The thrust bearings are typically ball bearings. The only time I heard of conical rollers were the very old RailRoad adds of the 40's. Things go tits-up when a cage breaks and the balls migrate away from the radial load. Fortunately the shafts find a home cuddling inside some other bearing compartment until the plane lands.
It's like a bowling ball inside a washing machine. Best not to be in the same room with it.