Originally Posted by TenGrainBread

Those are Suntour XC Sport Roller Cam brakes. The design was by MTB pioneer Richard Cunningham. They used U-brake mounts but a very different mechanism.

The bike was not entry level. The lugged unicrown fork, black chrome, and Roller Cams were specced on High Sierras and Cimarrons in the mid-80s. So it was either Schwinn's top tier or 2nd from top tier MTB.