Author Topic: Fan  (Read 1924 times)


  • Jr. Member
  • **
  • Posts: 64
    • View Profile
« on: August 30, 2007, 04:31:06 PM »
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.

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 ?



  • Hero Member
  • *****
  • Posts: 3386
  • Why don't pictures ever work for me?
    • View Profile
    • Doug's Petteroid Stuff
Re: Fan
« Reply #1 on: August 30, 2007, 05:59:32 PM »
A good electric motor shop can probably replace the fan with something.

My fan is plastic but held on with the same key and snap ring as yours.

It's a Good Life, If You Don't Weaken