The present invention concerns a mechanism (2) for a drug delivery device (1), having a longitudinal axis (21) and comprising a first member (17) comprising a first contact surface (27) and a second member (18) comprising a second contact surface (29), wherein the first member (17) is configured to be assembled to the second member (18), wherein the first member (17) and the second member (18) are configured such that the first contact surface (27) abuts the second contact surface (29) when the first member (17) is assembled to the second member (18), wherein the first contact surface (27) is arranged such that a force applied to the mechanism (2) in a direction parallel to the longitudinal axis (21) is split up into a first component (30) in a direction perpendicular to a surface normal (28) of the first contact surface (27) and a second component (31) parallel to the surface normal (28), wherein the first member (17) and the second member (18) are configured such that the first member (17) is detached from the second member (18) by the force applied to the mechanism (2) in a direction parallel to the longitudinal axis (21) if the absolute value of the force is stronger than a first predetermined value, and wherein the first predetermined value is defined as the absolute value of the force which has a first component (30) strong enough to move the first contact surface (27) out of abutment with the second member (18).
