Large manipulator having an articulated boom , which comprises two or more boom arms , wherein the boom arms are connected pivotably via articulated joints to the respectively adjacent boom arm by means of a drive in each case, wherein at least one of the drives is designed as a hydraulic rotary drive , with - a first rotary drive element formed as a shaft, - at least two annular pistons , which are connected in a torqueproof manner to the first rotary drive element and are axially movable on the first rotary drive element along a sliding path (a) between respectively two end positions by being acted upon by a hydraulic fluid, wherein each annular piston has two annular spur toothings directed away from each other, - a second rotary drive element with annular toothings complementary to the spur toothings of the annular pistons , wherein the spur toothings of the annular pistons can be brought into engagement and out of engagement with the associated annular toothings of the second rotary drive element by moving the annular pistons on the first rotary drive element , whereby a rotational movement of the second rotary drive element occurs relative to the first rotary drive element , and - a control unit , which controls the action of the hydraulic fluid upon the annular pistons , wherein the control unit is configured to cause a reciprocating movement of the annular pistons on the shaft according to an operating signal, wherein the second rotary drive element is formed as a cylinder housing, wherein the annular pistons are axially movable on the shaft between the respectively two end positions along the sliding path (a) by being acted upon by the hydraulic fluid, characterised by a sensor arrangement connected to the control unit to detect the positions of the annular pistons along the respective sliding path (a), wherein the control unit controls the velocity of the annular pistons as a function of the signals of the sensor arrangement . - a first rotary drive element formed as a shaft, - at least two annular pistons , which are connected in a torqueproof manner to the first rotary drive element and are axially movable on the first rotary drive element along a sliding path (a) between respectively two end positions by being acted upon by a hydraulic fluid, wherein each annular piston has two annular spur toothings directed away from each other, - a second rotary drive element with annular toothings complementary to the spur toothings of the annular pistons , wherein the spur toothings of the annular pistons can be brought into engagement and out of engagement with the associated annular toothings of the second rotary drive element by moving the annular pistons on the first rotary drive element , whereby a rotational movement of the second rotary drive element occurs relative to the first rotary drive element , and - a control unit , which controls the action of the hydraulic fluid upon the annular pistons , wherein the control unit is configured to cause a reciprocating movement of the annular pistons on the shaft according to an operating signal, wherein the second rotary drive element is formed as a cylinder housing, wherein the annular pistons are axially movable on the shaft between the respectively two end positions along the sliding path (a) by being acted upon by the hydraulic fluid, characterised by a sensor arrangement connected to the control unit to detect the positions of the annular pistons along the respective sliding path (a), wherein the control unit controls the velocity of the annular pistons as a function of the signals of the sensor arrangement . <EOS>