Stuck bottom bracket.
I realise I am reviving a zombie thread here but as it was about the only place I could find any information on Burley bottom brackets I thought it might be helpful to the next person!
We recently purchased a Burley duet S/S and it's in a pretty sad state so it's being sent for shot blasting and powder coating, had to get all the components off first!
I removed the snap rings and as suggested above had at it with a dead blow mallet, made astonishingly little progress and got a very tired arm.
I eventually had a brain wave, popped a spare crank bolt in the axle and ran my sds drill with a masonry bit that fit inside the 8mm socket on the crank bolt (hammer only mode) the bearings and spindle came out in seconds, didn't even damage the drill bit!
Just a note, it doesn't come out as one assembly it's bearings that are push fit onto a central solid axle with a spacer in the middle.