Delivery device

A drive mechanism contained in an outer shell of a delivery device, the drive mechanism comprising:

• a rotator comprising an outer surface and an inner surface, wherein the inner surface comprises a rotator rib;
• a needle cover slidably positioned and rotationally fixed within the outer shell, wherein the needle cover engages the outer surface of the rotator, and wherein the needle cover has a first, second, and third position relative to the outer shell, and wherein the needle cover is biased in a distal direction by a first spring;
• and
• a plunger rod comprising a distal end and a proximal end, wherein the plunger rod includes a plunger rod rib coupled directly to an outer surface of the plunger rod and projecting radially outward from the outer surface, wherein the plunger rod includes a retaining part,
• wherein a proximal movement of the needle cover relative to the outer shell enables the plunger rod to rotate from a first state to a second state via the plunger rod rib being engaged by the rotator rib as the plunger rod rotates together with the rotator from the first state to the second state, and then to translate axially to a third state, and
• wherein the proximal movement of the needle cover relative to the outer shell is configured to cause the plunger rod to rotate relative to the needle cover and the outer shell such that the plunger rod transitions to the second state where the retaining part is released and the plunger rod is no longer axially fixed relative to the outer shell.