Zack is the head leader of the Chuggineers. He was first introduced in Season 4.
Zack joins Chuggington to head up the Chuggineers. This foreman is organised, hard-working and extremely safety consious, making him the perfect leader of the Chuggineer crew and mentor to Brewster. Joined by his fellow team members Tyne and Fletch, this engineering team are responsible for all the heavy lifting, loading and building of bridges, tunnels, stations as well as laying track and making repairs.
Zack is based on a GE Dash 9-44CWL diesel-electric hybrid engine.
- During production, he went through a couple different names: "Mack" and "Boyd". His basis was also, at one point, planned to be a EMD DDA40X.
- In German, he is called "Max".
- As seen in some promotional art and production photos, Zack was originally going to have bright blue eyes. They were changed to brown shortly afterwards.
- Zack is the only original member of the Chuggineers to still appear on the show.
- Season 4 - Rescue at Rocky Ridge, Wilson's Forest Flare, Stop Koko Stop!, Brewster Makes Tracks, Chief Wilson (mentioned), Back Up Brewster, Track Laying Brewster, Explorer Koko, The Old Silver Mine Line, Brewster Leads the Way, Winter Whiteout, Snow Patrol, Fearless Wilson, Blazin’ Wilson, On Track Brewster, We Are the Chuggineers, Team Trainee, The Tootington Tunnel, Iron Chuggers and Round Up Wilson (cameo)
- Season 5 - First Responder Calley (cameo), Sinkhole Rescue, Tour Guide Harrison, Delivery Challenge, Skipper Stu and the Steam Crane (dropped) Chug Patrol Chief and Fletch Shines
- Season 6 - Wilson's Broadcast Blues (mentioned), Not From Around Here, The Mighty Koko, The Fast, The Strong & The Wilson (cameo), Brewster's Greatest Gift (indirectly mentioned), Action Chugger's Day Off, Chugging Home for the Holidays and Celebrate Chuggington (cameo)
- Chugging Home and Brewster’s Song