Tool with torque-actuated end effector

A system comprising:

• a tool (50) comprising:
• an instrument (100, 102) having a proximal end (20) and a distal (40) end comprising a shaft (130), the instrument (100, 102) provided with an end effector (300) at the distal end (40) actuated by torque,
• a drive shaft (402), at least partially flexible for transfer of torque from the proximal end (20) to the end effector (300), disposed in a lumen of the instrument (100),
• a rotor unit (400) comprising a body (410) disposed at the proximal end (20) of the instrument (100, 102) connected to the drive shaft (402), and that rotates around an axis of rotation (210) relative to the proximal end (20) of the instrument (100, 102),
• and
• a stator unit (500) configured to induce rotation of the body (410) around the axis of rotation (210),
• wherein
• the body (410) of the rotor unit (400) is configured for dismountable engagement with a stator unit (500),
• the body (410) of the rotor unit (400) is disposed with at least two cammed regions each configured to receive radial force from the stator unit (500) that induces rotation of the body (410) around the axis of rotation, and
• the stator unit (500) comprises a plurality of stator pushers (530-Ua, 530-Va, 530-Wa, 530-Ub, 530-Vb, 530-Wb, 530-Uc, 530-Vc, 530-Wc) configured for movement in a direction radial to a centre of rotation (405) of the body (410) of the rotor unit (400) and for the application of the radial force.