Spindle for a drug delivery device

A dose setting mechanism for use with a drug delivery device comprising a housing, a clutch, a number sleeve, an inner housing, a spindle for driving a bung of a cartridge and further comprising a driver for driving said spindle, which extends about the spindle, with said driver comprising a helical groove form that engages a first helical groove of said spindle,

• said spindle comprising:
• a generally circular shaft having an outer surface, said generally circular shaft extending from a distal end to a proximal end of said circular shaft;
• a first helical groove provided along a first portion of said outer surface of said generally circular shaft, said first helical groove having a first pitch;
• and
• a second helical groove provided along a second portion of said outer surface of said generally circular shaft, said second helical groove overlapping said first helical groove, said second helical groove having a second pitch;
• wherein the number sleeve is in rotatable engagement with respect to said housing;
• wherein the driver is releasably coupled to said number sleeve with the clutch disposed about the driver between the driver and the number sleeve;
• and
• wherein the spindle is operatively coupled to said driver, such that when a user sets a dose by rotating said number sleeve, said driver also rotates,
• wherein the inner housing fits between the clutch and the number sleeve.