I've never trusted the "throw-it-together-and-take-it-apart" rides that are available at temporary carnivals. In the past I've tried a few carnival rides and they've always seemed shoddy, some quite rickety, and they are clearly not as sturdy as permanent rides at established amusement parks. That's not to say that one can't get injured on a ride at large popular amusement parks like Cedar Point or Disneyland or Six Flags but at least the odds appear to be less, and those rides - which are under a higher surveillance and maintenance cycle - don't have multiple people constantly monkeying with them to move them from place to place. They have established 24/7 crews constantly observing, computerized monitoring, they will temporarily halt or close a ride down regardless of how long a line is to investigate every little odd noise or anything a rider reports as unusual, and they have on-site maintenance shops constantly replacing worn parts and doing quality assurance on a set schedule.