keep one's shoulder to the wheel

VERB
32 LETTERS · STARTS WITH K

keep one's shoulder to the wheel is a valid 32-letter word worth 45 points in Scrabble and 47 points in Words with Friends.

SCRABBLE WORDS WITH FRIENDS
K5E1E1P3O1N1E1'0S1S1H4O1U1L1D2E1R1T1O1T1H4E1W4H4E1E1L1
5 + 1 + 1 + 3 + 0 + 1 + 1 + 1 + 0 + 1 + 0 + 1 + 4 + 1 + 1 + 1 + 2 + 1 + 1 + 0 + 1 + 1 + 0 + 1 + 4 + 1 + 0 + 4 + 4 + 1 + 1 + 1 =45 PTS
DOUBLE WORD → 90TRIPLE WORD → 135
MEANING

What does keep one's shoulder to the wheel mean?

VERB · 1 SENSE
1

Work doggedly or persistently.

BROADER