A crazed commuter punched an MTA conductor so hard that he hit his head on the wall of a subway train — during a brutal attack in Queens early Thursday, cops and sources said. 

The maniac slugged the 37-year-old transit worker in the face on board a Manhattan-bound A train passing through Beach 25th Street in Far Rockaway around 1:30 a.m., after exchanging words with him, according to authorities and sources.

The blow was so forceful that the conductor hit his head on the train cabin wall, police said. 

Far Rockaway-Mott Av A train stationThe maniac slugged the 37-year-old transit worker in the face on board a Manhattan-bound A train passing through Beach 25th Street, cops and sources said. Google

He was taken to St. John’s Episcopal Hospital, where he was listed in stable condition. 

The male attacker, last seen wearing a black coat, ran off after the attack and remained on the loose, police said. 

The maniac exchanged words with the 37-year-old transit worker on board a Manhattan-bound A train passing through Beach 25th Street in Far Rockaway around 1:30 a.m. before slugging him in the face, according to authorities and sources.The forceful punch caused the worker to hit his head on the train cabin wall, police said. Robert Miller

“Transit employees simply doing their jobs should never be subject to such outrageous and unacceptable attacks,” NYC Transit President Demetrius Crichlow said in a statement. 

“With our vast camera network, we are confident our law enforcement partners will find the person responsible who then must face justice for their reprehensible actions.”