A power tool includes a housing, a motor received in the housing, an output driven by the motor, and a control system. The control system includes a rotational motion sensor configured to generate a rotational motion signal that corresponds to a rotational motion of the housing about an axis, a current sensor configured to generate a motor current signal that corresponds to an amount of current drawn by the motor, and a control circuit that is configured to receive the rotational motion signal and the motor current signal and to control operation of the motor. The control circuit is configured: (a) to determine, based on the current signal, whether a detected kickback condition is likely to be false; (b) to determine, based upon the rotational motion signal, whether an uncontrolled kickback condition has occurred; and (c) to initiate one or more protective operations upon determining that an uncontrolled kickback condition has occurred and is not likely to be false.

A safety power assist for a manual press is provided. In another aspect, a press includes a tool, a manual actuator, a switch and an automatically powered actuator. A further aspect of the present press employs a spring which must be compressed beyond a predetermined pinching force before a switch is activated, where switch activation causes an automatically powered actuator to advance a workpiece-contacting punch or tool.

A single-wire safety system architecture is provided that yields reliable safety device monitoring without the need for dual redundant signal channels. The safety system comprises a safety relay acting as a communications master device and one or more compatible safety devices connected in series with the safety relay via a single-wire communication circuit. The safety device farthest from the safety relay on the safety circuit modulates a safety signal with a recognizable pulse pattern that traverses the single-wire safety circuit to the safety relay via the intermediate safety devices. The safety relay maintains safety mode as long as the pulse pattern is received and recognized. The architecture allows bi-directional communication of initialization, configuration, and diagnostic messages over the single-wire safety channel, and can also allow safety devices to insert prognostic data into the safety signal in order to convey health information while the system is in normal operation mode.

A single-wire safety system architecture is provided that yields reliable safety device monitoring without the need for dual redundant signal channels. The safety system comprises a safety relay acting as a communications master device and one or more compatible safety devices connected in series with the safety relay via a single-wire communication circuit. The safety device farthest from the safety relay on the safety circuit modulates a safety signal with a recognizable pulse pattern that traverses the single-wire safety circuit to the safety relay via the intermediate safety devices. The safety relay maintains safety mode as long as the pulse pattern is received and recognized. The architecture allows bi-directional communication of initialization, configuration, and diagnostic messages over the single-wire safety channel, and can also allow safety devices to insert prognostic data into the safety signal in order to convey health information while the system is in normal operation mode.

An overload control device for use with a floor machine having an electric motor is disclosed. The overload control device can include a power input and a power output connectable to the electric motor. The device can include a load detector, a current sensor operative to sense a current value supplied to the motor via the power output, and a cutoff relay interconnecting the power input and the power output. The cutoff relay being operative to supply power from the power input to the power output when activated, and interrupt power when deactivated. A controller receives a load present indication from the load detector and activates the cutoff relay if a load is present. The controller receives a current value from the current sensor, determines if the current value is greater than a threshold value, and deactivates the cutoff relay when the current value is greater than the threshold value.

An overload control device for use with a floor machine having an electric motor is disclosed. The overload control device can include a power input and a power output connectable to the electric motor. The device can include a load detector, a current sensor operative to sense a current value supplied to the motor via the power output, and a cutoff relay interconnecting the power input and the power output. The cutoff relay being operative to supply power from the power input to the power output when activated, and interrupt power when deactivated. A controller receives a load present indication from the load detector and activates the cutoff relay if a load is present. The controller receives a current value from the current sensor, determines if the current value is greater than a threshold value, and deactivates the cutoff relay when the current value is greater than the threshold value.

Methods and apparatus provide safety systems for operating equipment having confined spaces which, during normal use, have conditions, such as extreme temperatures, pressures and/or caustic/toxic chemicals or other harmful gases which can be fatal to an otherwise healthy adult human. To protect humans inadvertently trapped in the confined space after the start of a normal operation cycle, the safety systems not only stop the equipment which is creating the harmful condition, such as a cutting off a supply of high pressure steam, but also remove the harmful condition or render it survivable. Versions also open access doors permitting escape and/or rescue of persons trapped in the confined space.

Methods and apparatus provide safety systems for operating equipment having confined spaces which, during normal use, have conditions, such as extreme temperatures, pressures and/or caustic/toxic chemicals or other harmful gases which can be fatal to an otherwise healthy adult human. To protect humans inadvertently trapped in the confined space after the start of a normal operation cycle, the safety systems not only stop the equipment which is creating the harmful condition, such as a cutting off a supply of high pressure steam, but also remove the harmful condition or render it survivable. Versions also open access doors permitting escape and/or rescue of persons trapped in the confined space.

A resistance welding pinch protection system for use with a resistance welder, comprising a sensor array adapted to be secured around the base of a positive electrode of the resistance welder, the sensor array including a plurality of proximity sensors positioned along a perimeter of the sensor array, the plurality of proximity sensors defining an electrode operation field around the positive electrode, an input/output interface to be operatively connected to the resistance welder, and at least one processor in communication with the plurality of proximity sensors and the input/output interface, wherein in use, during the lowering of the positive electrode, the at least one processor interrupts the control signal to the resistance welding controller in order to stop the welding sequence, raising the positive electrode in response to the detection of an obstacle within the electrode operation field.

The invention relates to an emergency stop device for a power tool comprising an electrical power contact for releasably connecting a power source to the power tool, and an emergency stop circuit connected to the electrical power contact and configured to disconnect the electrical contact from the electrical power source upon receipt of an emergency stop signal by the emergency stop circuit. The invention further relates to a power tool, a system comprising such a tool and a method of performing emergency stop of a power tool.