Hydraulics

Wed Oct 17, 2012 12:59 pm

Is there any thing I would have to do to hook a single acting cylinder to a 2 way control valve in order for it to work properly?

Re: Hydraulics

Wed Oct 17, 2012 5:19 pm

The answer depends on the capabilities of your control valve. The valve must be able to charge the hydraulic cylinder, hold, drain the hydraulic cylinder. And the big problem, a relief system to "unload" the pump so as not to dead head it when in the hold position.

This circuit is not often used with hydraulic rotary pumps because it will not unload the pump while holding the ram.
Industrial Fluid Power, Womack. 1996

Re: Hydraulics

Thu Oct 18, 2012 8:58 am

For a standard open center valve:

The return or "T" port goes to the tank as always, the inlet or power line is the same as always. The outlet port for the direction you want on the handle goes to the cylinder. The difference is the other unused outlet port on the valve goes to the tank similar to the return line. Separate this line from the real return line so they connect at the tank or at least far downstream. If you connect the two lines by a short line at the spool valve, the unused outlet may back feed into the return line.

When activated, the outlet goes to the cylinder and raises the cylinder, the unused outlet port would normally act to return the opposite side of the cylinder and go to the return line. You already connected to the return at the tank so the result is the same. Pull the handle to lower the cylinder, the outlet port for that cylinder then goes to the return outlet as always. The unused outlet is now activated to raise a nonexistent cylinder so it needs to go somewhere, that is why it is connected to the tank otherwise it would deadhead.

Re: Hydraulics

Thu Oct 18, 2012 5:40 pm

Thanks Eugene and Landreo.

Landreo, after reading Eugene's post earlier today I got to thinking about it and thought I would have to tee into the return. I had wondered though about the back feed problem, but didn't think about the fact that it may be less likely if connected further down stream. I would think when teeing in it would be best to run the working port straight threw and come from the side with the return port. Right? Also if I could find one, I would guess that a y would probably be better then a tee.