Woods backhoe cylinder leaking?

[Wayne County Hose]

Hercules Part# PS2700-40......5000psi rated...http://www.herculesus.com/home.php?cat=1069

The Hercules PS2700 series is an excellent piston seal. They, like any other piston seal, can be installed with a nick, burr, or twist which may take a little time to be a problem. Hercules is an OEM for most cylinder manufacturers. Many times when you purchase a seal kit from a dealer, it will come in a Hercules bag. John Deere is famous for this.

Here is what I would do. Extend the cylinder all the way. Make sure there is no weight or pressure on the cylinder. Slowly, remove the hose on the rod side of the cylinder, again, make certain there is no npressure in the line. Start the tractor, move the lever to extend the cylinder. Check the flow of oil out of the fitting on the rod side. If there is flow, hook everything back up. Go to the dealer and tell him exactly what you did. If there is flow, it verifies a faulty piston seal. No flow says your piston seal is probably ok. Granted this is a backyard way to do it, but unless you have pressure and flow gauges and a toolbox full of adapters and high pressure valves, it's the next best thing. Just be careful and if you aren't absolutely sure of yourself and what you are doing, either get help or don't do it.

Good luck,
Andy

 

[Mousefield]

Hi to all that responded. Some of this is a bit over my head. I will have time on the weekend to really study your responses and try and do what you have suggested. Just in the middle of a building project today and tomorrow. I should have some more info for you no later than Sunday.

This is what I had sent to the dealer.
As suggested I warmed the tractor up to its normal operating temperature and then worked the left lever that controls the swing cylinders and main? hydraulic cylinder.
I extended the backhoe all the way out and up. Opened the thumb all the way and curled the bucket so it was pointing towards the tractor. Thumb and bucket parallel to the boom.
Measured from the ground to a point at the top of the bucket.
May 18th
10:10AM 83 1/8 inch
12:05PM 72 ½
3:55PM 56 1/2
7:00PM 45
9:30PM 38 ½
May 19th
6:00AM 19 ½ also bottom of bucket 5 ½ inches from the ground.

Pics are of the small log that dropped the bucket down about 1 - 1 1/2 feet in 22 minutes.

Regards,
George

 

[shaley]

The Hercules PS2700 series is an excellent piston seal. They, like any other piston seal, can be installed with a nick, burr, or twist which may take a little time to be a problem. Hercules is an OEM for most cylinder manufacturers. Many times when you purchase a seal kit from a dealer, it will come in a Hercules bag. John Deere is famous for this.

Here is what I would do. Extend the cylinder all the way. Make sure there is no weight or pressure on the cylinder. Slowly, remove the hose on the rod side of the cylinder, again, make certain there is no npressure in the line. Start the tractor, move the lever to extend the cylinder. Check the flow of oil out of the fitting on the rod side. If there is flow, hook everything back up. Go to the dealer and tell him exactly what you did. If there is flow, it verifies a faulty piston seal. No flow says your piston seal is probably ok. Granted this is a backyard way to do it, but unless you have pressure and flow gauges and a toolbox full of adapters and high pressure valves, it's the next best thing. Just be careful and if you aren't absolutely sure of yourself and what you are doing, either get help or don't do it.

Good luck,
Andy

Good idea. What Andy is saying is to pressurize the extend side of the piston using the tractor while measuring the oil amount comming around the piston seal and out of the rod side (retract side). This will be the leak-by rate. But, like he said, be careful.

 

[AKKAMAAN]

Hi to all that responded. Some of this is a bit over my head. I will have time on the weekend to really study your responses and try and do what you have suggested. Just in the middle of a building project today and tomorrow. I should have some more info for you no later than Sunday.

This is what I had sent to the dealer.
As suggested I warmed the tractor up to its normal operating temperature and then worked the left lever that controls the swing cylinders and main? hydraulic cylinder.
I extended the backhoe all the way out and up. Opened the thumb all the way and curled the bucket so it was pointing towards the tractor. Thumb and bucket parallel to the boom.
Measured from the ground to a point at the top of the bucket.
May 18th
10:10AM 83 1/8 inch
12:05PM 72 ｽ
3:55PM 56 1/2
7:00PM 45
9:30PM 38 ｽ
May 19th
6:00AM 19 ｽ also bottom of bucket 5 ｽ inches from the ground.

Pics are of the small log that dropped the bucket down about 1 - 1 1/2 feet in 22 minutes.

Regards,
George

I think the leakage is within tolerances too!!

It is a small cylinder 2.5" bore with a 1.25" rod....and the leakage volume is the difference between the capped volume and the rod volume...as I posted before....3.68 cui per inch of CYLINDER DRIFT...

Questions:
Under what pressure was the test??
What length of cylinder drift did your test represent??

I assume about 3/4 stroke, which would be about 12" (full stroke is 15.5")....
12 by 3.68=44cui or about 723cc....sound like it is a lot, but over 20 hrs or 1200 min, it is only 0.036 cui per min or 0.60 cc per min
your test with the log would accordingly be about 1" cylinder drift in 22 minutes, which is about 0.17 cui per min or 2.74 cc per min.....

These leakage volumes is combined leakage through spool valve, piston seal, work port valves etc....

so IMO,it is NOT VERY BIG NUMBERS if pressure have been some where nearby max system pressure!!!

The total leakage is added from all sources too...spool valve, piston seal, work port valves etc....

I do not think this leakage would have any noticeable effect on performance!!

 

[wdchyd]

I think the leakage is within tolerances too!!

It is a small cylinder 2.5" bore with a 1.25" rod....and the leakage volume is the difference between the capped volume and the rod volume...as I posted before....3.68 cui per inch of CYLINDER DRIFT...

Questions:
Under what pressure was the test??
What length of cylinder drift did your test represent??

I assume about 3/4 stroke, which would be about 12" (full stroke is 15.5")....
12 by 3.68=44cui or about 723cc....sound like it is a lot, but over 20 hrs or 1200 min, it is only 0.036 cui per min or 0.60 cc per min
your test with the log would accordingly be about 1" cylinder drift in 22 minutes, which is about 0.17 cui per min or 2.74 cc per min.....

These leakage volumes is combined leakage through spool valve, piston seal, work port valves etc....

so IMO,it is NOT VERY BIG NUMBERS if pressure have been some where nearby max system pressure!!!

The total leakage is added from all sources too...spool valve, piston seal, work port valves etc....

I do not think this leakage would have any noticeable effect on performance!!

I agree, sometimes the surgery can do more harm sometimes than living with the symptoms.....BTW I may have been wrong about the Part# (not that it really matters) after closer look that seal could be a PSM-330 or PSM-330-WB....obviously the groove dim dictates which one to use...

Re: seal leakage....just monitor and document leak down rate....

wdchyd

 

[AKKAMAAN]

I think the leakage is within tolerances too!!

It is a small cylinder 2.5" bore with a 1.25" rod....and the leakage volume is the difference between the capped volume and the rod volume...as I posted before....3.68 cui per inch of CYLINDER DRIFT...

Questions:
Under what pressure was the test??
What length of cylinder drift did your test represent??

I assume about 3/4 stroke, which would be about 12" (full stroke is 15.5")....
12 by 3.68=44cui or about 723cc....sound like it is a lot, but over 20 hrs or 1200 min, it is only 0.036 cui per min or 0.60 cc per min
your test with the log would accordingly be about 1" cylinder drift in 22 minutes, which is about 0.17 cui per min or 2.74 cc per min.....

These leakage volumes is combined leakage through spool valve, piston seal, work port valves etc....

so IMO,it is NOT VERY BIG NUMBERS if pressure have been some where nearby max system pressure!!!

The total leakage is added from all sources too...spool valve, piston seal, work port valves etc....

I do not think this leakage would have any noticeable effect on performance!!

This Wolverine valve from Prince have a rated spool leakage of 3cc/min....so you with your spool valve, piston seal and work port RV, combined your numbers are actually pretty good...

 

[AKKAMAAN]

It is impossible to determine if a bad piston seal causes the drift, if you don't do the test this way.....

If cyl is hooked up this way, the test wont work...