Open center Closed center?

   / Open center Closed center? #31  
J_J again thanks for your patience with me and these 'basic' questions. Believe me I've asked around here but obviously not the right ones or possibly I'm not too clear in what I want. Anyway I'm going to really study your # 27 post to FULLY get it into my head what to do. (any comments on the picture link would be appreciated, pos or neg, I just want to see if I'm on the right track)

hydroholic
sandbar w/fl
 
   / Open center Closed center? #32  
The need for the higher GPM valve is to prevent thermal breakdown of the hydraulic oil due to excessive friction when using the valves. I have a 301a with prince sv series valves that get so hot when using them that you will get 2nd degree burns if you touched them after 30-45min of moderate use. The pump will try to force all of its flow through the valves if no other functions are continually being used.
 
   / Open center Closed center? #33  
medic0648,

You only need to match pump GPM and valve flow.

Bigger is not always better.

An open center hyd system, the pump fluid is always flowing but at low or no pressure .

A closed center hyd system may have standby pressure at the valve , but no flow.

You should not be getting that much heat if there is no restrictions.

Put a hyd gage in the system and with all valve in neutral, tell us what you read.

Maybe a flow and pressure test is necessary on your tractor.
 
   / Open center Closed center? #34  
0psi on output with valves closed. Pump puts out 23gpm. The stated GPM on tractor data is incorrect. It's OK if I don't use the loader much.
 
   / Open center Closed center? #35  
The factory loader valve was a Cessna rated for 50+gpm
 
   / Open center Closed center? #36  
The need for the higher GPM valve is to prevent thermal breakdown of the hydraulic oil due to excessive friction when using the valves. I have a 301a with prince sv series valves that get so hot when using them that you will get 2nd degree burns if you touched them after 30-45min of moderate use. The pump will try to force all of its flow through the valves if no other functions are continually being used.

I understand the principles of closed center systems and respectfully disagree.
More than likely you have an unrelated internal high pressure leak that is causing the heat problem. Intermittent use of an undersized single spool valve isn't going to cause that much heat. It could be a 2 GPM valve and when not in use it may as well be a pipe plug. The user isn't likely to send the cylinder lock-to-lock at full speed anyway. Feathering the spool reduces its capacity.
 
   / Open center Closed center? #37  
Notice I said it's OK when not being used. But under moderate use it gets hot.
 
   / Open center Closed center? #38  
OK, this is the way I had the grapple hook installed when my troubles BEGAN.
Break into the bucket/loader valve and insert grapple hook valve and cylinder (in series).
With grapple hook in neutral bucket/loader works as advertised.
Depressing either open or closed on the grappling hook STOPS the bucket/loader operation and the grapple never works. Releasing the grapple back to neutral restores the operation. I feel sure now that the grapple hook valve is of the OPEN CENTER type.

My next move will to convert (or buy) the valve necessary (closed center) and try it again. This time I will put 'T's' in the loader/bucket lines and run the grapple (closed center) hook in that fashion. If that does not work I'm considering installing a large thermal nuclear device and testing it on the back 4 acres. Works for me.

hydroholic
sandbar w/fl
 
   / Open center Closed center? #39  
Since your tractor is closed center, all valves should be in parrallel, and that means that the same line feeds all valves IN ports.

You don't need to break into the bucket lines for anything.

When you release the lever on a closed center valve, fluid from that valve stops flowing.
 
   / Open center Closed center? #40  
I think I understand you now J_J, i.e. don't break into the "bucket lines" but I will 'T' off the "IN" and "OUT" feeds to the bucket/loader valve and "PARALLEL" my new "CLOSED CENTER" valve to my grapple cylinder.

OK, let me try this and I'll get back to you guys with pictures and a "successful" sigh of "oh, yeah".

hydroholic
sandbar w/fl
 
 
Top