Valve Spool, Control Valve questions

[/pine]

I too am learning about applied tractor hydraulics and one of the first things to consider when choosing a valve is its center action...most valves are either open or closed "center"...

"closed center" valves leave the cylinder(s) in position when the valve is released i.e., leaving pressure on the line...

"open cneter" valves neutralizes the pressure when the handle is released and returns to center...

 

[woodlandfarms]

Hey JJ. Well... Help me out here a bit...

What I have on the PT is a valve block that is (I believe) a 3 valve open center. Valve 1 and 2 operate lift tilt and dump and are manipulated by the handle on the left. The 3rd circuit is for the Quick attach lock, that can also be uncoupled to operate various hydraulic implements (for me it is the grapple which I use extensively and the backhoe for the moment).

I do not know who manufactures the valve block. PT is notorious for removing part numbers.

My idea was to tie into this valve block (can I, you scared me with your idea) and run a line to this new control on the left side of the PT and then run the return back to the existing valve block or wherever it dumps to.

I am sure I am making this way to simple and the process is much more complicated than I have imagined. Typical of me.... Oh here are some pix...

The first two are of the valve body, the third is of the control, and the 4th is the general area of the proposed new control... May have to weld a plate on.

 

[kennyd]

I too am learning about applied tractor hydraulics and one of the first things to consider when choosing a valve is its center action...most valves are either open or closed "center"...

"closed center" valves leave the cylinder(s) in position when the valve is released i.e., leaving pressure on the line...

"open cneter" valves neutralizes the pressure when the handle is released and returns to center...

Not quite. Actually not at all! OC and CC has to do with the "center" of the valve-where the fluid from the pump flows when the valve is in neutral.

Both OC and CC valves can/will leave the cylinders in postion when the handle is in neutral. The proper valve we usually need for our machine is actually called a "tandem center" valve, but the Surplus Center uses this interchangeably with "Open Center". In most of the industry "Open Center" means the work ports are open to the center like a motor spool valve. In "Tandem Center" valves the work ports are block so the cylinder stays put.

 

[AKKAMAAN]

I know AKKAMAAN must have a drawing on this. He must be sleeping today.

Sorry guys...I'msjust reading your posts....I have spent day in Victoria BC, and I will see what I can come up with in sunday am.....

I so "sorry" I failed on you guys.. ...LOL....

 

[J_J]

Hey JJ. Well... Help me out here a bit...

What I have on the PT is a valve block that is (I believe) a 3 valve open center. Valve 1 and 2 operate lift tilt and dump and are manipulated by the handle on the left. The 3rd circuit is for the Quick attach lock, that can also be uncoupled to operate various hydraulic implements (for me it is the grapple which I use extensively and the backhoe for the moment).

I do not know who manufactures the valve block. PT is notorious for removing part numbers.

My idea was to tie into this valve block (can I, you scared me with your idea) and run a line to this new control on the left side of the PT and then run the return back to the existing valve block or wherever it dumps to.

I am sure I am making this way to simple and the process is much more complicated than I have imagined. Typical of me.... Oh here are some pix...

The first two are of the valve body, the third is of the control, and the 4th is the general area of the proposed new control... May have to weld a plate on.

Carl.

That setup is very similar to mine. It is a manual circuit, and you are probably using it with the grapple. I don't have the manual, or never looked at mine to see if it had PB. If it did, it would be simple to add an electric valve. Seems like I posted awhile back about getting a new joystick with PB, and using the old one on the left side.

 

[woodlandfarms]

Thanks JJ. You did indeed. I am a little leary of the electric control as I do not want any wires dangling around as I tend to rip them off in the brush and trees.

OK. This all said. What exactly is power beyond? I assume it is a port generally closed on a valve spool that you can open attach a hose to and let the juices flow to a new control or whatever... Any special rules for Power Beyond (how to run, cap and return?)

 

[/pine]

Not quite. Actually not at all! OC and CC has to do with the "center" of the valve-where the fluid from the pump flows when the valve is in neutral.

OK, Thanks for straightening me out...I've been reading so much...not sure where I had gotten the wrong idea about open and closed center...
found this:
https://www.surpluscenter.com/techhelp.asp?UID=1960011623184079&catname=


Thanks again...

 

[AKKAMAAN]

I have a very basic question to ask. What is the difference between various valve spool controls. I am looking to add another remote, and there appears to be 4 different types (or at least they are labeled that way).

Log Splitter Valve
Motor Spool Valve
Control Valve (the most common)
Electric control valve

Log Splitter valves seem to be the cheapest, and motor spools the most expensive.

I get what electric is (although I have a question, can you "feather" an electric valve - meaning slowly let the juice flow for precision work or is it just on and off)

Can anyone help a layman get through these vageries?

Thanks

Here is my 2 cents.....for now....lol

The valve an operator uses to control an actuator (cylinder or motor), is a control valve, directional control valve etc....many names on the same thing....all these valves you are mentioning are control valves.....

A log splitter valve is a control valve, often with some extra features like auto cycle and/or detent. log splitter valves are hand operated, and they direct a flow, that is "proportional" to how much you move the spool.....

The opposite to a proportional valve is an "on-off" valve, in which the spool only can take two positions, either neutral or fully "open" work port. Most electric solenoid valves you see on equipment is "on-off"- control valves. You operate them with an electric switch, or they are operated automatically by a electric control system.

There are proportional electric valves, the are controlled by an electric amperage, that is proportional to an operator "signal" or electric lever movement (joystick). This amperage, is usually created by a PLC (Programmable Logic Controller ) unit that sends out a PWM (Pulse Width Modulated) amperage to the electric solenoid (especially designed for proportional control valves). These Proportional hydraulic control valves are expensive.

All hydraulic control valves can be set up for different characteristics. This is made by different spool design. Usually the valve housing is the same and the spool design varies with type of system to work in, like an Open Center system, Closed center system, Load Sensing system etc. Even different type of actuator setup requires different spool design, like motor spool, regenerative spool, 3 way spool for single acting cylinder , 4 position spool with float etc etc. There are also variations in how spools overlap the ports when opening and closing for flow. All these things combined makes it possible to have hundreds of different spools for different purposes. And they all can be fit in the same housing, together with some extra control accessories, like power beyond plugs, and detent controls etc.

A motor spool valve has its special feature in neutral position. If we go back to a regular spool for a double acting actuator (cylinder), that spool keeps both work ports closed in neutral. The actuator can not move when valve is in neutral. Many hydraulic motor applications require the motor to be "unlocked" when control valve is in neutral. A hydraulic wire winch is an example, it will need a spool for bi directional motor control, but with valve in neutral, we might want to be able to pull out the wire by hand, or roll it back on to the drum by hand. Then the motor have to be "unlocked" in neutral. That is made by using a "motor spool" in the valve. With a one directional motor this can be solved with a check valve between the two work ports.
Such check valve is also used to let a motor, with inertia on the shaft, slow down by it self when control valve, suddenly, is in put into neutral. Other wise this rotating inertia will create a "pressure pump" of the motor, and oil wont have any where to go. An example could be a large diameter, heavy mass, circular saw.

The reason a log splitter valve is cheapest, is that it is a "low quality" control valve. You do not put a 1500$ control valve on a 1000$ log splitter......

As I explained above, you need some advanced electronic to "feather" an electric control valve. You also need a especially designed electric control valve for this. So don't expect a regular on-off solenoid valve be "feathered" by changing supply voltage. It takes a little more than that.

This Prince Serie 20 valve pdf file shows how a system of spools are used in one housing depending on valve purpose...page V6....have fun...

 

[J_J]

Carl, In order to operate the PT and keep the left hand on the steering, and the other hand on the joystick valve, the best way to operate a grapple circuit is with a solenoid valve to swatch circuits between the QA cylinder, and the grapple circuit. To use the grapple as you have it now, you must remove your hand off the joystick and reach under the dash and operate the QA/grapple circuit, or move the QA lever with the left hand. The most convenient way to do what you want to do is to install a new joystick valve with PB, and a solenoid hyd valve to operate the grapple. If you need to feather a valve, and want 12 v activation, then you need a proportional valve, but they ain't cheap.

If I were to upgrade the valves on my PT, I would do as above, and use a joystick valve with PB, and a solenoid valve to operate the grapple, with a needle valve in-line to adj flow..

Keep in mind that the lift, tilt, grapple circuit is downstream of the steering valve, and uses the fluid flow that the steering cyl are not using.

If you were to add a small hyd pump, fan-belt driven, and a small log splitter valve for the grapple circuit, that would give you another independent hyd circuit.

All the hyd on the front of my PT-1445, uses a pump like this mounted like I said, and does a fine job with the hydraulics. The pump only pumps about 3 GPM.

PB, Power Beyond allows you to add valves downstream of the first valve. Which ever valve is activated, the valves downstream will get nothing, or the remainder of the fluid the operating valve is not using. Each valve with PB must return cyl/motor fluid out the tank port.

 

[J_J]

Carl,

As mentioned in anther post, the diverter valve will let you use the joystick to operate the grapple, by switching the fluid from the tilt cyl to the grapple cyl, and all this done using one hand, with a switch on the handle to switch circuits.

Wiring is no problem as you bundle and tuck the wiring out of the way under dash.