Left hand radical - the indexing radical in its 3-stroke side form. Marks 扳 as a manual action: pulling, prying, or wrenching something physical. Anchors it in the hand-action family with 拉 (pull), 推 (push), 拽 (drag), 抓 (grab).
Right side 反 supplies the sound - fǎn shifted to bān through a labial alternation. The 'reverse / flip' meaning also fits beautifully: 扳 means to pull something back the other way (扳回 turn back, 扳手 wrench, 扳倒 wrest down). Same phonetic appears in 板 (board), 版 (edition), 返 (return).
