FIELD: medicine.SUBSTANCE: invention refers to medical equipment, namely to a component assembly for a drug delivery device, as well as to a drug delivery device which can be used for the unassisted drug delivery by the patient from the device. The component assembly for the drug delivery device comprises a body, a dosing chain, a trapping chain and a stopper chain. The body has a proximal end and a distal end. The dosing chain is movable in the proximal direction in relation to the body to set a drug dose. The trapping chain is movable in the proximal direction in relation to the body when setting the dose. The stopper chain is configured to locate a trip limit of the trapping chain for the proximal dislocation of the trapping chain in relation to the body. The trapping chain being in the position of the stroke limitation of the trapping chain is prevented from the additional motion in the proximal direction in relation to the body. The trapping chain and the dosing chain are configured for mechanical interaction to each other, when the trapping chain is found in the position of stroke limitation thereby preventing from the additional motion of the dosing chain in the proximal direction in relation to the body when setting the dose. The drug delivery device comprises the above component assembly, as well as a cartridge containing the drug. The component assembly represents a component assembly with an end limiter configured to prevent setting the drug amount exceeding the drug amount currently in the cartridge to be delivered. The cartridge has a proximal end and a distal end, a piston retained in the cartridge. The piston is movable distally in relation to the cartridge for drug dose delivery from the cartridge. The stopper chain position in relation to the distal end of the cartridge indicates the drug amount currently available in the cartridge.EFFECT: invention prevents setting the required drug dose exceeding the drug amount currently available in the cartridg
