I have to extend and retract a cylinder (and i must be able to control it) with out the use of a DVC this can be done using 1, 2 or 4 componants. i was just wondering if someone could give me an opinion on whether or not the circuit i have come up with will work or if i am on the right track. i am not the best at hydraulics.Forged Steel Valves  (*note: a vertical cylinder may be used instead of the horizontal).

500psi system pressure (the pump has a relief valve already incorperated) goes to both ends of the cylinder (horizontal with no load on it). the blank end will have a T on it also going to a neelde valve which then goes to the tank.
when the needle valve is closed(no flow going though) the pressure will build up on both sides of the cyclinder. because of the area on the blank end, the fluid will be pushed out from the rod end and back to the blank end (causing regeneration).Needle Valves the cylider extends.
when the needle vavle is opened, the fluid on the blank end will travel back to tank and the pressure will build up on the rod end.Filter this should cause the cylinder to retract.

Take the circuit you dreamed up and put a second needle valve in between the tee you have with the needle valve going to tank and the tee with the line from the rod end.

Closing the tee to tank and opening the other tee extends regeneration.

Oprning the tee to tank and closing the other one will power retract the cylinder.

With 4 needle valves you can make it double acting with full force both ways.Bellow Seal Valve

Heck of a class assignment. What is the class title.

A few things that might help an electrical person:

Pumps don't make pressure only FLOW

Pressure only happens when there is resistance to flow

Hydraulics & Pneumatics (Fluid Power) defines Normally Closed (NC) as a blocked or no flow situation and Normally Open (NO) as a path for flow or a hole.

As you can see it is exactly reverse of electrical since electrical is defining the Contacts of a Switch. So, when I am discussing Fluid Power with electrical types I use Normally Passing and Normally Non-Passing to keep everyone on the same wave length.Water Pump Control Valves

Voltage is the same as Pressure (PSI) in Fluid Power and Current (amps) is equal to Flow (GPM)in Fluid Power.

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