The invention relates to a hydraulic system, method, and integrated valve block for a slewing mechanism, comprising a first and second cylinder. The rod cavity of the first cylinder connects to the rodless cavity of the second cylinder through the first oil circuit, first hydraulic control check valve, and fourth oil circuit. The rodless cavity of the first cylinder connects to the rod cavity of the second cylinder through the second oil circuit, second hydraulic control check valve, and third oil circuit. The first oil circuit is connected to the directional valve through the sixth oil circuit, and the second oil circuit is connected to the directional valve through the fifth oil circuit. The directional valve is connected to the hydraulic pump and oil tank. The first hydraulic control check valve is installed between the first and fourth oil circuits, and the second hydraulic control check valve is between the second and third oil circuits. The check valves' control circuits connect to the sixth oil circuit, ensuring braking stability of the slewing mechanism.

A pneumatic stepper motor includes a housing, said housing accommodating at least part of: a rack or geared axle comprising a plurality of gear elements; and two pistons, each comprising at least two teeth, said pistons being arranged to cooperate with said rack or geared axle. The racks may either be straight or curved. The pistons are preferably double-acting pistons. A device includes at least one, and preferably a plurality of, such pneumatic stepper motor(s). The device may in particular be an MRI-compatible robotic system, more in particular for example an MRI-guided breast biopsy device.