If you wish to contribute or participate in the discussions about articles you are invited to join SKYbrary as a registered user
AP4ATCO - Hydraulic Systems/Answer 1
From SKYbrary Wiki
A hydraulic system consists of the hydraulic fluid plus three major mechanical components. Those components are the “pressure generator” or hydraulic pump, the hydraulically powered “motor” which powers the component concerned and the system “plumbing” which contains and channels the fluid throughout the aircraft as required.