The story
From Buck, the surname of American inventor Steward T. Buck, president of Buck Equipment Corp. Buck filed a patent for a "portable hoisting tower" in 1950 (approved in 1953), and the device was produced under the trademark "Buck hoist tower" or "HoisTower" from at least 1952 to 1975, when the company was acquired by Bil-Jax.
Etymology from Wiktionary, CC BY-SA 4.0.