Mini excavator turntable wear. How do you know if it has any?

[munsters100]

How can you tell when buying a machine?

 

[Hendrik]

Slew ring wear is detected by lifting the boom off the ground and then moving the body with your hand, noting where the play is, with swivel boom machines there is usually a little in the swivel mechanism. Best off to use two people to check that, one to move the body and another to look how much slop is in the slew ring.
If there is any up down wear in the turntable you measure that by placing a dial gauge between the undercarriage and body and then using the boom to push the body up.

 

[OldMule]

I have a kx121 with play in the turntable bearing. I just use it on occasion,will it damage anything else if I keep running it? Has anyone replaced one on a 121 or similar machine. Looks like it would be a big job.

 

[accumac]

It is very dangerous but I stand beside the machine and operate the handle closest to the entry area to drop the boom or dipper to the ground then watch as it pressures down to the ground to lift the body (house) off the H-frame (track frame). If the tracks lift instantly off the ground then the bearing is probably good for up and down play. If there is any movement of the house,(upper body) before the tracks move up then you have to bend down and watch the turntable bearing to see if that is where a gap opens up between the top and bottom of the bearing. I am usually inspecting machines by myself so this is my method, it is much easier to check it with another person watching the bearing while you operate the boom. Any vertical play is not good, if it is 1/16" I would note it but not condem the bearing. However the hardened surfaces of the bearing could be gone and it could start to get worse quickly. This is only for vertical wear. Look for grease to be pouring out of the bearing (bad seal). also on larger excavators, I have seen lots of oil pouring out of the swing bearing because the swing motor seal blew out. The side to side play in the gear teeth could be excessive, however I don't think know that there is a definate rule of thumb, if it has a lot of side to side play it will make the excavator harder to zero in on the bucket target as it rocks to a stop. I also like to check the swing brake at this time. When I operate the swing, it should smoothly and quietly come to a stop when you center the swing control. Any noises or chattering or no stopping are usually expensive swing brake or hydraulic motor repairs. Look under the center of the machine for leaks from the swing motor seal or as mentioned before oil leaking from the turning table bearing could be from a bad swing motor seal. Good luck!

 

[John C.]

Anything over 0.070 up and down is worn out. Swing brakes do not stop the house from turning. They only hold the house in place after the controls are all released for about 7 seconds or so. Swing motor pinion leaks show up on the swing bearing and drip down on the carbody. It is usually very obvious. There is nothing you can do about free play between the ring gear and swing pinion gear short of changing both. Not really an economically feasible option on a mini excavator.

Good Luck

 

[DiamondConcrete]

I have a kx121 with play in the turntable bearing. I just use it on occasion,will it damage anything else if I keep running it? Has anyone replaced one on a 121 or similar machine. Looks like it would be a big job.

What year machine????

 

[Bubbles]

really old thread but popped up in a search and i have the same question as OldMule...curious if it will harm anything else or become dangerous to operate if one keeps running a machine with play in that bearing.

Also curious what it costs either for the parts to replace yourself or to have a tech do it (also on a 121)