Abstract: Several systems and methods for monitoring the proximity of a device to a power line are disclosed. Electric field monitoring systems are mounted to the device and include a plurality of electric field sensors and a monitoring system base unit. Each electric field monitoring sensor senses the strength of a magnetic field in which the sensor is positioned and transmits a corresponding magnitude output signal to the base unit when polled by the base unit. If a sensor reports a magnetic field exceeding a threshold, the frequency of polling for that sensor may be increased. If a sensor reports a magnetic field exceeding another (possibly identical) threshold, an alarm may be activated, movement of the device may be limited or stopped or another action or a combination of actions may be taken.

Abstract: Several systems and methods for monitoring the proximity of a device to a power line are disclosed. Electric field monitoring systems are mounted to the device and include a plurality of electric field sensors and a monitoring system base unit. Each electric field monitoring sensor senses the strength of a magnetic field in which the sensor is positioned and transmits a corresponding magnitude output signal to the base unit when polled by the base unit. If a sensor reports a magnetic field exceeding a threshold, the frequency of polling for that sensor may be increased. If a sensor reports a magnetic field exceeding another (possibly identical) threshold, an alarm may be activated, movement of the device may be limited or stopped or another action or a combination of actions may be taken.

Abstract: A clutch arm centering device is disclosed. The device is mounted on a clutch using to operate piston valves on a crane or other heavy machine. The piston valves may be operated using a valve arm which has two operative positions and a neutral position between the two operative positions. A clutch arm of the clutch is linked to valve arm to allow the valve arm to be manipulated by a remote control coupled to the clutch. As parts of the linkage between the clutch arm and the valve arm wear, the centering device biases the clutch arm to a central position which corresponds to the neutral position of the valve arm, thereby avoiding problems of understroking and overstroking which arise in the prior art.