A heavy-duty belt conveyor idler roll construction and a heavyduty seal assembly construction are disclosed. The idler roll is provided with a heavy gauge outer shell and flat end-head members that are welded to the shell at the inner diameter of the shell so that no weld splatter or rough edges are presented on the working surface of the shell. The idler roll is provided with a solid through-shaft surrounded by a grease sleeve which interconnects the bearing assemblies at the roll ends so that a one-point lubrication positively feeds the lubricants to and through the bearing assemblies and air pockets cannot form in the bearing cavities. Shaft supports are closely spaced to the bearing assemblies to reduce shaft deflection and increase bearing life. The seal assemblies include an outer oilimpregnated adjustable retaining member, a synthetic resin face seal member and a reinforced elastomeric lip seal member arranged to provide a five-pass labrinth seal for excluding foreign matter from the bearing assembly and locking lubricants within the bearing assembly and having characteristics of a dirt exclusion seal and a lubricant retaining seal.