We have a Bobcat 335. Last summer the 16 bolts that go through the swing bearing and bolt to the cab all snapped. It was our first go around with this and we ended up drilling/extracting/taping them all and replacing them with the cab on the machine. Well, actually we got 13 of the 16. Everything seemed fine, then yesterday the operator heard a loud bang and the bolts all broke. Probably had less than 50 hours on the machine since we replaced them at the end of last summer. I am considering two reasons this may have happened. One, we didn't use loctite, or torque the bolts in all to the same torque rating. Perhaps the bolts worked themselves loose and caused them to fail. Two, the bearing is going bad and bound up while rotating and caused a failure. Either way, we will now need to go through the procedure all over again. This time I am highly considering lifting the upper structure off the bearing to do the work. If we are going through that trouble I am also thinking maybe I should replace that bearing. Two questions: 1. Why do you think they failed like that? 2. Is there a good aftermarket place anyone can recommend to get that big bearing?
Look at the bolts. Did they shear clean or look like they backed out got chewed up a little then snapped. What grade bolts did you go back with ? And you didn't get all the bolts extracted and replaced. Its not a common fail but it does happen. Worn gears, slew bearing even the operating conditions and operator can be in the equation. Failure analysis on something like this is kinda hard not being there first hand other than the above mentioned. But just take into account that any slack in bearing, bolts and ring gear is really multiplied when swinging the weight
Good day A common cause of bolt failure is when the bed that the ring mates becomes distorted, spinning the ring against the surface using engineers blue should check it out. Attached some information that may be of help. Kind regards Uffex