CAT 307 Swing Gearing Vent?

[Haymaker101]

Lot of great info and knowledge, thank you. If there is seals leaking or damaged, would I be able to visually see it from the outside or is everything internal? I’m going to get the excavator back to the shop where I can power wash and further investigate. I’ll add pictures this week. Thanks as always

 

[Nige]

John C makes a very good point about how difficult it is to drain a small swing transmission such as the one on your machine. Try removing the drain plug and leave the swing gearbox draining overnight to see how much oil comes out of it maybe.?
It would also be recommended to leave the filler cap off so that there is no chance of the gearbox sucking a vacuum as the oil drains out of it.

 

[Haymaker101]

Hey guys
So I have tried this 3 times now over the last couple weeks and just want to give you an update. I painfully Fill swing motor until it appears on the dipstick. Takes forever, maybe due to air?
I’ve been running machine for a few hours and oil overflows out the fill dipstick tube. I drain the oil from the machine, it takes roughly 15 minutes and I capture about 24 to 28 ounces of oil when measured out.
The book calls for 40 ounces capacity, but obviously you never get all the oil out when you do any oil change.
The machine is working and acting totally fine otherwise. I feel like I have a block air relief or vent of some sort? Anyone have any other ideas? Hydraulic oil in the rest machine is completely fine.
Also, there’s a roughly 1/2” pipe with a plug opposite the dipstick, can I fill the oil through there? Thanks

 

[Haymaker101]

Hey everyone, I reread all the suggestions and I think that I overlooked one of them. That is that the seal between the swing motor and the Swing Drive is most likely leaking hydraulic oil up through the fill dipstick. I think I am going to get hydraulic oil dye to see if that is the case. also, it sounds like I can unbolt the swing motor from the swing drive and see if it leaks oil, correct?Thanks for everyone’s help

 

[uffex]

Good day
Your suggestion is good, may I also suggest you plug one main line to pressurize the remaining line that will replicate working conditions. See attached
Kind regards
Uffex

 

[uffex]

Omitted to mention, a common tip is to warm the lube aids filling via the small fill holes

 

[Bluox]

Hey guys
So I have tried this 3 times now over the last couple weeks and just want to give you an update. I painfully Fill swing motor until it appears on the dipstick. Takes forever, maybe due to air?
I’ve been running machine for a few hours and oil overflows out the fill dipstick tube. I drain the oil from the machine, it takes roughly 15 minutes and I capture about 24 to 28 ounces of oil when measured out.
The book calls for 40 ounces capacity, but obviously you never get all the oil out when you do any oil change.
The machine is working and acting totally fine otherwise. I feel like I have a block air relief or vent of some sort? Anyone have any other ideas? Hydraulic oil in the rest machine is completely fine.
Also, there’s a roughly 1/2” pipe with a plug opposite the dipstick, can I fill the oil through there? Thanks

Pull the plug out and see what happens.
Bob

 

[Haymaker101]

Hey everyone,
I know it’s been over a year but hopefully this topic can come back to life.
I’ve been adding oil as needed but brought 307C home and put it in the shop to fix.
Removed hydraulic lines and swing motor.
Does anything in the picture look out of the ordinary? The O-ring felt a little “flat” to me.
I assume next would be to clean and remove the bolts around what I would call the gear box. Please advise, thank you!

 

[heymccall]

You took apart the gear box. Wrong component.
Your leak is (should be) the seal on the swing motor output shaft.
At the arrow.

 

[heymccall]

Oil from above the arrow (hydraulic oil) is transferring to the gear oil (below the arrow).
Unfortunately, that seal is only accessed by disassembly of the swing motor.

 

[Truck Shop]

Topic-check to see if that 307 is made in china--enquiring minds on HeF want to know.

 

[uffex]

Good day
A thought crossed my mind what grade oil are you using to the transmission?
Kind regards
Uffex

 

[Haymaker101]

Good morning,
Thank you for helping to continue to advise me on this.

I think last year when I made the comment regarding the oil coming out of the dipstick, it was mostly because I was overfilling it and then upon running it the oil maybe warmed up and expanded and caused it to come out the tube. Over the past year as I add oil no oil has come out the tube.

I am not losing any hydraulic oil. I have been adding caterpillar transmission oil as needed to the gearbox.


I am thinking that my next course of action should be to go after the 12 bolts and remove what I think would be called the gearbox? Then I would see if gearbox oil would be getting around the slew ring where there should be grease? Am I thinking through this correctly?

Also, no idea if it’s China made. Came from Milton CAT originally.

Thanks again everyone

 

[kenworth]

What year and how many hours do you have on the machine. According to the specalog for the machine from Cat, the swing gear box holds 1.5 liters of oil. That is about a quart and a half.

In my experience with swing gear boxes, they are all planetary units with very little room and no provision for cooling the oil. The oil will get warm and expand. The other issue is when filling the oil, it takes a lot of time for it to drain into the box and fill while expelling all the air caught under and around all that gearing. Draining and refilling the box takes time. The common issue while refilling is air burping up through the fill tube and making a mess. Then people pull the dipstick and assume it is full when it isn't. The other mistake is putting too much oil in the box figuring it will drop down some as it is used, and the box now expels the excess through the dipstick or the breather if it has one. Another issue happening on some machines is that the bottom bearing in the swing gear box may be lubed with grease and not the oil in the swing gear box. An operation and maintenance manual would let you know if that is the case in your machine.

A continuous flow of oil out of the breather or dipstick tube would indicate a leaking seal in the hydraulic motor which would force hydraulic oil into the swing gear box. It was mentioned above about the possibility of a case drain filter being plugged. No manufacturer that I have dealt with puts a case drain filter on the hydraulic motors. Cat puts a case drain filter on the hydraulic pumps. All case drains for the motors on machines that I have dealt with go to the machine return filters or the directly back to the tank.

Swing motors can be subject to very high pressures when the house is turning and then the control is moved to stop the turning. There are provisions in the motor to handle and vent that high pressure so that it doesn't damage the motor. A blown seal may be the result of a problem in that area of the motor. The motor itself may also have internal leakage on the seal plates or piston and barrel assembly that may cause high pressure in the motor case. If your motor is leaking into the gear box I would suggest a call to your local dealer asking if there are updates to that motor before going any farther. You might be able to unbolt and lift the motor out of the mount on the gear case and then use the machine hydraulics to turn the motor shaft and watch for a leak. Keep in mind though that with no load on the motor, it isn't likely to show a leak from the shaft.

Excellent Reply, thank you for the learning lesson.