Loose center or bad brake?

[deeredriver]

My excavator will not completly stop after letting go of the sick. It has a little back and forth rocking, not real bad but anoying. Is this the wear in the turntable bearing, or a swing brake? I can not realy notice it working, but when I go to hook up a different bucket is when it seems to realy show. Thanks!

 

[Wulf]

On a modern excavator when you let go of the swing control lever the spool in the control valve will neutralise and then the check valves and relief valve in the swing motor will stop the machine swinging. There is some over-run designed into the system to reduce the shock and to stop the machine smoothly. There is also a swing brake to hold the machine on slopes etc.

If there is a lot of side to side rocking it could be clearance between the pinion and the circle gear and the planetaries in the swing box. If you extend the stick and bucket and stop the engine you can check the clearance by physically pushing the side of the bucket, its hard to say what is normal as every machine is different.

Did you check swing pressure, also is the machine getting worse/deteriorating or are you new to the machine?

 

[deeredriver]

I extended the stick all the way and shut it off. I have about 1-1.5" inches of play. How bad it this? It is a size 200 size machine. I guess there is no way to fix this without a new turn table bearing? Thanks!

 

[dayexco]

1.5" of side play does not seem out lf line to me. wouldn't your bearing play be up and down? not side to side? set the excavator on a hard surface. have someone stand along side the machine, set the bucket on the ground, slowly raise the machine up, you can see how much play there is in the bearing.

 

[Wulf]

If its only 1.5" at the bucket end you must be referring to the play in the circle bearing? dayexco's advice is correct to ensure that the machine isn't rocking on the tracks, or the boom foot pins etc. but the most accurate way to check the bearing is to use a dial gauge and a magnetic base attached to the carbody with the dial gauge plunger on the upper house. The manufacturer will have a procedure for checking it in three or four places around the bearing and a spec for the allowable movement.

Sometimes if a bearing is failing you can see shiny metal particles in the grease when you grease it as the hard surfacing deteriorates.

How many hours are on the machine?

 

[deeredriver]

Don't know hours, as meter was chaged a long time ago, and I am the 3rd owner. There seems to be no up/down play in the bearing when I had someone operate the controls for me. I guess I will just get use to the slack. All I ran before was small rumber track machines. Thanks for the help!

 

[mflah87]

I had an old 235 that would move a good foot or so. That would be a bad bearing. But an 1.5" of play should be fine. A new bearing for that machine would be some big bucks. Never mind the money it would cost you in downtime.

 

[RonG]

I would consider 1.5" of play to be new machine specs as measured from the fully extended bucket tip.1.5' is not uncommon on older equipment.
I have seen that much play in some of the worn backhoes I have run over the years,you had to time your swing to drop the bucket in the hole you were digging as it went by or else you had to sneak up on it from the other side.
It seemed like the Case 580/680 etc. were the worst because the rest of the machine was robust enough to keep running so they never seemed to get in the shop long enough to get repaired properly.
Unless there are other indications of troubles it doesn't seem to me that 1.5"s is out of specs at all.Ron G

 

[ROV Tech]

When slewing the machine, and you put the joystick to neutral, the machine will just come to a slow stop (on level ground). The brake will only come on if you flick the manual brake switch.
So depending on the terrain the machine will still swing, if you have not applied the brake.
If it still swings and you have applied the brakes, then yes your brakes have failed.
However I have seen times when the machine wants to keep slewing in one direction ( no brakes applied ), and will not stop. This was a hydrulic problem.

If you have applied the brake, and it still swings from side to side, then yes you do have some play between your slew ring and slew box pinion ( but all excavators do ).
Just another one to think about, just make sure your boom/ stick bushes ( shoulders) or shims are in place. I have seen very excessive movement due to shoulders on the boom bushes broken off.

Duff

 

[digger242j]

I have seen that much play in some of the worn backhoes I have run over the years,you had to time your swing to drop the bucket in the hole you were digging as it went by or else you had to sneak up on it from the other side.
It seemed like the Case 580/680 etc. were the worst because the rest of the machine was robust enough to keep running so they never seemed to get in the shop long enough to get repaired properly.

Ain't that the truth!

I just tell people that the machine has a new computerized system--it automatically hunts back and forth until it determines the center of the hole, then it drops into it...

 

[deeredude]

1.5" of side play does not seem out lf line to me. wouldn't your bearing play be up and down? not side to side? set the excavator on a hard surface. have someone stand along side the machine, set the bucket on the ground, slowly raise the machine up, you can see how much play there is in the bearing.

we just changed out a swing bearing on our 160, with the bucket off the ground, you could actually just lean up against the dipper and the machine would swing back and forth. not real hard to change a swing bearing if you have acces to an overhead crane.

 

[dayexco]

we normally take the excavators that do the digging, and put packwheels on them at about 4k hrs....packwheels raise hell w/slewing rings....BUT, if they're greased as per spec..."knock on wood"....we've never had to replace one

 

[NWH]

there are spring loaded friction disks in your swing drive motor.
these could be worn out , broken springs or you may have a pressure problem
The way this works is when the swing control lever is moved , pressure is applied to release these disks simialar to a hydraulic clutch on a motorcycle
or in a truck. Link-belt and Case have a switch to hold the disks open for
" free swing " operations. I have never seen a need for this.

 

[KenAl]

On Deere 200 series machines the swing braking is done by when letting go of the lever the swing spool in the control valve goes back to neutral as well as a brake spool in the swing motor that blocks the flow of oil going back to the control valve. As mentioned before, the crossline relief takes over and relieves the oil to the low pressure side. There are also make up poppets that will pull oil from the return passage of the valve bank and thus stopping any cavitation. The swing brake as in discs is just for parking. It comes on after any and all upper functions are returned to neutral. (joysticks back to middle position). There is about a 4 to 5 second delay in the brake coming on. Bad braking is usually also poor swing power. I have seen the make up poppet seats have debris pounded into them and a worn out motor allowing port plate seperation. A case drain test will determin this.
1.5" of play at the bucket stretched out would be fantastic cosidering bucket to stick to boom to deck to swing pinion to gear reduction play.

 

[RonG]

Link-belt and Case have a switch to hold the disks open for" free swing " operations. I have never seen a need for this.

The ability to disable the swing brake helps a lot to smooth up the loading cycle for instance when loading a truck.You will spill a lot less material if you happen to be working in an area where that may be desireable.
I worked for one company that thought their 2800 was broke because they didn't know what the lever was for that controlled the swing brake.I am pretty sure it said "swing" on it too.We also had a 2650 but it didn't have that capability.Ron G

 

[Countryboy]

Welcome to HEF KenAl! :drinkup

 

[richardcatdaddy]

subject

We have an older Liebehr trackhoe.When you let go of the stick to stop a swing forget it.It just keeps right on going round and round till you stop it.Makes it a nightmare to load cause you got to constantly adjust to keep the cab straight.