A320 Idg
 

A320 IDGs...Has anyone out there rolled up their sleeves and dissected one of these beasts? If so, can said person explain what lies within?
I'm guessing that it is some type of fluid coupling. FCOM warns that the disconnect push button should not be pressed for longer than 3 seconds. How does this work and why is it potentially damgaing?
Airbus is a little light on in details for some systems, so any elaboration would be appreciated.

I'll let someone else tackle the first question... I had a look at the details for the 747-400 IDG and got lost on the technical discription... something about spring-biased flyweights, hydraulic control pistons and wobbler plates. Basically, however, it sounds like it's using hydraulic forces to control the mechanical output speed.

Re your second question.... You will burn out the disconnect solenoid if you hold the switch in for too long. Basically the same for all IDGs. If it wasn't already completely stuffed, it now is (if you've kept your finger on the button).

Regards.
Q.

Qavion is correct:
variable speed input drives a hydraulic pump. This in turn drives a hydraulic motor which drives the generator. The intention is to produce a constant speed from the motor. The stroke of the pistons in the pump, is varied by the angle of a swash plate as they go round and round producing a constant output. Long stroke for low input speeds and vice versa.
Also present; governor, control piston (moves swash plate), oil lubrication, oil cooling jets, scavenge pump, fuel cooled oil cooler, filter, deaerator and of course the electrical generator itself rotating at 24000 rpm when online.
The IDG disconnect is a solenoid which drives a pin into a spiral track somewhere on the input shaft. A couple of turns and the gearing disengages itself.

Thank you both for the replies, makes much more sense now.
Regards, Gyro.