During a maintenance and bearing upgrade on one of my 7.5 KVA ST alternators I noticed that the fan was not running true; it was buckled. Whilst it was not a major issue I still decided to “correct” it. Having got the fan almost true I was ham-fisted enough to crack the fan casting. The crack is radial extending from the outside (where I was levering), propagating along the root of a fan blade, and terminating in the conical section behind the front bearing. The crack does NOT extend to the centre shaft.
Whilst I have used a 2 part epoxy adhesive to temporarily repair the crack (and it seems to work just fine), I intend to replace the fan.
The fan appears to be secured onto the rotor shaft by a combination of interference fit and keyway. There is a circlip in front of the fan (behind the front bearing) which I assume allows the fan to be pulled forward and removed. I also assume that the fan is impeded from moving further back towards the windings by a step in the shaft but this is not obvious. There appears to be a keyway of some kind in the shaft axially in line with the main shaft keyway but no obviously visible key.
So,….
1. Has anyone actually tried to remove a fan and replace it ?
2. Are there any tips on removing and replacing the fan ?
3. Is the fan keyed ? How ?
4. As the fan is a quite brittle alloy casting, is there a way of getting the fan off in one piece ?
Regards,
Ian