Abstract: It is an object of the present invention to provide a technique to increase efficiency of the output torque of the blushless motor to drive a power tool. A representative power tool may comprise a tool bit, a brushless motor to drive the tool bit, a battery to operate the brushless motor and a control device. The control device may operate the brushless motor by means of the battery. The control device may include an advance angle controlling section to control an advance angle of the brushless motor. According to the present teachings, the advance angle of the brushless motor may be determined based upon indexes that reflect working condition of the tool bit when the brushless motor is under the operation. By reflecting the working condition of the tool bit to the determination of the advance angle of the brushless motor, the brushless motor can be operated with higher efficiency under the various working condition such as a hard joint operation and a soft joint operation.

Abstract: It is an object of the invention to provide work control system that can prevent an interference of the transmitting signals of the power tools in relation to the work progress. A representative work control system according to the present teachings may include a plurality of power tools and detecting device. Each of the power tools may transmit signals relating to the work progress. The detecting device may detect the work progress of each of the power tools by receiving and detecting the signals transmitted from the respective power tools. The signals relating to the work progress may be transmitted from each power tool several times. Preferably, the transmission intervals may vary among the power tools in order to prevent the signals from being confused.