A surgical instrument includes a body assembly, a waveguide, a transducer, and a coupling assembly. In some versions the coupling assembly translates the transducer to couple the transducer to the waveguide. For instance, a gear having arcuate troughs may engage pins on the transducer and/or waveguide to mate the transducer to waveguide. A pawl may selectively engage and prevent rotation of the gear. Alternatively, lever arms may cam the transducer into the waveguide. The lever arms may selectively couple to a casing to prevent decoupling of the transducer and waveguide. In another configuration, a locking tab can be slid and locked into a slot to couple the transducer and waveguide. Further still, levers with self-locking pins may engage and couple the transducer to the waveguide. In another version, a rotatable body portion may engage a tab on the transducer to rotate and couple the transducer to the waveguide.