Example of cavition damage

   / Example of cavition damage #1  

oldnslo

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Branson 2400H, JD X540
The attached picture is an example of what happens to HST when they are run low on oil or started and operated on cold mornings I.e. growling at you. This pump came of a test stand where I work. This is not an oil cleanliness issue since we test all of our stands on a monthly basis.

Roy
 

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   / Example of cavition damage #2  
The attached picture is an example of what happens to HST when they are run low on oil or started and operated on cold mornings I.e. growling at you. This pump came of a test stand where I work. This is not an oil cleanliness issue since we test all of our stands on a monthly basis.

Roy

Roy, What kind of machine did that come out of? What kind of Hyd fluid was used? How many hours? Thanks for the example a picture is worth is a thousand words.
 
   / Example of cavition damage
  • Thread Starter
#4  
This is used on one of out test stands that we use to test valves we build. runs between 500 & 3,500 PSI depending on valves we are testing at the time.

It is from a Vickers PVB 10 pump. Oil is ISO 32 operating between ambient of 68 degrees to max of 110 degrees. What killed this pump is start-ups with the max volume stop set at flows around 2 - 3 GPM. This pump sits on top of the reservoir so it has to lift oil around 12 - 15" inches. Inlet hose is 1 1/4" so ther is potentially a column of air 12-15" long by 1 1/4" diameter.

Pump sounds like a rock crusher when they start it up. Been trying for years to train people not to do this but it hard to teach old dogs new tricks...

Roy
 
   / Example of cavition damage #5  
I've seen a lot of failures in axial piston pumps but nothing like that. I've never seen slippers looking like that.
 
   / Example of cavition damage #6  
This is an instance where a picture is worth way more than a thousand words! Most people won't believe the damage cavitation causes if you explain it to them and think you are "full of it".

oldnslo, your pics may save many people a great deal of high dollar grief. :thumbsup::thumbsup::thumbsup::thumbsup:
 
   / Example of cavition damage #7  
I would say that most people that own any hydraulic equipment do not know what cavitation is or what it sounds like.

A simplified answer, is that cavitation is developed when the vapor barrier of the liquid is broken and bubbles form, and when the fluid moves to a pressurized area, they will burst with high energy, and if done for a while, then it can erode metal to the point of destruction. While in the Navy, I listened to ships cavitation, and if you know anything about cavitation, in reference to ships propellers, that when something is cavitating, any rpm above that will not produce any gain, otherwise, you lose efficiency. If you look at some of the old ships propellers, you can see the effect of cavitation.
 
   / Example of cavition damage #8  
I work in a relatively large hydroelectric station and I've seen cavitation eat right through 2.5 to 3.0 inch thick steel turbine runner blades, pretty awesome to see the incredible damage that air bubbles can do.
 
   / Example of cavition damage #9  
Any reason you don't design the test stand with a flooded suction I think it would help?

Were I use to work we had the same issue with some vickers pumps and tank assy but they also had a restricted inlet 2" down to 1 1/2 we changed the inlet and still had problems.
I built a prototype out of a truck bed fuel tank motor/pump on the lower part of the L and we didn't have any more problems.
We went back and relocated the pumps on the original tanks to the floor to fix them.

tom
 
   / Example of cavition damage
  • Thread Starter
#10  
Any reason you don't design the test stand with a flooded suction I think it would help?

Were I use to work we had the same issue with some vickers pumps and tank assy but they also had a restricted inlet 2" down to 1 1/2 we changed the inlet and still had problems.
I built a prototype out of a truck bed fuel tank motor/pump on the lower part of the L and we didn't have any more problems.
We went back and relocated the pumps on the original tanks to the floor to fix them.

tom

Yes, the reason is we don't have time or money to properly repair and solve this problem, we just have to to fix it when broke. Please don't get me started on this since i suspect anyone that has worked in a factory has run across this problem.
 

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