Hello,
Based on the repair manual for the NLG, brakes on the 727 NLG were an option - the NLG can be built with them or without them.
Brakes on NLGs are rare: fighter aircraft for unprepare surfaces/icy surfaces being one of the few places you tend to see them (SAAB, MiG).
NLG brakes can be normal brakes used to shorten stopping distances (either to squeeze the aircraft into a shorter runway than normal - maybe the 727 case) or small brakes to stop the wheel rotation prior to retraction (this is usually done by straps in the NLG bay - a lighter and cheaper and more reliable option).