In a substrate polishing apparatus where a polishing liquid passes through inside a rotary joint, the rotary joint requires maintenance. There is provided a substrate polishing apparatus that includes: a polishing head for holding a substrate; a rotary table that has a surface to which a first opening portion is provided; a polishing liquid discharge mechanism disposed to the rotary table; and a controller configured to control at least the polishing liquid discharge mechanism. The polishing liquid discharge mechanism includes a first cylinder, a first piston, and a driving mechanism that drives the first piston. The first opening portion is communicated with a liquid holding space defined by the first cylinder and the first piston. The controller controls the driving of the first piston by the driving mechanism to increase and decrease a volume of the liquid holding space.

A grinder including a motor, a switch operated ON and OFF in accordance with an operation of a switch lever to control a rotation of an output shaft of the motor, a spindle that rotates in accordance with the rotation of the output shaft to rotate a disk-shaped grinding wheel and a brake mechanism controllable with respect to a brake plate that integrally rotates with the output shaft, in a housing, the brake plate includes fins.

A grinder including a motor, a switch operated ON and OFF in accordance with an operation of a switch lever to control a rotation of an output shaft of the motor, a spindle that rotates in accordance with the rotation of the output shaft to rotate a disk-shaped grinding wheel and a brake mechanism controllable with respect to a brake plate that integrally rotates with the output shaft, in a housing, the brake plate includes fins.

A grinder including a motor, a switch operated ON and OFF in accordance with an operation of a switch lever to control a rotation of an output shaft of the motor, a spindle that rotates in accordance with the rotation of the output shaft to rotate a disk-shaped grinding wheel and a brake mechanism controllable with respect to a brake plate that integrally rotates with the output shaft, in a housing, the brake plate includes fins.

A grinder including a motor, a switch operated ON and OFF in accordance with an operation of a switch lever to control a rotation of an output shaft of the motor, a spindle that rotates in accordance with the rotation of the output shaft to rotate a disk-shaped grinding wheel and a brake mechanism controllable with respect to a brake plate that integrally rotates with the output shaft, in a housing, the brake plate includes fins.

A handheld work apparatus has a tool and a brake assembly for the tool. The brake assembly has an actuating element which acts on a brake element of the brake assembly. The actuating element is movable between a fixed position wherein the tool is not braked, and a released position, wherein the brake element brakes the tool. To fix the actuating element in the fixed position, an electromagnet is provided. The electromagnet interacts with an anchor on the actuating element. The anchor is mounted via a pivot joint on an anchor pin to be pivotable about a pivot axis. A guide includes a guide part connected to the anchor and a guide part connected to the yoke, wherein, in the fixed position of the actuating element, the guide parts guide the anchor relative to the yoke in a transverse direction of an outrigger of the apparatus.

A handheld work apparatus has a tool and a brake assembly for the tool. The brake assembly has an actuating element which acts on a brake element of the brake assembly. The actuating element is movable between a fixed position wherein the tool is not braked, and a released position, wherein the brake element brakes the tool. To fix the actuating element in the fixed position, an electromagnet is provided. The electromagnet interacts with an anchor on the actuating element. The anchor is mounted via a pivot joint on an anchor pin to be pivotable about a pivot axis. A guide includes a guide part connected to the anchor and a guide part connected to the yoke, wherein, in the fixed position of the actuating element, the guide parts guide the anchor relative to the yoke in a transverse direction of an outrigger of the apparatus.

A power tool which brakes a motor without turning off a trigger switch when a trouble occurs in the motor is provided. The power tool (10) comprises: a motor (20) that rotates by supply of electricity from a power source (PS); a controller (38) for controlling the rotation of the motor; a switch (12) for switching on and off of power supply from the power source to the motor manually; first braking means (23) for braking the motor when the switch (12) is switched from on to off; and second braking means (23, 45) for braking the motor (20) on the basis of a prescribed signal from the controller when the switch (12) is in an on state.

A grinder includes a brake mechanism, a switch lever, and a slide bar. In the grinder, an interlocking mechanism configured to interlock the brake mechanism with the switch lever includes a link member that is interposed between the switch lever and the slide bar, that moves the slide bar to the forward position at the push-in position of the switch lever, and that moves the slide bar to the retraction position at the initial position of the switch lever.

A grinder includes a brake mechanism, a switch lever, and a slide bar. In the grinder, an interlocking mechanism configured to interlock the brake mechanism with the switch lever includes a link member that is interposed between the switch lever and the slide bar, that moves the slide bar to the forward position at the push-in position of the switch lever, and that moves the slide bar to the retraction position at the initial position of the switch lever.