No Fly wheel,
These are also well engineered, but dont free wheel like the K4. The 0-6-0 is a solid engine, powerful and good detail. There was only one issue with the original run versions - the gearing could cease up. It was a really simple problem, and it happenned to mine right out of the box. Basically the metal axle gear is very firmly slipped onto the cente drive axle. Its tight just as it is. However Accucraft in addition have a grub screw that screws down into a threaded hole in the steel axle itself (this this is hugely robust drive). The problem was that this grub screw was not tightenned into the hole. I suspect several models went out with the gear tightly placed onto the axle and the grub screw just left in place waiting to be tightenned into the axle. The bind was caused when the end of the grub screw would snag the inner gearbox casing, sometimes pulling the grub screw out and jambing between the gear axle and the gearbox cover. It was a real easy fix and the bind doesnt seem to cause any damage. The gearbox is all metal, including the main axle gear.
I wouldn’t be surprised if many models out there have never had the grub screw tightened and dont bind anyway, or the grub screw fell out and is lost. Doesn’t matter, the axle gear was a tight fit anyway. If you experience some binding, all you need to do to check is remove the screws to take the bottom cover off the gearbox (no need to pull the loco apart), and slowly rotate the axle till you see the grub screw hole at the side of the gear wheel, check that its wound all the way in. You may find that you need to slowly move the axle relative to the gear to try and find the threaded hole in the axle to aline it all. If the grub screw is gone, look around the grease to see if its glued itself to the insides somewhere.
David.