The invention relates to a medicament delivery device comprising a locking mechanism (5) for locking a plunger rod (4). The locking mechanism (5) comprises a locking wheel (6) and locking means (7), said locking means (7) being moveable between an active position where the locking means (7) prevent the locking wheel (6) from rotation and an inactive position where the locking means (7) allow the locking wheel (6) to rotate, wherein said plunger rod (4) extends through an opening in the locking wheel (6) and a resilient member (8) arranged at the moveable locking means (7) and being arranged to act on the moveable locking means (7) to displace said movable looking means (7) towards the inactive position where the locking means (7) allow the locking wheel (6) to rotate.本發明有關藥物輸送裝置,包括用於鎖定柱塞桿(4)之鎖定機件(5)。該鎖定機件(5)包括鎖定輪(6)及鎖定機構(7),該鎖定機構(7)係可於該鎖定機構(7)防止該鎖定輪(6)旋轉之活動位置及該鎖定機構(7)允許該鎖定輪(6)旋轉的不活動位置之間運動,其中該柱塞桿(4)延伸穿過該鎖定輪(6)中之開口;及彈性構件(8),被配置在該可運動之鎖定機構(7)及被配置成作用於該可運動之鎖定機構(7)上,以位移該可運動之鎖定機構(7)朝該不活動位置,該鎖定機構(7)在此不活動位置允許該鎖定輪(6)旋轉。4‧‧‧柱塞桿6‧‧‧鎖定輪7‧‧‧鎖定機構8‧‧‧彈性構件12‧‧‧殼體14‧‧‧突出部份
