a feedback manner by constantly monitoring the field current flowing through the motor up to a predetermined current limit determined as directly related to an intended tightening torque at which the fastener is tightened past the seat condition. After the field current reaches the current limit, the motor is stopped to complete the tightening cycle.

Abstract: A screw tightening power tool, comprising a rotation motor, a power supply (27) connected to the motor, an output shaft (13), a torque responsive release clutch (14) including a driving half (16) and a driven half (17) and coupling the motor to the output shaft (13), an activating rod (26) coupled to the power supply (27), a latch means (24) associated with one of the clutch halves (16) and cooperating with the activating rod (26), and a cam (30) associated with the other of the clutch halves (17) and operatively connected to the latch (24) for making the latch shift from an activating rod (26) supporting position to an activating rod (26) releasing position as the transferred torque has reached the actual preset release torque level of the clutch. The cam (30) comprises a spindle (30) which is rotatively supported relative to the driven clutch half (17) for a limited rotational movement relative thereto.