white horse
駱 centers on a white horse, specifically a horse with a white mane or a pure white horse. It is a specialized character for describing horse coat colors.
駱 combines 馬 (horse) with 各, which likely contributes the sound. The character was created to denote a white horse, with the horse radical specifying the meaning.
The left side is a horse 馬, and the right side 各 looks like a horse's flowing white mane. Picture a proud white horse with its mane blowing in the wind.
For ラク, imagine a white horse named Luck, galloping across a field: Luck -> ラク, and the white horse brings good fortune.