Although relatively in its infancy, electrocoating, sometimes termed anodic-hydrocoating, is a process of applying organic finishes through the use of electrical energy. In carrying out the basic process, an article to be coated is immersed in an electrolyte, defined as a specially formulated, water-soluble paint, where electrical current is then passed through the article and the electrolyte for a given period of time. Upon application of electrical energy, the resin and pigment forming part of the aforesaid electrolyte migrate to the article and a film is irreversibly deposited thereon. Thereafter, and in a typical procedure, the article may be rinsed, dried and baked, either directly, or after being overcoated wet on wet with a conventional compatible paint.
In continuous type electrocoating processes, the parts to be coated are typically individually suspended from associated overhead trolleys which track on an I-beam monorail conveyor, such as illustrated in the Koch et al U.S. Pat. No. 3,640,814. One problem encountered with such conveyorized systems has been the provision of an adequate bus bar grounding contact structure capable of maintaining the trolley arms at electrical ground potential so that arcing or sparking does not occur through the ball bearings of the trolley wheels which, in turn, make electrical contact with the overhead monorail beam which is preferably employed as the main ground bus bar leading to the main ground terminal of the power supply of the electrocoating system. Attempts to solve this problem are illustrated, for example, in the prior art Boost et al U.S. Pat. No. 3,669,870 and Koch et al U.S. Pat. No. 3,607,711. However, these prior art efforts to solve the grounding problem involved considerable additional leaf-spring brushes and associated mounting super-structure. Moreover, by utilizing wiper spring commutation with the drive chain of the conveyor, these prior systems posed additional problems of brush and chain wear and intermittent electrical contact, as well as interference from the chain lubricants, resulting in less than optimum system performance as well as relatively high cost in terms of materials, fabrication, installation and maintenance.