The present invention relates to a medicament delivery device comprising a housing, which housing is arranged to accommodate a medicament container； a drive unit arranged in said housing and capable of acting on a movable stopper positioned inside said medicament container for expelling a dose of medicament, wherein said drive unit comprises an elongated plunger rod and a dual back-to-back force spring assembly operatively connected to said plunger rod such as to provide a symmetrical load on said plunger rod； a locking and release mechanism operatively connected to said drive unit and capable of releasing said drive unit upon activation, wherein the locking and release mechanism comprises a hold member operatively connected to the plunger rod, a rotator member operatively connected to the hold member, and a tubular actuation member linearly slidable in relation to the housing and operatively connected to the rotator member； wherein the hold member is fixedly attached to the housing and comprises a general ly tubular lock tube through which the plunger rod extends and two seats designed as half-cylinders open towards the proximal direction for housing the dual back-to-back force spring assembly, and wherein the lock tube comprises resilient locking and release means configured to interact with both the plunger rod and the rotator member.本發明係關於一藥物輸送裝置包括一外殼用來容納一藥物容器；一驅動單元位於該外殼內且能夠作用於該藥物容器內的可移動栓塞上以排出一劑藥物，其中該驅動單元包括一瘦長柱塞桿和一雙背靠背力彈簧組可操作地連接於該柱塞桿以提供一對稱的負載於柱塞桿上；一鎖住和鬆開機制可操作地連接於該驅動單元且能夠藉由致動而鬆開該驅動單元，其中鎖住和鬆開機制包括一支撐構件可操作地連接於柱塞桿，一旋轉構件可操作地連接於支撐構件，和一管狀構件可相對於外殼線性滑動且可操作地連接於旋轉構件；其中支撐構件固定地附接於外殼且包括一普通管狀鎖套，柱塞桿延伸穿過其中，且兩座被設計為半圓柱，開口向著近端方向以收藏雙背靠背力彈簧組，且其中鎖管包括彈性鎖和鬆開裝置與柱塞桿和旋轉構件互動。
