A surgical robotic instrument comprising:a shaft；an end effector element；an articulation connecting the end effector element to the shaft, the articulation comprising:a first joint driveable by a first pair of driving elements, the first joint permitting the end effector element to rotate about a first axis transverse to a longitudinal axis of the shaft；a second joint driveable by a second pair of driving elements； a pulley arrangement around which the second pair of driving elements is constrained to move, the pulley arrangement comprising:a first set of pulleys rotatable about the first axis； anda second set of pulleys proximal to the first set of pulleys and comprising a first pulley rotatable about a second axis, and a second pulley rotatable about a third axis parallel to and offset from the second axis； anda clevis unit comprising two arms supporting the pulleys of the pulley arrangement, and a pulley guard extending from one of thearms for guarding one of the first and second pulleys.
