B-Line Eaton series strut fittings and accessories, 3.93" Height, 3" Length, 1.625" Width, .68lbs, Steel, Four bearing light trolley assembly, 12 gaug

The B478ZN four bearing light trolley assembly carries a 100 lb design load. That is the figure to size against when you are hanging a light fixture, a festoon run, or a small movable load off a strut track. It is built from 12 gauge steel to ASTM A1011 with a 33,000 PSI minimum yield, so the load rating comes from the steel section, not just the bearings.

The B478ZN is steel with an electro-plated zinc finish. That is a standard indoor, dry-location coating, fine for warehouses, plant ceilings, and covered areas. For sustained outdoor exposure, wash-down bays, or corrosive process areas, specify a hot-dip galvanized or stainless trolley instead, since electroplated zinc is a thin sacrificial layer.

B478ZN is a complete four bearing light trolley assembly, ordered as a single piece, so the four bearings and the body arrive together. What it does not include is the strut channel it rides in, the end stops, or the hanger hardware that ties your fixture to the trolley. Those are ordered separately to suit the run.

A fixed strut clamp holds a fixture in one spot. The four bearing trolley rolls along the channel, so use it where a light or a cable drop has to move along the run, such as a service bay, a maintenance pit, or a festoon feed following equipment. The four bearings spread the load and keep the body from cocking in the channel under its 100 lb design load. If nothing needs to travel, a fixed strut fitting is cheaper and simpler.