A measuring device for measuring the wear of carbon brushes includes: a slip ring; a carbon brush, which is arranged for sliding in a sliding direction and which is preloaded into sliding contact with the slip ring; and an indicator material, which extends in the sliding direction in, on or next to the carbon brush and is connected to the carbon brush in such a way that the indicator material moves together with the carbon brush at least with respect to the sliding direction. The indicator material is preloaded into sliding contact with the slip ring. An insulator is arranged between the carbon brush and the indicator material and electrically insulates the carbon brush from the indicator material. A resistance-measuring apparatus measures the resistance between two measurement points, between which at least a section of the indicator material and a section of the slip ring lie, wherein the specific resistance of the indicator material is greater than the specific resistance of the carbon brush.

A measuring device for measuring the wear of carbon brushes includes: a slip ring; a carbon brush, which is arranged for sliding in a sliding direction and which is preloaded into sliding contact with the slip ring; and an indicator material, which extends in the sliding direction in, on or next to the carbon brush and is connected to the carbon brush in such a way that the indicator material moves together with the carbon brush at least with respect to the sliding direction. The indicator material is preloaded into sliding contact with the slip ring. An insulator is arranged between the carbon brush and the indicator material and electrically insulates the carbon brush from the indicator material. A resistance-measuring apparatus measures the resistance between two measurement points, between which at least a section of the indicator material and a section of the slip ring lie, wherein the specific resistance of the indicator material is greater than the specific resistance of the carbon brush.

The present invention is a sliding contact material having a composition of Cu of 6.0% by mass or more and 9.0% by mass or less, Ni of 0.1% by mass or more and 2.0% by mass or less, an additive element M of 0.1% by mass or more and 0.8% by mass or less, and the balance being Ag. The additive element M is at least one element selected from the group consisting of Sm, La and Zr. The present sliding contact material has a material structure in which dispersion particles containing an intermetallic compound containing at least both Ni and an additive element M are dispersed in an Ag alloy matrix. It is required that the ratio of a Ni content (% by mass) and a content of an additive element M (% by mass) (K.sub.Ni/K.sub.M) in the dispersion particles falls within a predetermined range. The present invention is an Ag alloy-based sliding contact material more excellent also in abrasion resistance than conventional ones, and a material adaptable to higher rotation numbers of micromotors.

The present invention is a sliding contact material having a composition of Cu of 6.0% by mass or more and 9.0% by mass or less, Ni of 0.1% by mass or more and 2.0% by mass or less, an additive element M of 0.1% by mass or more and 0.8% by mass or less, and the balance being Ag. The additive element M is at least one element selected from the group consisting of Sm, La and Zr. The present sliding contact material has a material structure in which dispersion particles containing an intermetallic compound containing at least both Ni and an additive element M are dispersed in an Ag alloy matrix. It is required that the ratio of a Ni content (% by mass) and a content of an additive element M (% by mass) (K.sub.Ni/K.sub.M) in the dispersion particles falls within a predetermined range. The present invention is an Ag alloy-based sliding contact material more excellent also in abrasion resistance than conventional ones, and a material adaptable to higher rotation numbers of micromotors.

The invention relates to a discharging device for discharging electrical interference, in particular currents, from a rotor part of a machine, said rotor part in particular being a shaft, into a stator part (17) of the machine, the discharging device having a contact device (11) comprising a contact element (13) which is accommodated in an axially displaceable manner in a guide and which is acted on by a contact force device (15) for generating a shaft contact force (F.sub.W) in order to establish electrical contact between a shaft contact surface (19) of the contact element (13) and a rotor contact surface (20) of the shaft (18), wherein the guide has a stator contact surface (25) for forming an electrical connection with the stator part (17) and the discharging device has a guide contact force device (21) for generating a guide contact force (F.sub.F) between a guide contact surface (24) of the contact element (13) and the stator contact surface (25) electrically connected to the stator part (17).

Systems and methods to mitigate electrical voltage on a rotating shaft in an oil rich environment exposed to a viscous fluid or immersed in oil are disclosed. An example grounding brush assembly includes a plurality of conductive filaments configured to extend through the viscous medium surrounding the rotating shaft to be in electrical contact with the rotating shaft when the brush assembly is disposed proximate the shaft.

In order to effect a seal a porous material which comprises one side of two opposing surfaces is used to restrict and evenly distribute externally pressurized gas, liquid, steam, etc. between the two surfaces, exerting a force which is opposite the forces from pressure differences or springs trying to close the two faces together and so may create a non-contact seal that is more stable and reliable than hydrodynamic seals currently in use. A non-contact bearing is also disclosed having opposing surfaces with relative motion and one surface issuing higher than ambient pressure through a porous restriction, wherein the porous restriction is part of a monolithic porous body, or a porous layer, attached to lands containing a labyrinth, the porous restriction and lands configured to not distort more than 10% of a gap created from differential pressure between each side of the porous restriction.

In order to effect a seal a porous material which comprises one side of two opposing surfaces is used to restrict and evenly distribute externally pressurized gas, liquid, steam, etc. between the two surfaces, exerting a force which is opposite the forces from pressure differences or springs trying to close the two faces together and so may create a non-contact seal that is more stable and reliable than hydrodynamic seals currently in use. A non-contact bearing is also disclosed having opposing surfaces with relative motion and one surface issuing higher than ambient pressure through a porous restriction, wherein the porous restriction is part of a monolithic porous body, or a porous layer, attached to lands containing a labyrinth, the porous restriction and lands configured to not distort more than 10% of a gap created from differential pressure between each side of the porous restriction.

Power tools with conductive couplings used with active injury mitigation technology are disclosed. Conductive couplings are particularly relevant to table saws, hand-held circular saws, track saws, miter saws, and band saws with active injury mitigation technology. Conductive couplings provide a mechanism through which an electrical signal can be coupled or imparted to a blade, and then monitored for changes indicative of human contact with the blade. An exemplary conductive coupling includes a brush that establishes an electrical connection with a moving part of a power tool, and the brush maintains contact with the moving part of the power tool during at least 40 hours of cumulative time when the motor is spinning the arbor and blade without an interruption in the electrical connection sufficient to trigger the reaction system. A conductive coupling may be two-sided compliant. A conductive coupling may connect to a motor shaft to minimize electrical noise.

A carbonaceous material is fabricated by a mixture of carbon powder and a binder. 10% by weight or more and 60% by weight or less of metal powder to the fabricated carbonaceous material is mixed. The mixed carbonaceous material and metal powder are pressurized and formed. A brush base material is fabricated by burning of the pressurized and formed carbonaceous material and metal powder. The fabricated brush base material is impregnated with oil. An impregnation rate of the oil to the mixed carbonaceous material and metal powder may be 0.5% by weight or more, for example.