Lets talk leakdown

[SpringHollow]

All of our attachments are sealed when we remove them with no pressure relief.

Ken

 

[J_J]

Hi JJ,

I heard the same thing from Terry and I have mentioned it here before. I have needle valves in line and if i lock those down, the lift arms stay.

I am not sure how other manufacturers deal with pressure relief when the circuits are closed. I suspect they just do not worry about it.

Ken

You have proved that your cyl are good

I believe you have answered your questions, and it is that your valve spools are leaking.

How much can you tolerate is what you have to answer.

You can't rebuild them, so a new valve should be in your thoughts, but only if you are worried about the lift arms falling.

Of course, if they are falling, they are leaking when you are trying to lift a load.

You can judge the leakage by looking at a hyd gage when you are lifting a large load and see if it can maintain a high pressure and not go into relief.

 

[SpringHollow]

Carl,

A couple of years ago on my PT, i would catastrophically lose lift on my loader arms and would drop the load. It ended up being the steering cylinders that needed the rebuild. They got so bad that I could not steer. When I fixed them, then the catastrophic problem with the loader went away. Life is not nearly as exciting now that I no longer have to guess when my loader will fall down.

Ken

 

[cqaigy2]

your valve spools are leaking.

I have to admit that is what i assumed the leak down was from.

 

[SpringHollow]

Again, per Terry, the valve they chose slowly leaks.

Ken

 

[J_J]

In general, you can say that about anything hyd.

However there is an acceptable leak down rate that they use to replace valves and cyl when new.

Prince engineers use 10 cc per min.

 

[ponytug]

Given the size of the cylinders, 10 cc/min would be in the range.

I can tell you that it is a higher rate if there is crud under the check valve.

All the best,

Peter

In general, you can say that about anything hyd.

However there is an acceptable leak down rate that they use to replace valves and cyl when new.

Prince engineers use 10 cc per min.

 

[woodlandfarms]

Can someone give me instructions on how to clean out my control? From a standpoint of a novice? I have no clue what a check valve us.

 

[J_J]

If you are talking about load checks, they are usually located between the work ports.

The purpose of the load checks is to prevent the cyl dropping as you shift the lever, and also to prevent fluid from flowing back into the input.

This valve from Prince is an example what a load check might look like.

http://www.princehyd.com/Portals/0/valves/LvtInstS.pdf

 

[headfirecracker]

My backhoe will leakdown sometimes within 5 to 7 sec while im trying to dig. I have checked ghe load checks and look to be good. Where do I need to loon now? I have noticed that if I put down pressure on boom and then raise it back up it will stay sometimes. Now im noticing the front bucket is trying to bypass it has more lifting power than other times I can try and lift something and say the third time itru it will lift.