door stop, door jam, touch
棖 centers on a physical barrier or point of contact: a door stop or door jam that blocks movement, and by extension the act of touching or coming against something.
棖 combines 木 (tree/wood) with 長, which likely contributes the sound. The exact historical development is uncertain, but the structure suggests a wooden object related to the meaning of 長 (long) or used as a phonetic.
A wooden (木) post that is long (長) and used to stop a door: a door stop. When the door touches it, it makes contact.
For トウ, imagine a tall wooden door stop shaped like a tower: tower -> トウ, and it stops the door with a touch.