Huddersfield defender John McCombe and midfielders Matthew Young and Aaron Hardy have all agreed one-year deals.
Centre-back McCombe, 21, has the most first-team experience with 11 appearances, including three starts.

Boss Peter Jackson told the Examiner: "They have to learn and work hard and, if they do that, then they'll have every chance of pushing for the team.

"I've told them if a first-team chance doesn't present itself then we'll consider sending them out on loan."