Abstract: The present disclosure relates to a device and a system for testing flatness. The device for testing flatness includes a base, a testing platform, and a ranging sensor. The testing platform is assembled on the base. The testing platform includes a supporting structure. The supporting structure is disposed on the side of the testing platform away from the base and is used to support a to-be-tested board. The structure matches the structure of the to-be-tested board. The ranging sensor is disposed on the side of the testing platform away from the base. After the to-be-tested board is placed on the testing platform, the ranging sensor is used to test distances between a number N of to-be-tested positions on the to-be-tested board and the ranging sensor, to obtain N pieces of distance information, and the N pieces of distance information are used to determine the flatness of the to-be-tested board, where N is an integer greater than 2.

Abstract: The present invention relates to a miter saw which includes a turntable, an elongate coupling mechanism pivotally mounted with respect to the turntable about a bevel axis to adjust to a bevel angle and a saw unit pivotally connected to the elongate coupling mechanism for movement between a non-cutting position and a cutting position. An angle enlarging mechanism is disposed between the turntable and the elongate coupling mechanism which is used for conveniently reading the bevel angle.

Abstract: A bench-top power tool having at least one movement-adjusting motor for driving movable part unit is described. The bench-top power tool comprises a base unit, a movable part unit, a primary motor and a movement-adjusting motor. The movable part unit connected to the base unit is capable of moving in relation to the base unit. The primary motor connected to the base unit is used to rotate a blade for cutting a workpiece. The movement-adjusting motor connected to the base unit and controlled with an open control mechanism drives the movable part unit to generate a relative motion in relation to the base unit.

Abstract: A switch for limiting and controlling a linear range of movement by rotational means. Two limiting positions of the switch are independently adjusted using worm gears. The switch includes a plate and a rotatable block having a rotatable shaft rotatably disposed relative to the plate. The plate has first and second electrolinking points spaced apart from each other. One end of a spring plate is fixed to the first electrolinking point, a middle portion of the spring plate is abutted against a circumferential edge of the rotatable block and the other end of the spring plate adopts two working positions with respect to the second electrolinking point.

Abstract: A trolley member for a garage door opener, comprises a trolley body (2), a connecting rod (7), a gear shaft (3) disposed on the trolley body (2), a rack (5) disposed on the trolley body (2), a gear (9) disposed on the gear shaft (3). The teeth of the gear (9) is engaged with the teeth of the rack (5). The rack (5) is connected to a spring device. The rack (5) has two working status. A first working status is that the rack (5) is inserted into a slot (10) of a chain link (8) and the spring member urges the rack (5) to the first working status, and a second working status is that the rack (5) is detached from the slot (10). The rack (5) is always urged to the first working status by the spring device, thereby the motor can reliably drive the chain and then the trolley member moving, and the chain can not be idling.

Abstract: The present invention relates to a switch for controlling the range of movement of (for example) a garage door.

Abstract: A trolley member for a garage door opener, comprises a trolley body (2), a connecting rod (7), a gear shaft (3) disposed on the trolley body (2), a rack (5) disposed on the trolley body (2), a gear (9) disposed on the gear shaft (3). The teeth of the gear (9) is engaged with the teeth of the rack (5). The rack (5) is connected to a spring device. The rack (5) has two working status. A first working status is that the rack (5) is inserted into a slot (10) of a chain link (8) and the spring member urges the rack (5) to the first working status, and a second working status is that the rack (5) is detached from the slot (10). The rack (5) is always urged to the first working status by the spring device, thereby the motor can reliably drives the chain and then the trolley member moving, and the chain can not be idling.