Swing bearings "yes plural" popping bolts on Terex RT555-1 Cranes

[HATCHEQUIP]

Problem #1
Company that we have dealt with for years had me come look at a crane that they said the frame was flexing on. They set up that 555 "call this #1" and another that had came in from a finished job "call this #2. So 2 RT555-1 setup and leveled with levels, 4'x4' pads under out riggers both are rigged and equipped the same. Checked #1 for cracks or bends or just anything that could or might be different than #2. Stamped weight on counter weight for #1 is 200 lbs heavier, only difference we could find. Little history here #1 has just been purchased and they were dong a crane inspection certification on it, #s 2, 3 and 4 they have had for several years. Started doing picks and then maxing the chart and checking the computers against each other and load charts. I was comparing frame flexing and yes there is some but its looks the same for both units. But noticed #1s bearing moving, got a dial indicator on it. boomed it all the way up zeroed dial then boomed it down came up with .075. Had operator bounce it to see if it would keep that reading and it didnt, but noticed the bearing looked like it was really jumping forward. Measured the bearing would come forward .187 though it looked more to the eye. Picked a max chart load and the indictor went down from .075 to .110, cut the load loose boomed all the way back up and it zeroed out. Checked #2 and it didnt have enough to even bother putting the indicator on it. #1s bearings got play, bearing is made by Kaydon.
Both machines will do what there charts allow but they say #1 just feels like its going to turn over.
Problem#2
They are finding broke bolts in the swing bearings 1, 2 sometimes 3 at a time. Checked #1 and yes it has 2 popped bolts that we could see or feel.
Would like to hear thoughts from others especially similar problems with Terex 555s

Following is Kadons charts

Following from Terex
Procedure for Determining Slew Ring Wear on Terex Cranes
1. Place a dial indicator under the outer race of the bearing.

1. Apply a minimum downward thrust to the outer race and note the reading on the dial indicator, downward thrust can be applied by extending or lowering the boom to shift the weight to the front of the upper.

1. Apply a minimum upward thrust to the outer race and note the reading on the dial indicator, upward thrust can be applied by retracting or raising the boom to shift weight to the rear of the upper.

1. The difference between the readings obtained in steps 2 and 3 is the approximate internal clearance in the bearing. Compare the valve obtained with the values given for the bearing part number you are measuring.

1. When the measured value exceeds the value shown the slewing ring should be replaced.

 

[Nige]

They are finding broke bolts in the swing bearings 1, 2 sometimes 3 at a time.

Just on the one crane or different ones.?
Same bolts every time or different ones.? Are they marking the ones they replace.?
Maybe better to replace all the bolts in one hit rather than piecemeal.?
Different bearing manufacturers between crane #1 (Kaydon) and the rest.?
Got any good photos of the fracture face of some broken bolts.?

Not Terex but we had some brand-new Grove RT cranes (3 IIRC, all the same model) one time that gave all sort of issues with swing bearings. Grove downloaded the memory and tried to accuse us of overloading them but eventually the problem turned out to be that despite all the cranes being on their first job the swing bearing supplier had been outsourced to China. Don't recall them breaking bolts though. The foregoing is from memory but I can dig out more info on them if you want.

 

[CraneMechanic73]

It wouldn’t surprise me if the bolts were just a bad lot!

 

[HATCHEQUIP]

All four 555s are snapping bolts, didnt know about this problem until after we started diagnosing #1.
Dont have pics as the broke bolts we found in #1 were gone and didnt try getting what was left out, they are breaking right at the top of the threads.
They didnt save any from the other cranes or mark the locations.
Another thing is you cant see all the bolts until you set the upper off the bearing so if bolts are bad that you can see what about the ones you cant see.
Agree after this many on replacing all because the others have possibly been stretched or fatigued, something here is not right but id like to know whats causing it.
6 to 9000 hour cranes that your going to unstump to get to the bolts makes you think about replacing the bearing while there. Terex sells a kit for about $10,500 bearing and bolts. But a hook cranes a machine that can rack up the hours and not do allot of work unless it does some duty cycle, still think ill recommend replacing.

 

[Nige]

Had operator bounce it to see if it would keep that reading and it didnt, but noticed the bearing looked like it was really jumping forward. Measured the bearing would come forward .187 though it looked more to the eye.

That would worry the heck out of me, especially if it looked more to the eye. Sounds like the bearing is not long for this world, and it's good that there is a bearing kit that includes bolts.

Another thing is you cant see all the bolts until you set the upper off the bearing so if bolts are bad that you can see what about the ones you cant see.
Agree after this many on replacing all because the others have possibly been stretched or fatigued, something here is not right but id like to know whats causing it.

TBH under those circumstances I would suggest considering replacing the bolts in the other three cranes as well even though access is a pain.

 

[HATCHEQUIP]

Worrys me too.
Bolts are $2500.
Kit $10,500 includes bearing an bolts.
Im thinking replace it in all 4

 

[Nige]

Worrys me too.
Bolts are $2500.
Kit $10,500 includes bearing an bolts.
Im thinking replace it in all 4

A kit would make sense for all 4 machines TBH.
If it isn't worrying the customer I would humbly suggest they are in the wrong line of business if crane operations is their main work.

 

[HATCHEQUIP]

Oh it does, big time, thats why their trying to get a handle on it.
Large contactor with allot of cranes, crawlers and RTs as well as a fleet of dirt equipment

 

[Nige]

By the numbers you quoted in your OP the swing bearing in #1 is toast. How about replacing it first and take a good look at both the bearing once it is disassembled and the broken/unbroken bolts that come out of it.? That might give you a better handle on what is going on with the other three units.

is the Terex like a Grove in that you can get into the LMI memory and download full details of the lifetime loading/overloading history.? That might tell an interesting story.

 

[HATCHEQUIP]

These have microgaurd lmi"s And I dont know if these are new enough that its capable of recording past history. Will have to get the ser. #s and call my lmi dist. to find out.

 

[Nige]

These have microgaurd lmi"s And I dont know if these are new enough that its capable of recording past history. Will have to get the ser. #s and call my lmi dist. to find out.

All I can comment is that similar size Grove machines had that feature on them 15 years ago.