keep one's nose to the grindstone vs keep one's shoulder to the wheel

keep one's nose to the grindstone and keep one's shoulder to the wheel both are verbs.

Word	Noun	Adjective	Verb	Adverb
keep one's nose to the grindstone	No	No	Yes	No
keep one's shoulder to the wheel	No	No	Yes	No

As verbs, keep one's nose to the grindstone and keep one's shoulder to the wheel are synonyms defined as:

keep one's nose to the grindstone and keep one's shoulder to the wheel: work doggedly or persistently

Other synonyms of keep one's nose to the grindstone include peg away, plug away, slog.

keep one's nose to the grindstone (verb)	keep one's shoulder to the wheel (verb)
work doggedly or persistently	work doggedly or persistently