Small rotating bodies in the form of balls, wheels, cylinders or truncated cones, used to assist movement by reducing friction.
Note 1: In lighthouse service, rollers are mainly used to assist and guide the movement of a rotating optic.
Note 2: In Germany, no general term equivalent to "rollers" exists, but particular terms are used when the rollers are in the form of balls (Kugellager), wheels (Walzenlager), cylinders (Zylinderlager) or truncated cones (Kegellager).
Please note that this is the term as it stands in the original IALA Dictionary edition (1970-1989)
International Association of Marine Aids to Navigation and Lighthouse Authorities - AISM