14 replies to this topic

[Nytractorguy]

I'm building a tractor and want to add a second hydraulic valve. I have 3 spare single spool valves and want to put one on the back of the tractor. I have to run new lines anyways. Could I add a tee after the pump and run to each valve or do I need to go thru one to the other and back to the pump?

[Nytractorguy]

This is on a garden tractor BTW

[secondtry]

There are many different configurations of valves. Until you know exactly what valves you have you or we are only guessing. If one valve is now working properly in the circuit I know of no way that installing a T after the pump would work. You have to start thinking in the terms of pressure and return lines.  Most times the hydraulic control valves for hydraulic lift on a garden tractor are two way open center spring loaded which means you push to operate the cylinder in one direction and pull for the other direction. When you release the valve it returns to center and the cylinder is locked in its present position and the hydraulic flow is routed directly back to the return to tank line to relieve the pressure of the pump. In this position with the valve in the center position there would be no pressure available  at your proposed T. Adding a second Identical valve by using a T in the pressure line would add a second open center relief to return and make sure nothing could work properly. I have a book ISBN number 935100-B. Industrial Hydraulics Manual. It explains all the standard valves and circuits in hydraulic systems. The people who have done hydraulics for years can often identify the different valves, circuits, and systems by sight but for a dummy like me it takes a lot of studying.

   I still haven't gotten the hydraulic system on my JD 317 figured out. It has two control valves and a diverter valve controlling lift cylinder and front two front hydraulic ports which I have actuating lift and angle cylinders on a front blade. When operating the blade I sometimes get cross talk between the cylinders. 

   Don.

[GardnMastr]

Second try has given you correct information. Open center hydraulics go in a daisy chain or serial fashion. The outlet (or return to sump) of the first valve would be the inlet of a second valve. Its outlet would need to return to sump (reservoir). The first valve’s relief should be the highest, each valve downstream should each have a relief setting just a little lower. Second try, I bet your “crosstalk” happens when a cylinder bottoms out on its stroke. Back pressure can do funny things. Any time the oil goes over the high relief, the oil is directed back to sump, and all the other functions stop.

[Nytractorguy]

Now that I think about it daisy chaining them does make sense. I don't know how to add pictures to my reply but i am using the cub cadet control valves.

[29 Chev]

 I don't know how to add pictures to my reply but i am using the cub cadet control valves.

This should help explain how to load pictures

https://gardentracto...file-uploading/

[secondtry]

 Second try, I bet your “crosstalk” happens when a cylinder bottoms out on its stroke. Back pressure can do funny things.

   Have not investigated yet. At times when lowering the blade it contacts the ground and begins to change angle. I suppose the pressure goes up slightly when the blade makes contact. Always turns the blade to the right.

   Don
 

[Nytractorguy]

This is the valve I am using.

Attached Thumbnails

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Edited by Nytractorguy, January 14, 2021 - 02:35 PM.

[secondtry]

This is the valve I am using.

Has an actuator shaft on the left end. Push and  pull on that shaft to see if it is self centering (spring loaded). Looks like the ports on the right end are for pressure and return. The A and B ports would go to the cylinder. Could be open center or closed center. If open center flow between the two ports on the right end should be free with the control being in the center position. Could also have a float position where there is an open flow between A and B ports. If you google the manufacturer and numbers you might be able to deturmin exactly what you have. Some valves can be set up for power beyond and some not. I have seen systems where  an open center valve was wired into one position or the other to effectively bottom out the cylinder  it controlled which forced the to go to the other valve. I am not capable of identifying a valve by sight and as far as I know valves that externally  look identical except for the numbers  can be greatly different in function and some can be reconfigured for different options. Again I suggest a trip to the library.

Don 

[secondtry]

Found this in a quick google search. I know nothing about it and did not download it. It appears to be a digital copy of the book I have. 

  https://5a.avtomir21.ru/15.html

Don

[KennyP]

This is the valve I am using.

I plan to use that same valve on my Sears project!

[KennyP]

Found this in a quick google search. I know nothing about it and did not download it. It appears to be a digital copy of the book I have. 

  https://5a.avtomir21.ru/15.html

Don

That link never opened!

[secondtry]

That link never opened!

Don't open for me either. How I got there is google ISBN number 935100-B' go to the second page of the results, open the second item on that page. I just went back there and clicked download. It said I had to sign up and be a member. already having the book I didn't bother.

Don

[secondtry]

Found what appears to be the same book but 4th edition on amazon relatively affordable. It may  be available at the library. The name is Vickers  Industrial Hydraulics Manual 

   Don

[Nytractorguy]

Has an actuator shaft on the left end. Push and pull on that shaft to see if it is self centering (spring loaded). Looks like the ports on the right end are for pressure and return. The A and B ports would go to the cylinder. Could be open center or closed center. If open center flow between the two ports on the right end should be free with the control being in the center position. Could also have a float position where there is an open flow between A and B ports. If you google the manufacturer and numbers you might be able to deturmin exactly what you have. Some valves can be set up for power beyond and some not. I have seen systems where an open center valve was wired into one position or the other to effectively bottom out the cylinder it controlled which forced the to go to the other valve. I am not capable of identifying a valve by sight and as far as I know valves that externally look identical except for the numbers can be greatly different in function and some can be reconfigured for different options. Again I suggest a trip to the library.
Don

I do have one of these already on a tractor amd they return to center with no float. I blew thru one and it looks to be open in the center position for the inlet and outlet so look like daisy chaining is the way to go.

Edited by Nytractorguy, January 15, 2021 - 05:07 AM.