Abstract: An impending kickback condition is the operation of a power tool or machine tool system is sensed and used to control or eliminate the kickback. The ability to sense an impending kickback condition can be used in all categories of power driven tools. The change in force applied to the power driven tool or other implement is monitored by measuring the rate of change of speed of the tool or implement, and if the speed is decreasing, the rate of change of speed is compared with a threshold value which may be either preset or variable. If this threshold value is exceeded, an output control signal is generated which inhibits the coupling of power to the tool or other implement and/or applies a brake to stop the tool or implement. In order for power to once again be coupled from the motive power source to the shaft, the start switch must be opened and then reclosed or some other signal provided by the operator or another predetermined condition must be met.

Abstract: An impending kickback condition in the operation of a power tool or machine tool system is sensed and used to control or eliminate the kickback. The ability to sense an impending kickback condition can be used in all categories of power driven tools. The change in force applied to the power driven tool or other implement is monitored with a microcomputer by measuring the rate of change of current. If the current is increasing, the microcomputer compares the rate of change of current with a threshold value which may be either preset or computed by the microcomputer. If this threshold value is exceeded, an output control signal is generated by the microcomputer which inhibits the coupling of power to the tool or other implement and/or applies a brake to stop the tool or implement. In order for power to once again be coupled to the tool or implement, the start switch must be opened and then reclosed or some other signal provided by the operator or another predetermined condition must be fulfilled.