Valve Spool, Control Valve questions

[dfkrug]

A proportional flow out put, requires a pressure compensation system.
Compensation will depend on load pressure and supply pressure, which is above what we are dealing with here I assume...

And now, I also got confused what your common definition of "feather" the valve means??

You are certainly correct that proportional control is way beyond what we
need to deal with on TBN. But definitely interesting.

Good point on "feathering". I use quotation marks because it is not a term I
have seen in technical docs on hydraulics. What I think TBN members
usually mean is that it is a partial movement of a spool valve control lever
that does not allow full flow to the work ports. Most of the discussions here
seem to involve how to use 2 different valves simultaneously with a one-
pump backhoe attachment. These are the kinds of hoes most of us have.
For me, I try to operate 2 valves right around their cutoff point, with some
(though limited) success.

 

[J_J]

Actually, feathering and proportional, is similar. By feathering a valve, you are moving the lever a certain number of degrees to produce an output to whatever, cyl, motors, etc. More lever movement the more flow you have. The feed back for this would be the visual observation of movement. I believe the definition or proportional is a linear output. There are feedback signals for proportional control to give repeatability to the movement of the valve, in response to the output. With feathering, it is operator control, but is variable between operators on the same machine, and proportional is when any operator can use the same machine and get the same results.

Wikipedia,

A proportional control system is a type of linear feedback control system.

http://www.commandcontrols.com/catalog/11.htm

 

[AKKAMAAN]

Actually, feathering and proportional, is similar. By feathering a valve, you are moving the lever a certain number of degrees to produce an output to whatever, cyl, motors, etc.

This was my immediate definition when I first heard the term "feathering"

More lever movement the more flow you have. The feed back for this would be the visual observation of movement. I believe the definition or proportional is a linear output. There are feedback signals for proportional control to give repeatability to the movement of the valve, in response to the output.

With feathering, it is operator control, but is variable between operators on the same machine, and proportional is when any operator can use the same machine and get the same results.

Can you back up this????? Links, facts....etc....

Wikipedia,

A proportional control system is a type of linear feedback control system.

Proportional Valves - Hydraulic Cartridge Valves

 

[J_J]

PROPORTIONAL CONTROL SYSTEMS

Proportional Control Theory
In the proportional control algorithm, the controller output is proportional to the error signal, which is the difference between the set point and the process variable. In other words, the output of a proportional controller is the multiplication product of the error signal and the proportional gain.

http://www.festo-didactic.com/ov3/media/customers/1100/0225252001130417097.pdf

An analogy for proportional control could be something like the fan motor in your car. With the switch set to 1, the fan will run at a certain speed, no matter who turns the switch. If it were a rheostat, then the fan speed could be different for different operators, with no set or same speed.

Proportion redirects here. Proportion may refer to:

The ratio of one quantity to another, especially the ratio of a part compared to a whole. In a mathematical context, a proportion is the statement of equality between two ratios.

 

[AKKAMAAN]

If it were a rheostat, then the fan speed could be different for different operators, with no set or same speed.

Ok that's little different than....

...proportional is when any operator can use the same machine and get the same results...

I am trying to stay on hydraulic valve operation now...

Lets move on....maybe another thread one day....when wind is blow from east to west....

 

[J_J]

Ok that's little different than....

I am trying to stay on hydraulic valve operation now...

Lets move on....maybe another thread one day....when wind is blow from east to west....

No, that was just an analogy for input to output, and no, we don't have to talk about proportional valves, because most tractors don't use them.

Go back to sleep.