Features for coupling surgical instrument shaft assembly with instrument body

An apparatus for operating on tissue, comprising:

• (a) a body assembly;
• (b) an ultrasonic transducer operable to convert electrical power into ultrasonic vibrations;
• (c) a shaft assembly configured to connect to the body assembly such that the shaft assembly extends distally from the body assembly, wherein the shaft assembly comprises a waveguide operable to transmit the ultrasonic vibrations;
• (d) a motor operable to rotate the ultrasonic transducer to thereby selectively couple the ultrasonic transducer with the waveguide;
• (e) a locking feature configured to selectively prevent rotation of at least a portion of the shaft assembly relative to the body assembly;
• and
• (f) a stress sensing feature configured to prevent the shaft assembly from being detached from the body assembly in response to sensing laterally oriented forces within the shaft assembly.

An apparatus for operating on tissue, comprising:

• (a) an ultrasonic transducer operable to convert electrical power into ultrasonic vibrations;
• (b) a shaft assembly having a waveguide operable to transmit the ultrasonic vibrations;
• (c) a body assembly configured to selectively connect to the shaft assembly such that the shaft assembly distally extends therefrom, wherein the body assembly comprises a sensor, wherein the sensor is configured to sense longitudinal positioning of the shaft assembly relative to the body assembly;
• and
• (d) a shaft lock, including:
• (i) a locking feature configured to selectively move from a first position to a second position to prevent rotation of at least a portion of the shaft assembly relative to the body assembly,
• (ii) a solenoid operatively connected to the locking feature and configured to selectively move the locking feature from the first position to the second position to thereby prevent rotation of the at least the portion of the shaft assembly relative to the body assembly.