lift up, hold up, support
擎 centers on physically raising or sustaining something with effort: lifting up, holding up, or supporting a weight.
擎 combines 敬 (respect, but here likely a phonetic component) with 手 (hand) to express the action of lifting or holding up with the hands. The exact historical development is uncertain, but the phono-semantic structure is plausible.
The top part 敬 looks like a person carrying something respectfully, and the bottom 手 is a hand. Imagine hands lifting up a heavy object with care and effort.
For ケイ, picture a strong person lifting a heavy KEG (ケイ) with both hands: the keg is heavy, so they must hold it up with effort.