A circular saw includes a support surface for a workpiece and which has a saw blade slot, a main drive motor arranged below the support surface for driving a saw blade in rotational movement, and a saw blade holder connected to the main drive motor for the purpose of transmitting the rotational movement A height-adjustment apparatus, with a height actuator and a transmission element coupled to the saw blade holder are arranged to set the spacing between a saw blade holder and the support surface An electronic interface provides the input of a saw blade projection. A protection apparatus is connected by signals to a monitoring apparatus and the height actuator and is adapted to activate the height actuator for quick lowering of the saw blade holder when a dangerous situation is recorded by the monitoring apparatus.

A blocking element for an emergency brake unit of a sawing device has a circular disc-shaped saw blade. The blocking element has a bearing portion, via which the blocking element is configured to be mounted on the sawing device, a head portion which is designed to engage into the saw blade selectively for braking purposes, and a deformation portion which is located between the bearing portion and the head portion and/or connects the bearing portion and the head portion to one another and which is arcuate and designed to be plastically shortened to brake the saw blade in an arc circumferential direction. A sawing device has a circular disc-shaped saw blade and an emergency brake unit. The emergency brake unit has such a blocking element which is mounted on the sawing device such that it can engage selectively into the saw blade to brake the saw blade.

A sawing device has a frame, a circular disc-shaped saw blade mounted rotatably with respect to the frame, and an emergency brake unit. The emergency brake unit has a blocking element, an actuator unit and a control unit. The blocking element has a bearing portion and a head portion designed to engage into the saw blade selectively for braking. The actuator unit is coupled to the blocking element in a normal blocking element position, such that the blocking element engages with the saw blade selectively with the actuator unit. The blocking element can be selectively disassembled from the frame separately from the actuator unit and/or from the control unit. A triggered emergency brake unit of a sawing device ready for operation may be provided. In this regard, a blocking element is disassembled separately from the actuator unit and/or separately from the control unit and an unused blocking element is mounted.

A system for protecting an operator (110) of a power tool (100) may include a first sensor network (240), a second sensor network (250), a third sensor network (252), and a controller (140) configured to detect a trigger event based on measurements made by the first, second and third sensor networks (240, 250 and 252) and initiate a protective action with respect to the power tool (100) responsive to detecting the trigger event. The controller (140) may be further configured to monitor performance data associated with each of the first, second and third sensor networks (240, 250 and 252) to perform sensor fusion based on the performance data.