Removal of Key from a National Flywheel


The key of the engine had been butchered when someone had chiselled off the key head and for some reason had drilled a hole though the key into the shaft, I did not take a picture of the first attempt to remove the key which was by welding a large nut onto what was left of the key and using a bolt screwed through the nut then turn against the flywheel hub


After welding a nut onto the damaged key, the key snapped off were it had been drilled when pressure to the bolt was applied, no moment of the key was seen


To obtain as much welding area I could get, I lengthened and shaped a piece of key steel up to the step in shaft diameter

I obtained a piece of pipe with the inside diameter that would go over the smaller dia of the shaft so that it would slide up to the change in shaft size, I cut the pipe off about 20mm longer than the shaft length and cut a slot so that the extended key would slot in thus giving me a much increased welding area.

I originally was going to weld a larger piece of pipe with slot for key over the larger dia shaft hence the ground area on pipe 

I then drilled a 25mm hole in a piece of 12mm strap and welded that to the end of the pipe, then inturn welded a 25mm nut to the strap

I then cut two pieces of about 8mm strap for either side of the existing key between the flywheel and the pulling pipe and  without welding the shaft or flywheel welded the original key to the new key piece, the two 8mm straps to the keys and then the lot to the pipe

When all was welded and cooled down I tightened the 25mm bolt as much as I could using a length of pipe for more leverage - no movement was seen, then repeated heavy blows to the bolt head and more attempts to screw the bolt I could see the existing key starting to pull through the weld. cannot believe how tight it was in.

More welding above the key including a piece of round across the whole lot was added and the above procedure was repeated - slog the bolt, turn the bolt, sweat (as it was 36 deg C) and finally after much effort I could see slight movement, the procedure continued until it came loose.

Other than careless grinding by myself where I touched the flywheel no damage to shaft or flywheel occurs using this method and I doubt that I could have got the key out using any other method and yes no prize for saying I am a rough welder :-))