<prompt> tafadhali geuza maudhui haya ya swahili kwenda kwa kiingereza.kulingana na saizi na kiwango cha shinikizo ya mfumo, vibambo vya kudhibiti 2, 3 au zaidi vinaweza kuhitajika.  <response>: according to the needs of reversing and shunting, this kind of valve can have three or more channels. 