The present invention relates to a drive mechanism for use with a medicament delivery device, comprising a plunger rod (68), a drive spring (72) operably arranged to the plunger rod, an actuator (52) comprising a holding member (60) releasibly engaged to the plunger rod (68) for holding said plunger rod (68) with said drive spring (72) in a tensioned state, a rotator (38) operably connected and movable relative to said actuator (52) and configured to interact with said holding member for holding said holding member in engagement with the plunger rod, an activator (30) operably connected to said rotator (38). The invention is characterized in that the activator (30) is configured to rotate and subsequently linearly displace the rotator (38) in relation to the actuator (52) such that said holding member (60) is released from the plunger rod (68).本發明有關用於與藥物輸送裝置一起使用的驅動機構，包含柱塞桿(68)；驅動彈簧(72)，可操作地配置至該柱塞桿；致動器(52)，包含可釋放地嚙合至該柱塞桿(68)之固持構件(60)，用於以在拉緊狀態中的驅動彈簧(72)固持該柱塞桿(68)；轉子(38)，可操作地連接及可相對該致動器(52)運動，且被建構來與該固持構件互相作用，用於與該柱塞桿嚙合地固持該固持構件；啟動器(30)，可操作地連接至該轉子(38)。本發明的特徵為該啟動器(30)被建構來旋轉及隨後關於該致動器(52)線性地位移該轉子(38)，使得該固持構件(60)係由該柱塞桿(68)釋放。
