The fact that UEA slip ring assemblies are known for their dependable service in a wide variety of environments stems from their original design to operate in the rugged and dirty world of construction equipment. The first UEA slip rings were designed and built when UEA founder, Vern Iserman, was unable to locate or purchase a slip ring design that would stand up to the environments encountered by the electro-pneumatic remote control packages he was building and installing on small truck mounted cranes and draglines for the Shield Bantam Co. The patented brush assembly design included two brush contacts, each radiused to match the OD of the ring contact, with paralleling insulated brush shunt between the contacts. The contacts are each riveted to an insulating brush arm with the contact allowed to pivot around the rivet. The brush arms are stacked over a stainless steel stud, with the arms also allowed to pivot on the stud, and the two arms in each pair tied to each other with an extension spring. This design with three pivot points, including the brush contacts and the brush retention post, allows the UEA brush to maintain contact even with a considerable amount of misalignment or oscillation as the equipment and bearings wear. The brush design, with the spring insulated from the actual circuit, precludes the possibility of the spring losing tension due to overheating, etc. when the spring serves dual-duty as both the brush arm and conductor as used on many other slip ring brush designs. Operating with the high contact force of 15-18 lbs./sq. in. the UEA brush contacts not only provide very good cleaning action to wipe the rings as the brushes rotate but a very high resistance to contact bounce as the equipment vibrates. Another unanticipated advantage at the time of their design of the high contact pressure at the brush contact to ring interface is that the very low contact resistance permits the use of lower level signals such as video and audio even on some of the standard circuits with copper graphite contacts and brass rings.
Using variations of both contact and ring materials has allowed the basic double-contact UEA design from the 1960’s to be used in a wide variety of applications and environments around the world nearly 50 years later. Using that same basic brush design the UEA slip ring line has been expanded to meet through-bore slip ring needs from 0.50″ to 14.00″ in inside diameter.