Hydraulics. Spool valves, Directional Control Valve. Help!!! please.

[jordhandson]

I am working on a project at the moment so lets see if I can write this so you understand.

I have at the moment a 1 lever valve, its fed by ¾” flow and return pipes. I need 2 more levers. I have been looking for a 3 lever valve, they are about at my budget, but the sellers either to far away, wont post, or don't even reply.

I can purchase a 2 lever spool valve new on the fleebay for 51 pounds.

My question is, If I mounted the 2 lever next to the single lever valve and tee’d off the 3/4” flow and return pipe would it work.??

 

[8ob]

My question is, If I mounted the 2 lever next to the single lever valve and tee’d off the 3/4” flow and return pipe would it work.??

No.

Edit, you can run them in series but you would only be able to use one lever at a time.

Bob

 

[frank horton]

have a look at a tractor breakers...spool valves, always loads'a about.....
altho new is nice.....

 

[Jan-DIY]

I would buy a 2 section valve and install it upstream the existing one. But it must be a “pressure through” valve. In general you can not take the pressure from T port.

 

[m_c]

The key question, is the existing valve open or closed centre?

If this is on something old/budget, it'll likely be open centre (basically means that with the lever in neutral, oil flows from the P(ressure) to T(ank)/R(eturn) and the oil pressure remains low until the spool is operated).
Unless the existing spool has a pressure carryover port, then you'd have to install the new valve before the existing valve, and ensure it has a pressure carry over port.

If it's on something newer with better hydraulics, it might be closed centre (there is no oil flow through the valve, and the input pressure is maintained at full pump pressure when no spool is actuated). In which case you can simply T-in a new closed centre spool to the pressure line.

 

[Jan-DIY]

Never seen a closed center without LS control in a standard configuration because you need to have full pressure upstream without sensing. This will generate much loss when using a fixed displacement without pressure accumulation.

 

[Rannsachair]

Would be easier to answer with a circuit diagram or even just the model of pump and existing valve. As said above there are different types of hydraulic circuits: open centre, closed centre, load sensing, so easy to get it wrong or get the wrong advice.

 

[dieselsamurai]

I am working on a project at the moment so lets see if I can write this so you understand.

I have at the moment a 1 lever valve, its fed by ¾” flow and return pipes. I need 2 more levers. I have been looking for a 3 lever valve, they are about at my budget, but the sellers either to far away, wont post, or don't even reply.

I can purchase a 2 lever spool valve new on the fleebay for 51 pounds.

My question is, If I mounted the 2 lever next to the single lever valve and tee’d off the 3/4” flow and return pipe would it work.??

If the spool block has a N port that is for a "Power Beyond Adapter" that allows you to do what you want , I have used this on my mini digger when I converted it from closed to open hydraulics. I have two spool blocks that are in series using this and they operate as one i can use a valve on each one at the same time with no issues

 

[jordhandson]

No.

Edit, you can run them in series but you would only be able to use one lever at a time.

Bob

Cheers Bob. This sounds like I can do it only using one lever at a time is ok

 

[jordhandson]

Bob when you say "run them in series" do you mean flow from the tractor in to the first valve, out the first valve, then into the second valve, then out from the second valve back to the tractor. sorry if that sounds a bit thick

 

[jordhandson]

The key question, is the existing valve open or closed centre?

If this is on something old/budget, it'll likely be open centre (basically means that with the lever in neutral, oil flows from the P(ressure) to T(ank)/R(eturn) and the oil pressure remains low until the spool is operated).
Unless the existing spool has a pressure carryover port, then you'd have to install the new valve before the existing valve, and ensure it has a pressure carry over port.

If it's on something newer with better hydraulics, it might be closed centre (there is no oil flow through the valve, and the input pressure is maintained at full pump pressure when no spool is actuated). In which case you can simply T-in a new closed centre spool to the pressure line.

the valve I have at present is open centre, ie oil flows from the tractor straight back to the tractor until I pull the valve lever

 

[jordhandson]

Better put a bit more info, I am building, rephrase that, I have built father a tractor mounted post driver or knocker, it works a treat but father has asked me to make it so he can have side to side tilt and front to rear tilt off the top link, to save him winding it the get the levels spot on. I have the extra 2 rams just need to sort out the controls.

Thanks for all the advice
Jord

 

[8ob]

Bob when you say "run them in series" do you mean flow from the tractor in to the first valve, out the first valve, then into the second valve, then out from the second valve back to the tractor. sorry if that sounds a bit thick

Thats the one, I have done this on a few bits of plant. Just need to make sure the pressure reliefs on both spool valves are set the same.

Bob

 

[m_c]

For a post knocker, I would advise building a block from slices, not a monoblock valve.
That way you can get a single acting slice for the weight, double acting for the tilt/slide, and when the weight slice inevitably wears out, you just need to replace the single slice.

 

[jordhandson]

For a post knocker, I would advise building a block from slices, not a monoblock valve.
That way you can get a single acting slice for the weight, double acting for the tilt/slide, and when the weight slice inevitably wears out, you just need to replace the single slice.

that is a good idea i think his David brown has slice, the valve I have on it at present is a double acting valve but Im using it single via the connections