Abstract: A metal oxide varistor module, and variations thereof for use in surge protectors and the like combining internally a thermally activated disconnect means and an excessive current disconnect means, such that when the module is subject to excessive overvoltage or overcurrent conditions, the connection is interrupted from the phase to neutral, phase to ground and any other combination of voltage or current before the metal oxide varistor device is physically damaged, ruptured or cracked.
Abstract: A foot pedal for varying resistance in an electrical circuit having an on-off control is formed having a base member with an actuator foot plate cover pivotally mounted thereto; an array of circular members is positioned in a circular recess between said base member and cover; said array including a pair of electrode discs spaced by a compressible resistance disc; said compressible resistance disc comprising a flexible elastomer with electro-conductive particulate dispersed therein; said array including an actuating plate which has a spherical joint connection with the actuator foot plate cover; an operator's foot pressure compresses the compressible disc to decrease resistance while a spring opens the pedal device when the operator's foot pressure is removed.
January 24, 1986
Date of Patent:
January 27, 1987
Thomas A. McMillan, Henry W. Mitchell, Alvin S. Cecil
Abstract: A power tool has an electric motor with a motor shaft having a spiral gear through which the motor drives the tool. A pressure sensor is disposed so as to be subjected to the axial thrust of the motor shaft created by the spiral gear during operation of the tool. A torque control device is connected to the pressure sensor for influencing the motor in response to such axial thrust, for example to control or limit the torque of the motor. Preferably, the pressure sensor comprises a disk of electrically conductive plastic and is located between a thrust bearing of the motor shaft and an axial support therefor. Such disk is disposed between a pressure plate and an electrode plate having spaced apart electrodes.
Abstract: A pressure sensitive conductor comprising an elastomer containing from 3 to 40% by volume of electrically conductive magnetic particles, which particles are dispersed in the elastomer so that high-sensitivity pressure sensitive conductor portions and insulator portions or low-sensitivity pressure sensitive conductor portions are both present therein. A method of manufacturing the pressure sensitive conductor comprises forming a sheet of a mixture containing electrically conductive magnetic particles in an elastomer, and subjecting the sheet to the action of magnetic fields before or during cross linking, thereby allowing the conductive magnetic particles to be uniformly dispersed in the sheet in a selected pattern.