This invention relates to shaft mounted eddy current drives or clutches and more particularly to the general type of drive in which a magnetic body is rotatably mounted on a driven shaft mounted hub. The body contains or supports an electric coil fed through slip rings from a relatively stationary brush holder assembly. A magnetic speed pick-up may also be employed by means of which the rotational speed of the output may be monitored.
In drives of the general kind described, it has been customary to provide a stationary mounting bracket or mounting member adjacent the drive for supporting the slip ring brush holder assembly and, when used, for supporting the speed sensing device, such as a magnetic pick-up. Since the clutches or variable speed drives of the kind to which the invention is applied are frequently mounted directly on a drive shaft of a prime mover, such as the shaft of an electric motor, it has been difficult in practice to maintain uniform spacing between the non-rotating portions, including the brush holder assembly and the magnetic pick-up on the one hand, and the slip rings and a toothed speed indicator gear on the other hand. Radial and/or axial misalignments between the driven member and the fixed electrical support brackets result in misalignments of the brush holder and/or the magnetic pick-up with respect to their cooperating rotating members, and result in operational difficulties. This is particularly true where the driven member includes or incorporates a drive pulley by means of which the power is taken from the driven member through V-belts or the like. Under the stress of load and load changes, the precise alignment and spacing between a fixed or non-rotating brush holder or magnetic pick-up or the like and the cooperating rotating elements is difficult to maintain.
USPTO Backgrounds
USPTO Backgrounds