دیکشنری تخصصی مهندسی نفت - نسخه آنلاین

n: in a kelly bushing, a double set of roller assemblies that are installed on two levels, or planes, within the bushing. Compare single-plane roller assembly. See also kelly bushing, roller assembly.

n: in a kelly bushing, a single set of roller assemblies that are installed in the bushing at the same level, or plane. Compare double-plane roller assembly. See also kelly bushing, roller assembly.