Testa della pompa a doppia valvola: come funziona? Cosa c'è dentro?

Descrizione:

In the video I disassemble a dual‑valve bike pump head to explain how it works, including why it doesn’t blow air out of the open hole. I also give a tip on extending the life of a leaking dual‑valve pump head, then reassemble it. The pump shown is a Park Tool PFP‑3. On this head the lever is pulled up to lock onto the valve stem; on other models the lever is raised when inserted and pushed down to lock.