I was using my E120B to remove trees and I took lunch break and came back out. Worked it for about a minute or so and started to get a noise from the swing motor, when I would start to swing and then release the lever it would slow down very little then after 3 seconds the swing brake would engage and stop the unit. It almost sounds like a grinding noise when I start to swing the hoe, more noise the harder I accelerated the swing. Once it gets up to full swing speed, it is quite. I am thinking there is something messed up with the dynamic swing braking….but could this make it have a noise when it starts to swing? Could the 2 valve on side of swing motor be stuck open or shut….. any ideas would be great, thanks.
Sounds like something in the brake or motor has come apart. Not sure why it would get quiet at full speed unless the brake is just finally releasing at full swing speed. Does it grind when you let off the swing control?
Good day nates90 As best to our information the actual braking of the swing is made by the swing motor reacting like a pump under pressure, the actual brake is more of a parking function holding the superstructure after it has come to rest. I guess the small valve which you appear to refer is that of the brake delay, pressure releases the brake whilst the default position is that of locked. We have some information on the issue if you need just contact us at Excatech.com Kind regards Uffex
An update, as I was tracking it to my shop, I put the arms all the way out and if I released the swing brake (parking brake), it would free pivot until the computer reapplied the swing brake (parking brake). I now the swing parking brake is good because it stops the machine in a hurry when the computer puts it on.
When you say free pivot do you mean it swings without touching the controls, kinda like a neutral?
Is there a free swing switch on that machine..?
Good day nates90 Your issues relate to that of the swing motor system and not that of the brake, we suggest that you test the swing pressures in both directions with the arm in the dig. Either your motor is kaput or one of the check valves have become damaged. If you mail a snap of the transmission we will try to identify the cause of the problem. This may be of help in diagnostics http://youtu.be/gVDRiO8vL-k Kind regards Uffex
Only way I can undo the swing brake (parking brake) is to start to swing left or right, then it has a 3 second delay for the dynamic breaking to occur before the computer puts the actual parking brake on. So, when I have the arms all the way out, I can start a swing then let off the control and it free swings for the 3 seconds until the computer applies the actual brake.
There's no computer that applies the brake on those things, unless its some kind of model I'm unfamiliar with. Hydraulic pressure goes to a brake disc to release it as soon as you start to swing. Once you let off the control it dumps the pressure which applies the brake. Nige correct me if I'm wrong but thats how most models I work on operate.
Sounds like a relief valve or control valve issue to me.
I know when I move the lever, I hear a click in the computer behind the seat, then when I let off the lever it clicks again. Then 3 seconds later it makes another click and thats when the brake applies.
The old plain hydraulic units often had a check valve and orifice, the check opened for oil to flow in and release the brake, when pressure went away the check closes and the oil flows slowly out through the orifice causing a short delay as Nates90 says to allow the motor to dynamically stop the swing before the brake is applied. Much softer stops and the brake wouldn't last long stopping the swing all day, you could roast weenies on it pretty quick. Yep, counterbalance valve, check valve, internal motor issue is my guess.
Good day nates90 Please check if the illustration is the same as your machine, according to our information there is no electrical connection to the brake release, this sounds more like a relay than a ECU - ECU switching is almost silent. Most excavators today release the slew - swing brake when operating the arm in, this is supposed to prevent overload when clearing material with the bucket side. We still have the opinion that your brake is functioning correctly, the root cause appears to be that of motor or relief/check valves. If you can confirm the transmission type we can help with better instructions. Kind regards Uffex
Yes, it looks close to that. It has 2 relief valves on the back side and two other valves, one on the left and one on the right.
As stated by others above the E120B does not have a computer. What you can hear is either the swing parking relay or the timer relay for the swing brake clicking.
Good day nates90 We suggest that you begin to trouble shoot in this way, If you have pressure measuring tools carry out what we described earlier if not ignore the brake issue and focus on the swing stopping - see animation try both to left and right. Depending on if the issue is in both directions we would recommend you remove the large allen plugs in the motor head, behind which you will find a spring loaded check valve, the seat forms part of the body so check this carefully. Do not just check the valve remember the seat I guess there will be two of these only damage to one will result in a slew stopping issue in both directions. (Please keep in mind to release any residual pressure from the reservoir before you dismantle any plugs). If the issue is only one direction it could be the relief valve if you send a photo we can be a little more specific. Kind regards Uffex
Good day nates90 A contact provided this illustration of the check valves in question, we believe that the parking brake is applying before the superstructure has come to rest, hence the noise and damage risk, if the check valves are OK the chance's are that you will need a reman motor. Kind regards Uffex
I took off the check valves, and everything looked fine. I took off the relief valves and they looked fine also. I then took the four bolts off the top of the motor and there are about 16 springs that sit in there own holder. Pulled one of the springs out and it has a lot of brass shavings in it. Took another spring out, same thing.
Good day nates90 That is in our opinion not good news as generally those coulor shavings come from a damaged motor. Do you have a repair shop near by that can dismantle and inspect the unit ? Kind regards Uffex