Has anyone had swing problems with one of these?One I'm working on makes a terrible noise when the joystick is released and the machine is slowing down.It will vibrate the cab windows realbad just before it stops.
im no mechanic or anything, but it sounds like the brake to me. what part of iowa are you from?
I'm from Baxter,about 35 mi ne of Des Moines.I have checked the brake out and it works like it's supposed to.Have had gears ,planetaries,brakes all out and can find nothing.Have had motor checked and it's good.
Are you talking about when you have the swing full tilt and were to release the lever back to center, then it makes noise?
A couple of Kobelco's that I've had made a pretty severe noise if the swing pinion got low on grease. There should be a small access plate in the battery box, open it and squeeze in 3 or 4 tubes of grease, swinging around as you do it. That fixed the squall on my SK220 MkIII and 290 Mk6.
When swinging as fast as it will go and release the joystick you can feel it vibrating and as it slows the vibration slows and gets louder.It can be felt in the ground.We had all the gears out and filled everything with grease.Thanks for the replies.
Got it. First of all, I'm not an excavator operator, maybe some real ex ops will correct me if I'm wrong, but I don't think swinging full tilt and then just let go of the joystick to stop is proper method of operation. The reason being is because of the vibration your feeling. When your swinging, your sending oil from the control valve, through the swing motor, then back to tank. When you release the lever, while swinging, the inertia of the machine swinging will continue the swinging motion and turning of the motor. The motor now becomes a pump, trying to move the oil that's in it, but the oil can't escape the lines because the centered control valve has the ports blocked. The result, the counterbalance relief valve between the two swing hoses opens and allows oil to re-circulate back through the motor, all being done under very high pressure caused by the weight of the swinging machine. Most swing motors on large machines are axial piston motors, and each piston is cramming the oil out of the motor with each rotation, forcing it through the counterbalance valve. There is a slight pressure relax between the output of each piston, therefore, all this happening in real time will be a noticable "vibration". My thoughts are that when you are swinging full tilt, you should slowly and progressively release the swing lever until you reach the point you want the machine to stop. At that point, you have the lever centered, with no vibration.
Usually swing motors have cross over reliefs. Basically they relieve into the input side of the motor and the oil just goes around in a circle with the pressure side at high pressure and the input side at low pressure. The relief pressure is usually set from a few hundred to a thousand pounds less than the main relief on the main control valve. Lately I've seen Komatsu excavators with a single relief and a switching valve that shifts according to the oil input or direction of swing. Sometimes the cross overs will make a lot of noise and vibration when the uneducated crank it tight hoping for a more positive swing. I don't recall seeing this in the Kobelco line although they do have a tight swing. Counter balance valves from my experience are used on travel motors and basically prevent the machine from running away when traveling down steep grades. High pressure on the output side of the motor shifts a throttling valve in the motor to close the output down and prevent the motor from freewheeling down the hill. My guess from the descriptions agrees with the grease in the swing pinion tub. I have seen Kobelco only loading a little bit of grease there from the factory. At any rate, check and fill the grease as recommended and if the noise doesn't go away then check the swing pressure. I have seen the same problem in the Rotec bearing on old machines going bad.
The swing cross over reliefs are set according to the service manual as are the main relief valve.The grease has been cleaned out of the bearing area as much as possible and refilled with grease.Found out this thing will make the same noise when moving slower than full speed when swinging.To me this doesn't sound like a bearing going bad.I had some help awhile back and pulled everything out -swing motor,brakes,and pinion.Setting on level ground I can push the machine completely around without a noise in the bearing.Thanks again.
Huh? Are you saying with the machine on level ground that you can push the bucket by hand and make the machine rotate?
Yes-with stick extended,engine running and operator inseat to keep the brake released by momentarily activating the stick function,once you get it to move it isn't to bad.
Well, that kinda explains the first "huh". I was wondering how you were able to rotate the machine by hand since it has a spring applied swing brake. Now the second "huh"; I was unaware you could release swing brake by activating stick function. Seems I'm sufficiently confused.
The swing brake will release for approximatly 6 seconds when you activate the stick and it will also stay released the 6 seconds when the swing control is released to neutral.
OK, you have narrowed the noise to the swing motor or the swing reducer. I have seen the bottom bearing go out in the swing reducers of many excavators. Basically all the metal flashing from the gears and any foreign material gets to the bottom and sits in the bearing. The drain for the reducer is usually above that bearing and there is no way to drain the junk out. Eventually the rollers start cramming the junk into the races chipping away the hard stuff and then you get vibration when enough race is gone. You should find some metal in the drained out though. If you have the swing reducer out it should be a quick teardown to check out the gear works inside. ATCOEQUIP The swing brake is released when any function is operated. It resets after nothing is operated for approximately seven seconds. It actually doesn't stop anything. It's just a parking brake.
That's pretty cool, JohnC...didn't know that. I was aware the brake was not in play when operating swing, and only takes hold when stopped.
The swing reducer has been completly taken apart and checked the gears in both planetaries and bearings,motor has also been torn down but no problems with either one,no metal found in gear case,filters or motor housing.Motor was also sent to hydraulic shop to be checked -they found nothing wrong.Thanks
Interesting problem you have here. I'm no excavator expert, John C has far more knowledge of them than I. But the problem intrigues my curiosity, as we can't avoid the obvious. That is; you have a noise/vibration that has to be caused by some component of the swing operation, yet, you have had the whole swing gear apart and find nothing faulty. The obvious being; if nothings faulty, then why the noise/vibration? The only logical answer can be we're either missing something or not looking in the right place. This is all assuming the slew ring bearing, the bull gear, and the slew ring teeth are all good and not the cause. Let's noodle through the logic of what we know so far. Quote: Kith Quote: Kith Quote: Kith Do you mean when swinging? Or, when swinging after you release swing lever? Quote: Kith Quote: Kith Did you actually test this? Did you, have the operator bump the swing lever, then you pushed the bucket and made it swing, and then 6 - 7 seconds later the brake activated? Isn't that the way it should happen? Help me out here John, is that the way it should work?
I'm thinking he had the swing machinery out of the machine when he pushed the house around. There is no way that he could have pushed through the reducer and the motor by hand. I would suggest plumbing into the swing brake line though and seeing if pressure is being let off and the brake applying as the joy stick is moving back to neutral. Link-Belt used to have a problem with the swing brake when the alternator was not putting out enough voltage. The swing brake partially applying was the give away that the alternator was on the fritz. I don't remember Kobelco working that way.
Quote: John C Your thinking exactly what I'm thinking John. Is it possible that we are losing brake pressure when releasing swing, and the springs are trying to apply brake? I would think that might cause a chatter.
The swing brake was ruled out because we took one of the cross over reliefs apart and removed everything inside ot it.Machine would only swing one way and would free swing when control was put in neutral until the brake came on.It did not make any noise when this was done,which makes me think it's in the valves but nothing shows any damage from the pounding that something has to be taking.
The swing brake solenoid might not be getting a high enough voltage to fully open and build full pressure to release or it might be releasing too soon. A gauge in the line will either confirm that problem is not there or show it is. It's worth a try. You cannot apply enough force by had to make that brake chatter. So what are the swing cross overs set at?
The reliefs are set at 4600psi,set them down to 3400 psi and noise is not as bad.I am almost positive these valves are the culprits ,but can't figure out why.
What is the proper relief pressure spec from Kobelco?
At least you made a change and now I think you might be right. If I remember right the valves are cartridges that screw into the top of the swing motor. In the Komatsu excavators you could take them apart and you would find a cone that fits into an orifice. If you examine the cone carefully you will see an out shaped ring on it where it has been riding in the orifice. If so you need to purchase a new cartridge. The orifice and the cone are shot. It was common in Komatsu a few years back but it usually only causes a mushy feeling swing. But it might be worth checking anyway.
ATCO-The pressure spec is 4600 psi. John C.-On this machine the control valve mounts right on the swing motor.It has the cross over valves,the shockless valves,and the spool that controls the swing.I have had the valve completely apart,nothing shows any damage or excessive wear.I'm about to order the control valve and hope it cures it but I would realy like to find something. Thanks again.