The Day Out with Thomas included a full-size Thomas while his fellow engine Henry transported families in 1920s passenger carriages on 50-minute return rides to Buxton.
The Fat Controller was available for a hello and photos while volunteer staff provided intricate details about the train line that was once part of the Melbourne run until bypassed in the 1920s.
The lush grass area gave way to Thomas jumping castles, mini Thomas train rides and face painting with plenty of space left for visitors to enjoy the many picnic areas.
Donald, the black engine, remained parked but billowed along while knowledgeable staff explained the inner workings of steam technology.
Some of the rail lines lead into the museum which, along with the Great Train Hall and Roundhouse, were upgraded in the past few years.
The museum has elements of the train station scene from the first Harry Potter movie with the Governor-General's carriage, aptly nicknamed the "palace on wheels", on display.
Children delighted in entering the prison carriage which is equipped with mannequins and a motion-sensor that triggers an audio script between inmates.
At the far end of the museum is the old mail train equipped with a small slide that pops children out in front of the Legend of 1021 theatrette.
The lights go out before a curtain is rolled back, displaying steam engine Cardiff 1021 that arrived to NSW in 1916.
The audio and visual effects included moving and talking holograph images of the men who once worked on the small engine during two World Wars and the years following until its retirement in 1970.
Had enough?
Venture outside to the Great Train Hall where more than 60 locomotives and carriages span hundreds of metres in length and include the State Governor's car, the rail pay bus and the "rolling grocery store".
At the end of the hall is the working roundhouse where staff perform maintenance and upkeep.
On Thomas days, Toby the Rail Motor, ferries visitors back from the far end of the Hall to the museum if you're not up to the long return walk.
IF YOU GO
GETTING THERE: Trainworks is in Thirlmere, south of Sydney and northeast of Canberra.
STAYING THERE: Trainworks is an easy day trip from Sydney, but if you're looking for accommodation try the NSW South Coast near Wollongong. Check out visitnsw.com.
PLAYING THERE: Trainworks is open seven days a week but closed on Good Friday and Christmas Day, with more information on trainworks.com.au.
The next Days Out with Thomas are the weekends of July 13-14 and September 28-29.
• The writer was a guest of Trainworks
- AAP