Podracing is extremely dangerous, as is maintaining the speedy vehicles. In the hectic pace of a race, safety comes in second place to winning. As such, the cheap and expendable pit droids often bolt out onto the racetrack to repair still cycling superheated engines with no regard to their personal safety.
When not in use, pit droids fold up into a compact package. They spring to activation when needed. A tap on the nose signals the droid to collapse back into stowed mode and rest.
The junk dealer Watto had a wide variety of droids in various states of repair in his shop on Tatooine. This included compressed pit droids that could spring into unpredictable action at the slightest tap.
A gifted mechanic at a young age, Anakin tended to rely on his own skills in maintaining his Podracer while a slave on Tatooine, rather than trust the chores to the hyperkinetic pit droids.
While nosing round Watto's junk shop during a visit to Mos Espa, Jar Jar Binks accidentally activated a pit droid and had to scramble to keep the droid from running about.