4625sx Eaton 70344 Hydrostatic pump Trunnion/Control Shaft seal leaking. In a post on the Bobcat Forum - post number 20417 , they refer to o-rings on the shaft. I have replaced the Trunnion Seal, located at the top of the shaft, but still have a leak. Does the shaft on my pump have those o-rings that I can not see until I remove the shaft? How do I remove the shaft? ps. I've updated my profile to free html per the FAQ, but can not get the HTML to work. Have tried Explorer, Chrome and Firefox - all no joy on the html.
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Update: Just disassembled the Eaton 70344 piston pump, the forward pump of my Gehl 4625. The trunnion seal was leaking oil. I had recently replaced the trunnion seal, but it still leaked. So I decided to take the pump apart, hoping there was a worn o-ring on the trunnion shaft inside the pump housing, but there was not. I also thought the trunnion shaft had been damaged or worn; however it looked fine. So now not sure what I'll do. Probably order and install a seal kit as long as I have the pump apart. And then have it pressure tested - I don't want to go to all the work of install until I know the pump is working and leak free. I would like to pressure test myself, but would need to research how to do that and equipment needed. Does anyone know how to pressure test a pump and equipment needed?
Not sure how you would go about pressure testing it, it could be done though. Those seals should only have charge pressure against them, so around the 100 PSI mark at a guess.Update: Just disassembled the Eaton 70344 piston pump, the forward pump of my Gehl 4625. The trunnion seal was leaking oil. I had recently replaced the trunnion seal, but it still leaked. So I decided to take the pump apart, hoping there was a worn o-ring on the trunnion shaft inside the pump housing, but there was not. I also thought the trunnion shaft had been damaged or worn; however it looked fine. So now not sure what I'll do. Probably order and install a seal kit as long as I have the pump apart. And then have it pressure tested - I don't want to go to all the work of install until I know the pump is working and leak free. I would like to pressure test myself, but would need to research how to do that and equipment needed. Does anyone know how to pressure test a pump and equipment needed?
If the shaft is damaged, you may need a speedy sleeve or something to take up any wear.
After further inspection the shaft has slight visual wear, but I'm a hobby machinist and could detect no measurable difference in diameter within a couple 10 thousand's using a micrometer. However you can feel a very, very slight wear on the shaft. Questions: Would anyone recommend turning the shaft down on a lathe in that area, braze the shaft back up and then turn it down to exact dimension? I've heard of that being done for shaft repair before. Any special type of rod to use?Not sure how you would go about pressure testing it, it could be done though. Those seals should only have charge pressure against them, so around the 100 PSI mark at a guess.
If the shaft is damaged, you may need a speedy sleeve or something to take up any wear.
Honestly, a little wear that you can hardly feel, i don't think would be an issue, the new seal should seal against the shaft.After further inspection the shaft has slight visual wear, but I'm a hobby machinist and could detect no measurable difference in diameter within a couple 10 thousand's using a micrometer. However you can feel a very, very slight wear on the shaft. Questions: Would anyone recommend turning the shaft down on a lathe in that area, braze the shaft back up and then turn it down to exact dimension? I've heard of that being done for shaft repair before. Any special type of rod to use?
Could using a different type of seal help prevent leaking? I wonder if something like hydraulic seals with an energizing ring could be used. Lip seals use the pressure behind them to seal, the more pressure, the harder the lip pushes agains the shaft.
I have no idea if that is an option, possibly a seal shop would.
Actually, I believe it is a lip type seal. Has a spring inside it to grip the shaft. I'm going to check the bearing and measure the shaft around the bearing; maybe there's too much play there causing the leak. Another guy also said to check the case drain hose; said if the case drain hose is for some reason plugged; it might be causing my leak. I'd post pictures, but can't get this forum to work. Everytime I post I have to hit Preview and then back to Edit mode. It won't let me HTML mode, I've got my profile settings set to free html; but not working...Honestly, a little wear that you can hardly feel, i don't think would be an issue, the new seal should seal against the shaft.
Could using a different type of seal help prevent leaking? I wonder if something like hydraulic seals with an energizing ring could be used. Lip seals use the pressure behind them to seal, the more pressure, the harder the lip pushes agains the shaft.
I have no idea if that is an option, possibly a seal shop would.
Youa re right, lip seals have the spring, i'm wondering if you can get one with more tension.Actually, I believe it is a lip type seal. Has a spring inside it to grip the shaft. I'm going to check the bearing and measure the shaft around the bearing; maybe there's too much play there causing the leak. Another guy also said to check the case drain hose; said if the case drain hose is for some reason plugged; it might be causing my leak. I'd post pictures, but can't get this forum to work. Everytime I post I have to hit Preview and then back to Edit mode. It won't let me HTML mode, I've got my profile settings set to free html; but not working...
Checking the case drain filters if fitted is a good idea, even a gauge on the charge pressure port isn't a bad idea. Ensure it's not too high.
Shaft play is a possibility, hopefully it is something simple.
How do I tell which hoses are the case drain hoses? Does just the hydrostatic pump have case drain or do hydraulic motors also have case drain - I wouldn't think so?? Since it's a tandem pump does each pump have a separate case drain hose or just a single hose off one of the pumps? Where does it drain to?Youa re right, lip seals have the spring, i'm wondering if you can get one with more tension.
Checking the case drain filters if fitted is a good idea, even a gauge on the charge pressure port isn't a bad idea. Ensure it's not too high.
Shaft play is a possibility, hopefully it is something simple.
If you look at the drive motors, most have 3 hoses, two large ones and one small one. The small one is the case drain. The internals of a drive motor are never fully oil tight, they have internal leakage that flows to the case drain port. It's also used to cool the motor as when oil goes out of this port, more oil needs to come in to replace it.How do I tell which hoses are the case drain hoses? Does just the hydrostatic pump have case drain or do hydraulic motors also have case drain - I wouldn't think so?? Since it's a tandem pump does each pump have a separate case drain hose or just a single hose off one of the pumps? Where does it drain to?
As for the pump, some have this line connected to the pump. Inside the pump is held at charge pressure to replace the oil that is lost through the case drain ports on the motors.
If you checked the charge pressure, you can see if it's within spec or too high making the seals leak.
Thanks Tazza I found them. Starts at left motor goes to the front hydraulic unit then to the right motor and then back to the tank. They are daisy-chained in that fashion. Do you suppose I could unhook the beginning beginning furthest from the tank, take the cap off of my tank and blow air through the house to make sure it is not plugged? Or would you be able to blow air through all of those hoses motors and pumps?If you look at the drive motors, most have 3 hoses, two large ones and one small one. The small one is the case drain. The internals of a drive motor are never fully oil tight, they have internal leakage that flows to the case drain port. It's also used to cool the motor as when oil goes out of this port, more oil needs to come in to replace it.
As for the pump, some have this line connected to the pump. Inside the pump is held at charge pressure to replace the oil that is lost through the case drain ports on the motors.
If you checked the charge pressure, you can see if it's within spec or too high making the seals leak.
Air should be able to pass through both, but never hurts to try one at a time.Thanks Tazza I found them. Starts at left motor goes to the front hydraulic unit then to the right motor and then back to the tank. They are daisy-chained in that fashion. Do you suppose I could unhook the beginning beginning furthest from the tank, take the cap off of my tank and blow air through the house to make sure it is not plugged? Or would you be able to blow air through all of those hoses motors and pumps?
As it's linked back to the hydraulic tank, they won't be causing hugher pressure in the pump though. Still good to check that they are clean though.
