Onstage at Smoke in late January, the all-star septet the Cookers were surging into high gear. The catalyst: their drummer, Billy Hart, who stirred up rhythmic eddies and punched out stinging cymbal accents while fixing the saxophonist Azar Lawrence with an eager, heat-of-battle grin.

On “Just,” a new album by Hart’s own long-running quartet, out Friday, he reveals some of that intensity in a more understated guise, playing alongside vanguard musicians a quarter century or more younger — the saxophonist Mark Turner, the pianist Ethan Iverson and the bassist Ben Street — and pulling off what has become, across his six-decade-plus career, a trademark Billy Hart feat: sounding effortlessly and perpetually contemporary.

“He’s a continual, consummate student of the music,” Turner said of Hart, 84, in a phone interview. While Hart’s style draws on the many eras in which he has been active, he continued, “he hasn’t changed his language into something that is based in a period.”

The bassist Buster Williams has worked with Hart since the early ’60s, first meeting him on a gig with the vocalist Betty Carter and later aligning with him in many other contexts, including the Mwandishi band, Herbie Hancock’s trailblazing electric-jazz sextet of the early ’70s. “He’s got that fresh understanding of things,” Williams said in a phone interview. “His vision is always looking forward.”

Outside the jazz world, Hart is largely unknown. But within the genre — where peers and fans refer to him as Jabali, or “rock,” one of the Swahili monikers bestowed on the members of the Mwandishi band by their associate James Mtume — his esteem is near-universal, a status reflected in a 2022 National Endowment for the Arts Jazz Master designation and his staggeringly broad discography, encompassing more than 600 albums.