A chain saw includes a chain, a guide plate, and a locking device for tensioning the chain. The locking device includes an operating member rotatable about a first axis, a driving member for driving the guide plate to move to tension the chain, a first clutch coupling with the operating member, and a second clutch including meshing teeth cooperating with the first clutch. The driving member is connected with the second clutch, each of the meshing teeth includes a first sloped surface having a first slop and a second sloped surface having a second slop, the absolute value of the first slope is greater than that of the second slope.

A handheld battery-powered chainsaw comprises an electric motor (22) and a transmission arrangement (28) coupled to the electric motor (22), wherein the electric motor (22) is configured to drive a saw chain via the transmission arrangement (28). The transmission arrangement (28) comprises a slip clutch (34), comprising a drive member (36) configured to receive rotary power from the electric motor (22) and a driven member (38) configured to transmit rotary power to the saw chain (16), wherein the slip clutch (34) is configured to at least partly disengage the electric motor (22) from the saw chain by enabling a slip in the engagement between the drive member (36) and the driven member (38).

A handheld battery-powered chainsaw comprises an electric motor (22) and a transmission arrangement (28) coupled to the electric motor (22), wherein the electric motor (22) is configured to drive a saw chain via the transmission arrangement (28). The transmission arrangement (28) comprises a slip clutch (34), comprising a drive member (36) configured to receive rotary power from the electric motor (22) and a driven member (38) configured to transmit rotary power to the saw chain (16), wherein the slip clutch (34) is configured to at least partly disengage the electric motor (22) from the saw chain by enabling a slip in the engagement between the drive member (36) and the driven member (38).

In a hand-held power tool with a drive motor and a clutch connected to the drive motor and having an output part, the drive pinion is fixedly connected to the output part of the clutch so as to be driven by the drive motor for driving a tool. The drive pinion has a first individual part and a second individual part that are fixedly connected to each other. The first individual part has a toothing and the second individual part is connected to the output part of the clutch.

In a hand-held power tool with a drive motor and a clutch connected to the drive motor and having an output part, the drive pinion is fixedly connected to the output part of the clutch so as to be driven by the drive motor for driving a tool. The drive pinion has a first individual part and a second individual part that are fixedly connected to each other. The first individual part has a toothing and the second individual part is connected to the output part of the clutch.

Multi-speed automatic transmissions for power tools are provided. A multi-speed automatic transmission includes an output shaft configured to be coupled to a chain sprocket to rotatably drive the chain sprocket, wherein the automatic transmission is configured to automatically shift between a plurality of gear ratios in response to a rotational speed of the output shaft reaching a preset rotational speed.

Multi-speed automatic transmissions for power tools are provided. A multi-speed automatic transmission includes an output shaft configured to be coupled to a chain sprocket to rotatably drive the chain sprocket, wherein the automatic transmission is configured to automatically shift between a plurality of gear ratios in response to a rotational speed of the output shaft reaching a preset rotational speed.

A working machine may include a prime mover including an output shaft, a working part coupled to the output shaft, a slip mechanism, and a fan attached to the output shaft via the slip mechanism. The slip mechanism may be configured to: in a case where a load torque applied on the output shaft when driving the fan is less than a predetermined value, rotate the output shaft and the fan integrally with each other, and in a case where the load torque when driving the fan is greater than or equal to the predetermined value, rotate the output shaft and the fan relative to each other.

A working machine may include a prime mover including an output shaft, a working part coupled to the output shaft, a slip mechanism, and a fan attached to the output shaft via the slip mechanism. The slip mechanism may be configured to: in a case where a load torque applied on the output shaft when driving the fan is less than a predetermined value, rotate the output shaft and the fan integrally with each other, and in a case where the load torque when driving the fan is greater than or equal to the predetermined value, rotate the output shaft and the fan relative to each other.

A chain bar unit for a wall saw is presented herein. The chain bar unit can include a bar configured to receive a circulating chain or wire around a perimeter of the bar. The chain bar unit also can include a driving gear for driving the chain or wire around the bar, the driving gear configured to be coupled to an output shaft of the wall saw. The chain bar unit further includes the bar being tapered from an end proximate to the driving gear to a distal end having a distal end radius, wherein a width of the bar at the proximate end, is at least two times the distal end radius of the distal end.