heavy horse, horse unable to move because of twisted leg, plodding
驇 centers on a horse that is heavy, plodding, or unable to move freely, often due to a leg problem. The core idea is a horse burdened by its own weight or injury, moving slowly or not at all.
驇 combines 埶 (which may relate to planting or heavy growth) with 馬 (horse), suggesting a horse weighed down or stuck. The exact historical development is uncertain.
The top 埶 looks like a heavy, tangled mass pressing down on the horse 馬 below. Imagine a horse so burdened that it can only plod or becomes stuck.
For チ, picture a heavy horse trying to move but only managing a slow, plodding 'chi' sound with each labored step: chi -> チ.