I believe it is a Zamperla Balloon Wheel.
Those things are driven by TEFC DC motors connected to a variable frequency inverter. If it was, as described in the story, a "compressor failure" then perhaps it was a problem of not being able to release the holding brake.
This brings up two questions, though...
a) If it was an air-released holding brake, could they have not connected an alternative air supply to get the wheel turning again? Fire trucks have air compressors on them, you know...
b) If it was a motor problem (a problem with a blower on a fan-cooled motor will keep the motor from running) then why could they have not manually pushed the wheel around? Unload the bottom tub, and push the wheel around...it will become increasingly unbalanced as it is unloaded until it will easily push itself around. I know that's how you unload a Rock-O-Plane or an Eli wheel without power...!
--Dave Althoff, Jr.
Who thinks fire departments have the wrong mindset about getting people off of high rides...it's always safer to bring the ride down first if possible...!