A lubrication system including a drive fluid chamber and a lubricant chamber. A first movable member is movable from a first position to a second position within the drive fluid chamber in response to drive fluid pressure acting on the first movable member. A second movable member is movable between a first position and a second position within the lubricant chamber and is operatively coupled to the first movable member. A biasing member is positioned to bias the first movable member toward the first position. A relief valve is associated with the first movable member and, when the relief valve in an open state, the drive fluid pressure acting on the first movable member is reduced such that the biasing member moves the first movable member to the first position within the drive fluid chamber.

A protective device at least for protecting a user in the event of an uncontrolled blockage of a portable power tool includes at least one rotationally drivable shaft and at least one wrap-spring-free overload clutch unit which is arranged on the shaft and is configured at least to interrupt transmission of a drive force if a torque limit is exceeded. The protective device further including at least one wrap-spring clutch unit configured to brake the shaft.

In an aspect of the disclosure there is provided a vibration reducing apparatus for a percussive tool having an axis of reciprocation. The apparatus comprises, a guide frame and at least one member extending across the axis of reciprocation. An assembly extending in a direction of along the axis of reciprocation comprises at least two layers and each layer comprises four interconnected elongate members pivotally attached and rotatable with respect to each other to define a polygon; and the assembly has at least one biasing means. A handle is movably coupled to the guide frame and supported on the assembly. The apparatus provides decreasing stiffness with increasing compression of the assembly under an applied load to the handle for reducing vibration in a predetermined frequency range.

The self-contained force magnifying tool disclosed herein includes a tool portion, a striker, at least a portion of which is disposed within the tool portion, and a spring, a least a portion of which is disposed within the tool portion. The spring attaches to both the tool portion and the striker. When the striker is pulled by a user, the spring stores mechanical energy. When the user releases the striker, the striker impacts on the tool portion transferring the mechanical energy stored in the spring into a driving force. The force is magnified by a tool disposed on the tool portion of the self-contained force magnifying hand tool and applied to a workpiece.

An electric power tool includes a motor, a spindle, a first vibration cam, a housing, a second vibration cam, a vibration switching member, and a plurality of biasing members. The spindle is rotatable by the motor. The first vibration cam is fixed to the spindle. The first vibration cam is located inward of the housing. The second vibration cam is located inward of the housing. The second vibration cam is configured to be in friction with the first vibration cam. The vibration switching member switches between a rotatable condition and an unrotatable condition of the second vibration cam with respect to the housing. The plurality of biasing members bias the vibration switching member.

A handheld power tool includes a tool holder for holding a tool, an electric motor, a shaft connecting the tool holder and the electric motor, and a protective device for stopping the tool holder in an uncontrolled situation. The protective device includes a sensor for detecting the uncontrolled situation, a switchable current source and a normally closing magnetic brake. The switchable current source outputs a first current not equal to zero in response to signals of the sensor if an uncontrolled situation is not detected; the current source does not output a current or outputs a second current different from the first current if an uncontrolled situation is detected. The normally closing magnetic brake engages on the shaft and does not apply a torque to the shaft when energized by the first current. The normally closing magnetic brake applies a torque counteracting the rotational movement of the shaft when not energized or when energized by the second current.

A work tool includes a motor, a driving mechanism, a body housing and a handle. The driving mechanism is configured to perform an operation of linearly reciprocating the tool accessory along a driving axis extending in a front-rear direction. The handle includes a grip part extending substantially in an up-down direction, and a battery-mounting part provided on a lower side of the grip part. An upper end portion of the handle is connected to a rear end portion of the body housing via an elastic member so as to be movable relative to the body housing. A lower end portion of the handle is connected to the rear end portion of the body housing so as to be rotatable relative to the body housing, around a rotation axis extending in a left-right direction. The rotation axis is located on a lower side of the battery-mounting part.

A hammer drive mechanism for a hammer strike mechanism of a hammer drill is provided including: a drive shaft capable of being rotationally driven by a motor, a rod capable of reciprocatingly driving a piston, and a conversion mechanism that converts the rotary movement of the drive shaft into a reciprocating movement of the rod. The drive shaft comprises a first part connected to the conversion mechanism and a second part capable of being rotationally driven by a motor. The second part connects to the first part via at least one dampener such that rotary movement of the second part is transferred to the first part via the at least one dampener.

A clutch device includes a guiding element, a first clutch element being capable of sliding relative to the guiding element, a second clutch element being capable of sliding relative to the guiding element, an elastic element including a first connecting leg and a second connecting leg which are respectively connected with the first clutch element and the second clutch element, and a rotating element being capable of rotating about a first axis relative to the guiding element. The rotating element includes a first supporting portion for contacting with the first connecting leg, which is disposed at a first axial position of the first axis, and a second supporting portion for contacting with the second connecting leg, which is disposed at a second axial position of the first axis.

A force-limiting and damping device has a body, a tapping element, an elastic element, and a reinforcing element. The body has a connecting segment with a mounting hole. The tapping element is movably connected to the body and has a mounting segment, a tapping segment, a fixing segment, and a protrusion segment. The protrusion segment is formed on a connecting portion between the mounting segment and the tapping segment. The reinforcing element is mounted on the tapping element between the elastic element and the tapping segment of the tapping element and abuts against the protrusion segment. The force-limiting and damping device can improve structural strength, can prolong service life, and can avoid deflection during a tapping process.