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An electric variable speed drive includes a hub member, a driven member, a magnetic coupler, and a rotary electrical connector. The hub member is mounted for rotating with the shaft of a prime mover. The driven member is rotatably supported on the hub member by bearings, and includes a mechanical ou

An electric variable speed drive includes a hub member, a driven member, a magnetic coupler, and a rotary electrical connector. The hub member is mounted for rotating with the shaft of a prime mover. The driven member is rotatably supported on the hub member by bearings, and includes a mechanical output portion such as a pulley. The magnetic coupler includes an electric coil and magnetic poles which are mounted for rotating with one of the hub and the driven members. An armature is mounted to the other of the hub and driven members. An electric current is passed through the electric coil to magnetically couple the hub member to the driven member. The extent of the magnetic coupling between the hub and driven members is determined by the electric current passing through the electric coil. The rotary electrical connector includes a conductive fluid, such as liquid mercury, which extends between stationary and rotary contacts for passing the electric current from a stationary power source to the rotating electric coil. A fan and heater maintain the temperature of the rotary electrical connector between minimum and maximum operating temperature limits. Insulation prevents heat generated in operating the drive from raising the temperature of the rotary electrical connector.

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In an electric variable speed drive for magnetically coupling an input member to an output member for transferring mechanical power therebetween, the drive including bearing means for rotatably securing the input and output members for coaxially rotating around a common axis, an electric coil and ma

In an electric variable speed drive for magnetically coupling an input member to an output member for transferring mechanical power therebetween, the drive including bearing means for rotatably securing the input and output members for coaxially rotating around a common axis, an electric coil and magnetic pole means included with one of the input and output members, and an armature included with the other of the input and output members, wherein electric current passed through the electric coil determines the extent of magnetic coupling between the magnetic pole means and the armature to determine relative rotational speeds between the input and output members, the improvement comprising: rotary contact means mounted to the one of the input and output members which includes the electric coil for rotation therewith, the rotary contact means having an interiorly defined fluid chamber which extends around the common axis with a concave shape having a closed inner end and an open outer end which are spaced apart along the common axis; stationary contact means having a stationary contact coaxially disposed around the common axis and extending through the ope n outer end of the fluid chamber, the stationary contact being secured in fixed relation with and electrically connected to a stationary power source; sliding contact sealing means extending between the rotary contact means and the stationary contact means for sealing the open outer end of the fluid chamber; a rotary contact included within the rotary contact means and mounted to the one of the input and output members which includes the electric coil, to retain the rotary contact in a fixed spatial relation with and electrically connected to the electric coil, wherein the rotary contact is adapted for rotating about the common axis in a spaced apart relation to the stationary contact; and a conductive fluid disposed within the fluid chamber in direct fluid communication with both the stationary and rotary contacts, wherein the conductive fluid electrically connects between the stationary and rotary contacts to provide an electrical path for passing the electric current between the stationary power source and the electric coil.