Hydraulic help needed

[r8f1k]

I have an old (1900-1910) hydraulic cider press. The ram comes up through the floor and presses upwards on a large frame. We pressed about 1000 lbs of apples on Saturday and I could not get the ram to hold under real pressure. It would easily push up with the pump running and then push back down once I shut the pump off. You could then hear a chatter like it was spinning the vane pump backwards and allowing fluid to head back to the tank. What do I do to get it to hold pressure? Do I need a check valve of some kind? Further enhancing the problem is that this is a single acting, gravity down, hydraulic cylinder that uses the same hose for pressure and return. Its about 10" in diameter and 38" long. I am running a Vickers vane pump and using typical hydraulic fluid. Any advice as how to get this animal working the way it should is welcomed. I should add that once upon a time, this press operated with gate valves where I think it was easier to open and close the path back to the tank. I am not using that anymore......thoughts?

 

[Zebrafive]

What are you using to control the cylinder instead of gate valves?

 

[loggin]

I have an old (1900-1910) hydraulic cider press. The ram comes up through the floor and presses upwards on a large frame. We pressed about 1000 lbs of apples on Saturday and I could not get the ram to hold under real pressure. It would easily push up with the pump running and then push back down once I shut the pump off. You could then hear a chatter like it was spinning the vane pump backwards and allowing fluid to head back to the tank. What do I do to get it to hold pressure? Do I need a check valve of some kind? Further enhancing the problem is that this is a single acting, gravity down, hydraulic cylinder that uses the same hose for pressure and return. Its about 10" in diameter and 38" long. I am running a Vickers vane pump and using typical hydraulic fluid. Any advice as how to get this animal working the way it should is welcomed. I should add that once upon a time, this press operated with gate valves where I think it was easier to open and close the path back to the tank. I am not using that anymore......thoughts?

Some pictures would help greatly!!

 

[r8f1k]

I have a few things doing the work of the valves.
1) I have a 12 volt Hydraforce selector valve which is used to drop the cylinder and close the path into the tank.

(SAE 12 15 GPM 12 Volt DC Hydraforce Selector Valve | Selector Valves | Hydraulic Valves | Hydraulics | www.surpluscenter.com)

2) I have a three phase wash down motor that spins a Vickers vane pump, which is plumbed into the above valve.

3) I use a couple ice cube relays to control the whole apparatus with a 6 button control station. UP ON/ UP OFF, JOG UP/JOG DOWN, DOWN ON/DOWN OFF.

That's it right now.

 

[oldnslo]

R8
How do you have the the Hydraforce valve plumbed? I do not see any way to make that valve work. with some addition valving.

 

[r8f1k]

Just like this:

https://www.surpluscenter.com/_MoreSpecs/I9-7986.pdf

I have it just like the instructions.

 

[oldnslo]

Which port is connect to what?

Port 1?
Port 2?
port 3?

What is the control logic or sequence of operation?

If port 1 is tank, Port 2 pump & port 3 press the only way you can lower is by spinning the pump backwards without some other form of valving in the system.

 

[ericm979]

I'd think port 1 would be connected to the pump, 2 to the cylinder and 3 to tank. So the pump would flow to the cylinder when the valve is not energized and when energized it'd go to the tank. If your pump can't hold pressure when it's not running then you'd need a check valve between the valve and pump. I'm assuming that like my apple press you crank the pressure up and then let it sit for a while for the juice to drain. You could swap 1 and 3 so you'd energize the valve to raise the cylinder and to hold it with the pump off but that'd also need a check valve, and more control logic.

 

[LouNY]

If the pump is supplying port 1, with port 2 to the cylinder, and port 3 to the tank.
When the pump is running with the valve de-energized the cylinder will receive pressure.
With the pump off the pressure would then back feed the pump and operate as described.
A check valve in the pump supply line before the valve would allow the system to hold pressure when the pump was shutoff.
The cylinder would then retract when the valve was energized.

That valve has free flow between 1 and 2 when not energized,
and free flow from 2 to 3 when energized.

If you plumb the pump to port 3 and to the cylinder to port 2 with the return to tank on port 1;
With the pump and valve energized you would apply pressure to the cylinder,
de-energizing the valve may dead head the pump and will allow flow back to the tank from the cylinder.
Again a check valve between the pump and the valve would provide the desired results I believe.

 

[r8f1k]

Let me make sure my plumbing, I'll take some shots of it tonight.