Suggestion for pilot or electric motor/cylinder valve

[skidsteer.ca]

I have a saw motor running on @ 50 gpm at 2250 psi, I need to momentarily divert this flow to a double acting cylinder for a out and in cycle while the motor is allowed to coast. The motor does not need to reverse.
It would be helpful if the cylinder would auto retract after the extend stroke when switch or valve is centered, then the motor would resume under power one the retraction is complete. The valve needs to be pilot or electric over hydraulic controled.
Is this wishful thinking or not to big of a deal.
This is a open center system.

Also I need to find @ 120 feet of conveyor chain, suitable for moving a full tree towards the saw. The plan is for a 30" conveyor to feed trees to a circular saw. 2 chains loops running side by side with paddles across from chain to chain.

Suggestions?
Ken

 

[john_bud]

I guess there are several ways to do it, but I don't know enough about the downfalls of each to tell you intelligently which is the best. I do however, question a simple flow diversion to a DA cylinder. 50 gpm of flow will push a 4" cylinder 20 inches stroke in 1.3 seconds. That's way fast. You may want to use a flow divider that only allows a specific amount of flow to keep the speed down. That would also make the choice of valves easier as a 50 gpm valve is a LOT larger than a common 10 gpm or 25 gpm valve. Bigger is also more $$.

Here is a link to hydraulic calculators for speed and force (and a bunch of other stuff too)

Baum Hydraulics Corp :: Spec Calculator

 

[skidsteer.ca]

Thanks for the link and the help.

I need to get a flow tester on this machine to get some real #'s That tomorrows project. The I can narrow conveyor motor selection and valve and cylinder volumes down. Below are still estimates and it looks like 38 gpm to the saw is closer and a 4.5 by 30" cylinder would run about 6.1 seconds.

The existing machine (A 200 Serco log loader) has vickers vane, 2 pumps aprox 35 gpm and 2 more aprox 20 gpm at 1200 rpm. Desired rpm is 16 to 1800, so 52.5 gpm and 30 gpm. The power unit is mounted on the back of a rotating loader. Like a hyd excavator.

Down through the center of the swing bearing is a manifold with 15 circuits. 8 are for the 4 outriggers cylinders. (these valve are in a awkward location to operate and use loader swing pump) 4 more are for a 2 spool double acting valve, currently not used, running off the loader swing pump also, which must be interrupted to load more trees into the in feed conveyor.

Then there is one 52.5 gpm pressure and return, and a case drain.
The one 52.5 gpm to the saw has a flow divider, @ 30/70 split, with 3 electric spools valve on the split, 15.75 gpm , it now runs 3 cylinders on the slasher unit.

I'm thinking now the electric valve should run the out feed conveyor that lifts the fire wood 14' vertically over a distance of 30'. About 13.4 hyd horse power for this.
The second conveyor is bringing the tree to the saw, 16'' to 36'' at a time, then stops while the saw cuts. So I should probably use the 2 spool double acting valve in the manifold for this, as the functions don't overlap. 25.6 hyd Hp for this motor


Then I'd just need a diverter to put the saw oil to the splitter and a way to cycle it. Also to switch from a single acting motor valve to a double acting cylinder valve. Likely also some flow controls to balance the conveyor system out. But I hope to acomplish correct speed through motor selection.


Show me the holes in this line of though, beside the need to flow test. I have the mechanics worked out , just need to get a handle on the hydraulic end.
Sorry for the long post and the estimated figures.
Thanks
Ken

 

[skidsteer.ca]

Well after flow testing, here is what I ended up with running the engine at 1500 rpm ( A max of 2000 rpm is possible but would like to keep it down for better fuel economy)

Saw Motor 39 gpm at 500 psi with a 1500 psi relief setting

Electric valve 10.5 gpm at 300 psi, also 1500 psi relief.
I'd think these reliefs could be adjusted up to 2250 if needed. Though they run their present function fine. This only give me 6 hyd hp to run the conveyor taking the split wood away. Would be 9 hp at 2250 psi

2 spool 2 Way manual valve, 22 gpm at 400 psi, 21 gpm at 2000 psi. with a 2250 psi relief setting.
Twice the volume presently running the saw arm cylinder, Would provide 18.8 hp to run the tree length in feed conveyor.
Thoughts?
Ken