A drive assembly (50, 100) for an introducer assembly (10) for the deployment of an implantable medical device (16) includes a sprung element (52) coupled to a yoke (56). The yoke (56) is coupled to a gripper element (58). The yoke (56) is coupled to a first handle unit (30) of the introducer (10). The sprung element (52) is coupled to a proximal handle unit (32). A brake element (66, 102) acts to prevent operation of the sprung element (52) when no manual force is being applied to retract a sheath (24) and the assembly (10). When manual retraction force is applied to the gripper element (58), the brake element (66, 102) releases the sprung element (52) so that the latter can apply a force assistance to assist in the retraction of the sheath (24) and thereby to assist in the deployment of a medical device.
