This desk has a movable shelf.
The moving parts need regular lubrication.
固定 means fixed or stationary, the opposite of 可動 which means capable of moving.
可動 means 'movable' and describes parts designed to shift, directly opposing the physically fixed sense of 不動.
稼働 (same reading かどう) means the operation or running of machinery, whereas 可動 describes the mere capability of being moved.
range of motion; ROM
movable weir; adjustable dam gate
mobility
movable bridge
moving gadget on a pachinko machine
moving-coil type
Compound of 可 (possible) and 動 (move), literally 'able to move'. The reading is on'yomi.