The invention relates to a rotator (10) for jib-carried tools (1), for example tree working units, wherein the rotator (10) includes a stator (20) and a rotor (30), wherein the rotator (10) is connected to a tip (2) of the jib or arm (3) and to the tool (1). The rotator (10) has or includes in its surroundings means (70, 71) for determining the relative position of rotation between rotor (30) and stator (20). The means for determining the relative position of rotation comprises a pulse emitter (70) and a number of pulse generating elements (71), such as grooves or teeth. Limitation of the angle through which the rotator (10) can turn and control of the direction of rotation prevents, for instance, hoses and/or cables (7) from twisting or rotating away from their respective connections, while enhancing the extent to which automation can be achieved at the same time.