L 4740 hydraulics question

[Timan]

Does anyone have any information or experience with boosting up the hydraulic system a little on a Grand L4740? I have already raised the pressure relief valve to within the maximum specs but would still like just a bit more flow and pressure. Possibly a larger pump available?

 

[KennyV]

There is no practical way to use a larger pump in the tractor...
What are you trying to operate?.. Is it something you could use an external PTO driven pump to accomplish?? KennyV

 

[Timan]

Trying to get a little better performance from the loader and backhoe. I can use a pto pump for the backhoe but I would rather beef up the pump on the tractor if possible. The backhoe uses the tractor hydraulics now.

 

[J_J]

You already have this.

HYDRAULICS

Standard Pump Flow Implement: 9.8 gpm

Power Steering: 4.9 gpm

Maximum Pump Flow 14.7 gpm

You might be able to combine the two flows into one for specific operations.

This way would not cost so much, where as the PTO pump will cost about $500.

An electric valve could switch or merge the flows for BH work, or switch back for steering.

It is hard to believe your BH is not performing well at 9.8 GPM.

You probably have some hyd restrictors in some of the BH circuits.

Hyd flow is what gives you the speed of operation. Pressure provides the force.

 

[Timan]

Thanks J J for the input. I will check to see if there are any restrictions. The specs for the hoe (Woods BH-90X) show 9gpm the lowest flow necessary for operation. I can test pressures but I have no way to test flows. Anyone know of a source for inexpensive flow meters?
Also, I didnt know it was possible to combine the flows together. I am going to look into that.

 

[KennyV]

...I have no way to test flows. Anyone know of a source for inexpensive flow meters?

Check what kind of flow you have with the supply hose running open into a 5 gallon pail
... how many seconds will it take to fill the pail?

Are you able to operate your BH at full engine operating rpm? most do not, and run the engines at lower rpm just to 'reduce' gallons per min flow rates... KennyV

 

[Timan]

kennyV
does it matter which supply hose I use to test flow? I have the circuit for the backhoe, the loader circuits and 2 rear circuits.

 

[J_J]

Thanks J J for the input. I will check to see if there are any restrictions. The specs for the hoe (Woods BH-90X) show 9gpm the lowest flow necessary for operation. I can test pressures but I have no way to test flows. Anyone know of a source for inexpensive flow meters?
Also, I didnt know it was possible to combine the flows together. I am going to look into that.

With a flow of 9 GPM, your flow test should produce about 3 gal per 20 sec. Or 1 gal for 6.6 sec.

 

[J_J]

This hyd tester would really be nice to have, but at $3795.

Flo-Check USB Hydraulic System Analyzer

 

[KennyV]

kennyV
does it matter which supply hose I use to test flow? I have the circuit for the backhoe, the loader circuits and 2 rear circuits.

Really will not make much difference as you will be free flowing... they all should have about the same open flow... KennyV

 

[Timan]

KennyV
Why do you say there is no practical way to install a bigger pump? Just Curious.

 

[J_J]

To check flow to a cyl on the BH, remove the hose from a cyl and place in a bucket. Run the engine at max rpm, and determine flow.

1.17 gal in 7 sec = 9.8 GPM

This may help you determine if you have restrictors in the BH hyd system.

9.8 GPM should be more than enough to operate the BH

As far as a larger pump, the volume your tractor is producing now takes about 25 HP.

If you could find an exact match and have the room,
you could add a larger pump.

You have enough total HP to pump about 24 GPM's at 2500 psi, with no HP left to do work.

What is the GPM rating on your BH?

 

[KennyV]

A J J said... and if you have unlimited $$ for trying to make a larger pump work in your tractor... Just seems impractical to me... a self contained PTO pump externally mounted would be quicker, handier & a lot cheaper .. KennyV

 

[J_J]

Another negative on the PTO pump other than price, is the pressure . 2250 psi, is lower than the tractor hydraulics.

However if you want fast hydraulics, use large GPM PTO pump, a two stage hyd pump, or a fast extend valve.

 

[Timan]

My backhoe needs 14 gpm at 2500 psi to be at peak performance.
Do you know if Kubota manufactures there own pumps? The control valves they use are Husco I believe.

 

[J_J]

I would think Kubota would offer a larger pump for BH option.