Sideways play due to gear clearances: any remedy?

[Justin Payne]

Hello all. I own a Kubota U50-3@ year: 2006. There is some sideways play in the swing mechanism. I have had off the cover plate revealing the ring gear and swing motor gear. I lifted the bucket off the ground and had a friend push on the bucket the back and forth while I looked at the gear mesh. There was hardly any rotational movement of the swing motor gear. Almost all the sideways play is the result of play/clearances between the gear teeth. I see the gear teeth (specially the gear teeth of the swing motor gear) are somewhat worn. There is a clear notch along the perimeter of the wear surfaces. (see photo).

I would be very costly and time consuming to change the ring gear and swing motor gear. I therefor have the idea that if I could move the entire swing motor slightly outwards towards the ring gear, the gear lash /gear teeth clearances would decrease, and the sideways play of the excavator would decrease. I don`t know if the free holes in the upper chassis holding the swing motor give any play with the given bolts.

I hope I have managed to describe the situation and my thoughts so that people understand. Has anybody got any comments to this? I would be very appreciative.

 

[Vetech63]

Your swing gear casing is going to set into an ID that is made for it. There will not be any play to do as you are thinking. They have to fit tightly as the bolts alone would not hold the assembly steady for long and it would eventually shear the bolts off. Unfortunately, the only way to correct the problem is to replace the swing pinion and ring gear.

 

[Justin Payne]

Hello Vetech63, Ah, yes, of course, I see now from my own photo what you mean. The swing motor fits snugly in a hole restricting any sideways movement. Ok, I will just have to live with this sideways play I guess... Thanks for the swift comment anyway!

 

[Justin Payne]

If one could get hold of a slightly "over-sized" swing motor gear pinion that is over sized to compensate for wear of the ring gear, then that could save one for changing also the ring gear. But I guess that would not be possible to obtain. And I guess it is somewhat time consuming to change this swing motor gear pinion..?

 

[Vetech63]

No oversize that I have ever heard of. If your ring gear is worn as much as that pinion, then replacing the pinion alone will only work for a short time...…...then the new one is worn. The teeth on both have to have the right fit to last long term. If this is just a personal use machine, then I would live with it, especially if you are not making a living with it.

 

[John C.]

I've seen that before on Kubota excavators. The metal in the gears is soft and all of those machines that I have inspected were like that. It is an aggravation for some operators, most operators that don't own the machine that I've been around though, really didn't care.

 

[uffex]

Good day
I can appreciate your concern with regard to the back lash it is important to monitor such wear before disaster strikes, I would suggest a couple of strategies to adopt 1- contact the dealer for the wear tolerances normally these are by measuring the movement at the extremities of the swing ring 2- The majority of the wear appears to be by the drive gear maybe just replacement of this part may save the day. I attach a couple of informations that RothErde provide that may give you some help.
Kind regards
Uffex

 

[uffex]