Chiron's Wheelchair is the magical wheelchair which Chiron uses to disguise himself as a regular mortal . Percy Jackson always wonders how he could get his back side into the wheelchair. He has come to the conclusion that the wheelchair was magic like the Hunters' back packs that are enchanted to hold numerous items.
Percy Jackson and the Olympians
The Lightning Thief
Chiron uses his wheelchair to hide his stallion body so he could be Percy's Latin teacher - Mr. Brunner at Yancy Academy. He stays in the wheelchair, while playing Pinochle with Mr. D, until he gives Percy a tour of the camp.
The Titan's Curse
Chiron was in his wheelchair when he first met Nico.
The Battle of the Labyrinth
Chiron was confined to his chair because he was injured during the battle.
The Last Olympian
Chiron is in his wheelchair form when he exits the van at the bottom of the Empire State Building when Percy calls them, so as not to alarm mortals.
Film
The Lightning Thief
In the film, Chiron is seen in the wheelchair during the first part of the movie, up until Grover and Percy leave the museum. The next time they see him, he is in full centaur form. The wheelchair is never seen without Chiron in it in the film, although before the Capture the Flag game, Luke said to him, "Chiron, you still got your wheelchair? Kid's gonna need it," referring to Percy who didn't yet have a helmet, although Luke was only joking.