Oil change of swing motor gearbox, Kubota U50/KX161

[Justin Payne]

Hello guys,

In my Kubota U50/KX161 norwegian maintenance schedual there is a point stating: "Oil change in driving gears and guide roller" (or something like that (this was a direct translation from Norwegian)) every 2000 hours. No further remarks or details of this in the operators manual.
Oil change in the final drives / track motors are listed as a separate point (with oil change every 500 hours) , so they are not what this point is about.

I guess the oil in the swivel motor gearbox/ slew gear could be one of the items they mean? Does anybody know with more certainty what is meant with this point? Has anybody here ever changed oil in their swivel motor gearbox before, and can tell me how it is done?

 

[Justin Payne]

Does anybody know if it is normal to sometimes check the oil level or change the oil in their swing motor gearbox at least?

 

[Nige]

The normal thing on an excavator would be to check the oil level in the swing transmission once every 250 operating hours, and change it every 1000 or 2000 hours. For machines that don't work a lot of hours that would be check the oil level every month and change it every 6 months or 1 year.

 

[lantraxco]

Can't speak to this machine but many of the mini excavators have no gear reduction on the swing, it's just a large hydraulic motor direct to the pinion gear.

 

[Justin Payne]

Thank you very much Nige and lantraxco! I will do some more research by dismantling some panels on the machine..

 

[Justin Payne]

I have investigated the swing motor. It is quite "tall" and the spare parts catalog also implies that it has a "gearbox" with planetary gears. (Please see and open the two pdf. attachments) But there is no oil drain or fill plugs!:beatsme:beatsme

Can it mean that the oil in there should last 4ever?? Or is it lubricated by hydraulic oil??

 

[lantraxco]

It looks like there's no seal on the motor, just the gearbox shaft. It also looks like the big bearing on the output pinion is open and must be greased from a fitting somewhere. Is there a small hose connected to the body of the gearbox section, I can't tell but it looks like maybe. So I'm guessing the gears run in hydraulic but can't confirm that.

 

[Justin Payne]

Hi lantraxco. Thanks for taking the time! No, there was no hose connected to the lower end (gearbox section). So-, does that mean that the gears run in hydraulic oil?

Here is a picture from below. No plugs here either..

 

[Justin Payne]

I see now that there must be some mistake/ mix-up with the exploded parts view of the gearbox section. (the exploded view and the list of parts do not coincide. Neither do the two exploded views (The entire motor versus the gearbox section) So I am guessing I have a different gearbox than this one.. Mine looks more like the small picture shown in the exploded view of the entire swivel motor. I have been searching the internet for information, but can`t find anything..

 

[lantraxco]

Well, your pinion gear looks good at least!

 

[AirBornOne]

In your picture.
The slightly proud plug looks like a drain/fill plug.As does the slightly recessed fitting.With an adjustment fitting just out of the orange circle,obscured by the rod or tube.
Dunno how you would access or reference an oil level though.
Usually the hydraulic fluid operates the motor and is separate from the gears.Gears need much more protection.
HTH
Jay

 

[Justin Payne]

Thank you very much for your tips AirBornOne! But: The plug you have circled is in the upper part of the body. Am I not right in believing that the gearbox should be in the lower part and the hydraulic motor is in the upper part of the body? So: Should not any oil fill/drain plugs for the gearbox be in the middle/ lower part?

 

[John C.]

Most of the minis run just a motor and if there is a gear box it is lubricated with grease. I have seen a grease fitting in the cab on machines this size to the right of where your right foot would normally be when you are running the machine. Other machines have a fitting to the right side of the boom that seems to go disappear into the machine. If they have a gear box with oil there will be a dipstick coming up through the tin work.

Let us know what you find.

 

[melli]

Swing (Slew) motor is all hydraulic as far as I know. There is no self contained gear box in swing motor (that has a self contained oil supply). There is a swing motor drive carrier at bottom, but from my machine's manual, it is just roller bearings. Through the 'swing motor drive carrier' is the drive shaft (gear on one end that turns house).
I'm pretty sure there is no port for changing oil there....
The swing circle gear/ swing bearing is attached to undercarriage, and the swing motor tracks along that...now, it does need greasing (every 8hrs according to my manual - I do it more often with house at different positions to ensure whole ring gear is well greased). My grease nipple is in front of house. Once every few years, I'll drop the access hatch underneath undercarriage (under machine, dead center). All my old grease falls off swing circle gear and collects on top of access hatch. We are talking 20pds worth...lol. I am prepared for it now when I remove hatch....

There is no swivel motor...the swivel joint is just a unit for dispersing pressurized hydraulic oil to drive motors and blade hydraulics. It is a mess of O-rings and seals to allow one to turn the house and use under carriage implements.


Aside: I just read why I don't have huge swing force...probably for good reason, but I read the cross-port relief valve on swing motor is 1700psi, well below 3000psi for other hydraulic implements. One of my gripes is the inability to bash sideways with force...lol