Leaking rod seals in Parker 2H and 3H hydraulic cylinders 2

[teleman1952]

I have been using Parker 2H and 3H cylinders for years and haven't had a problem with leaking rod seals until recently. These are the cylinders that have the "Jewel" gland with the TS-2000 primary seal and Wiperseal. On the last 2 jobs we have done, almost all of the Parker cylinders have started leaking within a short period of time. All the cylinders move at a slow speed and travel in a straight line (no arcs). The cylinders we use are:
3.25" bore x 24" stroke, MT1 mount, 30 second stroke time

4.00" bore x 8.63" stroke, MP1 mount, 35 second stroke time

10" bore x 28" net stroke, MP1 mount, 60 second stroke time, with 2" stop tube

The alignment has been checked on all cylinders, there aren't any side loads, and there are no vibrations other than slight vibrations from the running machinery. I am at a loss at finding a root cause to this problem. Parker is telling me that nothing has changed with their design. Is anybody else having problems with leaking rod seals on Parker cylinders?

 

[budt]

What do the leaking seals look like compared to seals from cylinders that run normal life?

How does Rod Surface Finish compare to cylinders that have good seal life?

Has there been any changes to the hydraulic circuit function?

Do the cylinders run longer without leaking with the replacement seals?

Are you using the same fluid as before, same brand, same company, same formulation?

As you have already determined, something has changed and finding that change should not be too difficult.


Bud Trinkel, Fluid Power Consultant
HYDRA-PNEU CONSULTING

 

[hydromech]

One thing that hasn't been mentioned is fake Parker seals.

A few years ago I ran a service centre for a Parker Hannifin distributor and as part of that we ran a quick repair service for Parker metric and imperial cylinders HMI, 2H and 3H.

There were increasing cases of rod seal glands that leaked very early after installation. After close scrutiny they turned out to be lookylikies. They looked the same but the materials were inferior and the rubber compound broke down on contact with mineral oil.

Might be worth a check...

All other suggestions I might have had have already gone.

Adrian

 

[MikeHalloran]

Did your best assembly tech just retire?



Mike Halloran
Pembroke Pines, FL, USA

 

[teleman1952]

What do the leaking seals look like compared to seals from cylinders that run normal life?

There is alot more wear than normal.

How does Rod Surface Finish compare to cylinders that have good seal life?

The rod surfaces look normal with no visible wear.

Has there been any changes to the hydraulic circuit function?

No, the hydraulic circuit function hasn't changed.

Do the cylinders run longer without leaking with the replacement seals?

So far we have changed out the seals on the 4" bore cylinders in one location about 3 times and they all last about the same length of time.


Are you using the same fluid as before, same brand, same company, same formulation?

There are two different customers involved, but both are using mineral based hydraulic fluid (Mobil DTE 20 and Union Unax AW).

As you have already determined, something has changed and finding that change should not be too difficult.

 

[teleman1952]

Quote ["One thing that hasn't been mentioned is fake Parker seals.

A few years ago I ran a service centre for a Parker Hannifin distributor and as part of that we ran a quick repair service for Parker metric and imperial cylinders HMI, 2H and 3H.

There were increasing cases of rod seal glands that leaked very early after installation. After close scrutiny they turned out to be lookylikies. They looked the same but the materials were inferior and the rubber compound broke down on contact with mineral oil.

Might be worth a check...

All other suggestions I might have had have already gone."]Quote

Thanks for the information. We are seriously looking at having the seals tested at a lab.

 

[MikeHalloran]

I'd send a sample of the customers' fluid to Mobil and ask them if it's actually their stuff.



Mike Halloran
Pembroke Pines, FL, USA

 

[hydtools]

If the seals are wearing out faster then look at the wiper, wiper gland and at the seal gland.
If the wiper is doing its job too well the rod is retracted very dry and there is not enough lubricaton for the seal. If the wiper is not doing its job well enough then grit is entering and wearing the seal lip.
If the seal gland is undersized then the seal squeeze is too tight causing excess load on the seal lip. The seal will run dry.

If the rods are chrome plated they may not have been post-plate finished and the surface may be 'toothy'. Chrome plate does not lay flat like nickel plate, as plated.

Ted

 

[maytag]

I had a similar situation with the Parker cylinders-found that the seal amterial was not compatible with the water glycol.

Tom