Surgical instrument motor pack latch

A robotic surgical assembly comprising:

• an end effector including an articulated feature;
• an elongate instrument shaft having a distal end supporting the end effector and a proximal end;
• a chassis supporting the instrument shaft proximal end, the chassis being detachably mountable to a robotic arm;
• the chassis including an actuation input drivingly coupled with the end effector articulated feature;
• a motor pack detachably mountable to the chassis, the motor pack including an actuation output that drivingly couples with the chassis actuation input when the motor pack is mounted to the chassis, the motor pack and the chassis having complementary-shaped interfaces providing sliding engagement between the motor pack and the chassis along an engagement axis;
• and
• a latch mechanism configured to selectively retain the motor pack to the chassis, the latch mechanism including a latch shaft, a torsion spring;
• and a transverse latch member;
• the latch shaft being mounted to one of the motor pack or the chassis to rotate about a latch shaft axis;
• the torsion spring being operably coupled with the latch shaft to bias the latch shaft into a pre-engagement orientation relative to the one of the motor pack or the chassis when the motor pack is not mounted to the chassis, the transverse latch member being mounted to the other one of the motor pack or the chassis and oriented transverse to the latch shaft axis when the motor pack is slidingly engaged with the chassis along the engagement axis, the transverse latch member interfacing with the latch shaft to rotate the latch shaft about the latch shaft axis in a first rotational direction in response to relative movement of the motor pack toward the chassis along the engagement axis from a pre-engagement configuration to an intermediate configuration, the latch shaft being configured to rotate opposite to the first rotational direction in response to relative movement of the motor pack toward the chassis along the engagement axis from the intermediate configuration to a retention configuration, the latch shaft blocking movement of the transverse latch member in the retention configuration to restrain the motor pack from moving away from the chassis along the engagement axis.