[′lim·əd·əd rō¦tā·shən hī¦drȯ·lik ′ak·chə‚wād·ər] (mechanical engineering) A type of hydraulic actuator that produces limited reciprocating rotary force and motion; used for lifting, lowering, opening, closing, indexing, and transferring movements; examples are the piston-rack actuator, single-vane actuator, and double-vane actuator.