keep one's shoulder to the wheel vs plug away

keep one's shoulder to the wheel and plug away both are verbs.

Word	Noun	Adjective	Verb	Adverb
keep one's shoulder to the wheel	No	No	Yes	No
plug away	No	No	Yes	No

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

keep one's shoulder to the wheel and plug away: work doggedly or persistently

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

keep one's shoulder to the wheel (verb)	plug away (verb)
work doggedly or persistently	persist in working hard
	work doggedly or persistently