English to Italian Law/Patents Engineering (general) fastener magazine

Ho una figura in cui l'elemento in questione è rappresentato come un elemento a soffietto. Come ad esempio un elemento cedevole che permette che si riduca la distanza tra una punta di un dispositivo e una specie di stantuffo.

Personalmente avevo in mente due opzioni che però non mi convincono molto:
1) raccordo di accoppiamento
2) elemento cedente

ecco alcuni esempi
A spring-loaded or otherwise biased follower urges the fasteners toward the nosepiece.

A follower rail is secured and extends between the nosepiece and the rear bracket, and sup-ports a magazine follower which is biased toward the nosepiece by a return or negator spring. The follower is depicted in two positions, a fully extended position (shown in broken lines) where it is close to the nosepiece, and a fully retracted position where it is closest to the rear bracket and is lockable for fastener loading. It will be understood that when the follower is extended, or closest to the nosepiece, the spring is retracted, and when the follower is fully retracted, the spring is fully extended.

As each slot is emptied of fasteners, the user pulls back the follower toward the rear bracket. As the follower approaches the grooved cam, the locating lug engages the uppermost groove as described below.