The Yoyodyne Division (also known as Yoyodyne Propulsion Systems or YPS) was a shipbuilding entity that built starships for the United Federation of Planets at various shipyards including 40 Eridani A Starfleet Construction Yards, Copernicus Ship Yards, and San Francisco Fleet Yards in the 24th century.
The Template:ShipClass starship Hathaway was built by Yoyodyne at Luna. (TNG: "Peak Performance")
The Template:ShipClass starship Brattain was built by Yoyodyne at 40 Eridani on stardate 22519.5. (TNG: "Night Terrors")
The Template:ShipClass starship Phoenix was built by Yoyodyne at 40 Eridani on stardate 40250.5. (TNG: "The Wounded")
The Nebula-class starship Sutherland was built by Yoyodyne in San Francisco on stardate 44820.5. (TNG: "Redemption II")
The firm had an office on Deep Space 9's Promenade.
The existence of this contractor is not from aired dialog, but is derived from the text of the starship dedication plaques. It is a reference to The Adventures of Buckaroo Banzai Across the Eighth Dimension!, which, in turn, took the name from Thomas Pynchon's novels V. and The Crying of Lot 49 (Star Trek: The Next Generation Companion)
YPS might also be responsible for the Yoyodyne pulse fusion engine, which would mean that the group already existed in the early 22nd century.