Green’s Dictionary of Slang

1. (US) to leave quickly [railway jargon highball, a signal directing the train to go at full speed].

1930		G. Milburn ‘Gila Monster Route’ in Hobo’s Hornbook 158: The con highballed, and the manifest freight / Pulled out on the stem behind the mail, / And she hit the ball on a sanded rail.
1933		J.T. Farrell Gas-House McGinty 196: Hit the ball I said [...] you dirty Dutchman, hit the ball!
1943		AS XIX 35: [note] These grand trains [...] hit the ball at 50 miles an hour.
1962		Ragen & Finston World’s Toughest Prison 803: hit the ball – [...] to travel swiftly.

2. (US) to work hard, to be diligent at a job [sporting imagery].

1926		N. Klein ‘Hobo Lingo’ in AS I:12 651: Hit the ball—forced to ‘hustle’ for a job.
1928		J. Callahan Man’s Grim Justice 270: I resorted to persuasion in an effort to make the departmental heads [...] ‘hit the ball.’.
1933		J.T. Farrell Gas-House McGinty 202: We hit the ball here in the daytime.
1939		W. Attaway Let Me Breathe Thunder (1940) 224: I was the only man she ever took up with that could really hit the ball.
1944		J.T. Farrell ‘A Teamster’s Payday’ in To Whom It May Concern 60: He had had to keep hitting the ball, with kids coming, expenses mounting.
1962		Ragen & Finston World’s Toughest Prison 803: hit the ball – To work hard; to travel swiftly.