Hydraulic Pump GPM Question

[kimtexn]

Hey All,

I just got a new-to-me 2004 New Holland T55DA SSS with a loader, but no rear remotes. My previous main tractor is an old Ford 540 industrial with four rear remotes. They control cylinders on both lift arms, another on the top link, and the fourth remote for hydraulic rippers on a big Gannon box blade. I've been spoiled by those rear remotes, so I want to add rear remotes plus cylinders for the 3-point arms. I realize that I don't need 4 remotes, since a cylinder on just one of the lift arms and one on the top link is enough. I could do the same thing with just 3 remotes...

I had a look at the cost of rear remote kits from Messicks. The total cost for 3 factory remote valves plus the control lever/tubing kits appears to be around $4000. I think that I can DIY it for a bit less.

So here is my question TractorData.com shows the hydraulic pump flow as 11.6 GPM, and steering flow 5.5 GPM. When selecting a spool valve, do I need one that flows at least 11.6 GPM, or is the actual maximum flow available to a valve only 11.6 - 5.5 = 6.1 GPM? In practical terms, should I look for an 8 GPM valve or one around 12 GPM?

Thanks for your help!

 

[Tx Jim]

For operating cylinders to control 3 pt functions I've suggest the lowest GPM for control valve for better infinite control of each cylinder. Power steering GPM has not bearing on operation of other hyd functions. Most newer tractors have 2 piggyback pumps with smaller gpm for steering & larger gpm pump for all other hyd functions.

Where are you located in N Central Texas? We may live close together!

 

[RickB]

Valves in an open center system have to be capable of directing 100% of the pump flow, even when no valve spool is stroked; all flow goes through each valve and back to tank. Selecting a valve with a lower rating than the pump means unwanted restrictions and heat buildup. Buy valves and hoses capable of flowing at least 12gpm.

 

[kimtexn]

For operating cylinders to control 3 pt functions I've suggest the lowest GPM for control valve for better infinite control of each cylinder. Power steering GPM has not bearing on operation of other hyd functions. Most newer tractors have 2 piggyback pumps with smaller gpm for steering & larger gpm pump for all other hyd functions.

Where are you located in N Central Texas? We may live close together!

Thanks, Jim. You are absolutely right! After I read your post, I remembered seeing a separate pump and filter for the power steering. That has to mean that the flow number for the main hydraulic pump is indeed the entire 11.6 GPM.

I updated my profile since North Central Texas is quite a big place. My place is in Clay County, TX, outside Wichita Falls. So it's really far north Texas. Hopefully we're far enough away from DFW to not be eventually swallowed up by its urban sprawl... I set up a profile several years ago, but the archives here at TBN are so vast that I've always been able to find the answers I need without resorting to posting a question. I saw many of your posts while researching the topics related to adding rear remotes. Y'all senior members here are a great resource!

Thanks again,
Kim

 

[kimtexn]

Valves in an open center system have to be capable of directing 100% of the pump flow, even when no valve spool is stroked; all flow goes through each valve and back to tank. Selecting a valve with a lower rating than the pump means unwanted restrictions and heat buildup. Buy valves and hoses capable of flowing at least 12gpm.

Thanks, Rick. I had also seen other posts in the archives that said that the valves should have the same or larger flow than the hydraulic pump. My confusion was what that value should be for my tractor. I'll be sure to look for a valve with 12 GPM or larger.
Thanks again,
Kim

 

[Tx Jim]

RickB
Is flow rating of a hyd spool valve determined by flow(GPM) that spool controls OR GPM that flows through center of valve when spool is centered in neutral position? If lower GPM spool majority of the time remained centered in neutral will that heat the oil??

If these valves in question are only randomly being utilized to change 3 pt hitch settings will that heat oil?.

Thanks, Jim

 

[BukitCase]

I agree with RickB for the most part; however, I've found that full flow on WORK ports for remotes is USUALLY intermittent, and without restrictions on things like top and tilt things tend to move TOO FAST for my liking - plus, in the above scenario using full flow hoses in WORK ports makes things more difficult to route hoses.

Exceptions to this would be things like using ONE of the valves in a multi-valve setup to run a hydraulic motor; for that, you DEFINITELY don't want any extra restrictions, or they WILL cause extra heat buildup.

All my stuff is old (like me), and my old Allis only has ONE remote; at the moment, I've added a mechanical diverter valve mounted on a fender - this lets me have top and tilt (IMO these are both MANDATORY for running a Gannon box) - but I keep finding needs/wants for MORE options (like the hydraulic rippers on the gannon, or fully articulated back blade project)

There are always more ways to do something than there is time/money to do it, but two obvious choices are either a monobloc valve

4 Spool 14 GPM Prince WVS41BBBB5C1 DA Valve | Directional Control Valves | Hydraulic Valves | Hydraulics | www.surpluscenter.com

Or the way I went (still haven't found that "tuit" I need to finish, but all the parts are waiting for me

Surplus Center

This way costs about $100 more than the first link's "monoblock" valve, BUT lets you choose EACH SECTION of the STACK TYPE valve for what YOU need, INCLUDING sections for motor control, float, etc - it ALSO lets you add just ONE SECTION at a LATER DATE, only cost being another section (around $100) and some longer thru bolts.

Another relatively inexpensive way to have full flow THROUGH the valve and still have speed control on INDIVIDUAL work ports is an adjustable flow limiter valve on whichever work ports you need to "slow down" - Again, unwanted heating won't be significant for INTERMITTENT use like positioning, and for something you'll ALWAYS want slower, you can use smaller hoses/fittings for slightly less cost and easier routing.

Lastly, if you are INSERTING the new valve stack PRIOR to the 3ph (sometimes the ONLY place that's possible) you would need the "power beyond sleeve", shown in the second link. This is important, because it keeps the backpressure (while using the 3PH) from over-pressuring the tank gallery in the new remote valve - they are usually NOT designed to take full pressure.

HTH - if you think $100 or so is a lot extra, look CAREFULLY at the Q&A section on the monoblock (first link) - it won't let you have ANY of the options that're available when you can choose EACH VALVE for YOUR uses... Steve

 

[RickB]

Valves are rated for flow through the valve. Valve ratings will determine port sizes among other characteristics. Choosing an open center valve with a lower capacity than the pump opens the door for overheating whether the valve work ports are being used or not.
TXjim has vast experience with closed center systems where valves can be sized more in accordance to the function's requirements than the pump capacity.

You can argue, debate, ignore. But the above information is factual.

 

[BukitCase]

"argue, debate, ignore" - Soooo, which are you doing Rick? Did I present anything you disagree with? If so, I'd like to know. Thanks... Steve

 

[wdchyd]

I agree with RickB about the flow rating in the valve core, but another thing to consider is the rating on the valve core is for the MAX gpm it will see. Although some remotes will only see momentary actuation, the excess return stroke displacement from a cylinder will be added to the pump flow returning back to tank, meaning total return flow should be considered to reduce the possibility of unwanted heat from pressure drop in the valve core.