Two hyd pumps feeding a splitter cylinder?

[rancher2]

I have a 6.25 inch cylinder with a 3.50 rod on a to be firewood processor. The cylinder has two 16 SAE ports for extend and two for retract. I am running two motors on the processor a 20 hp with a 28 GPM two stage with a auto cycle valve. It is taking 20 seconds to cycle the cylinder 26 inches. The other motor is a 40 hp and is running two hyd pumps a 20 for the saw, live deck and a 7 for saw cylinder, clamp, wedge adjust. Question is if I mount another pump on the front of the 40 hp motor to speed up the cylinder cycle time will the two work with each other. I would probably disengage the second pump when the pressure starts building as the second pump will have to be a single stage as it must be ccw drive. Has anyone used two pumps to feed there cylinder.

 

[muddstopper]

First a question, and then maybe a suggestion, Is your valve that you are using to run the saw motor power beyond capable. If it is, then this is my suggestion. Provided the saw valve is power beyond capable, you can use the power beyond to tee into the inlet side of you spliter valve to provide extra flow to the splitter circuit. You need to install a check valve between the saw CV and the splitter CV to prevent back pressure, and you could install a unloader valve between the check vavle and the splitter valve to allow the circuit to act like a two stage pump. Where as when the slitter isnt seeeing high pressure the oil from the saw circuit would pump thru the splitter circuit increasing splitting speed, but when pressure reaches a set amount, the unloader vavle would dump the saw circuit back to tank. When neither circuit is being used both the saw circuit and the splitter circuit would dump back to tank thru the splitter control valve. With this method, you could mostly use what you already have and only need to purchase a unloader valve and a check valve and what ever hoses and fitting needed to hook it up. Now doing things this way would mean that if your saw is running, there wouldnt be any extra fluid to speed up the splitter, but as soon as you stop sawing, you would see a very noticeable increase in splitting speed. I suspect that after a round is dropped in the splitting trough, that the saw isnt running while you are splitting and advanceing another log to be sawn so this is just fluid that isnt being used. this method wont effect the way the saw runs at all and will allow you to use the extra fluid from the saw while it is setting idle.

 

[rancher2]

Mud Thanks for the reply. I had considered using the saw pump. Problem is there are two hyd tanks on this set up and the splitter oil and the saw oil are separate tanks. There is no good way to get the oil from tank to tank. I don't have a problem buying another pump and the motor is set up with a front drive shaft that is driving nothing at this point. I may mount another pump on the front of that motor and set that system with a detent valve set at the same pressure as the other 28 Gpm two stage pump goes to the second stage would kick that pump out and the other motor and the two stage pump will finish the split. I wish they made a 28 Gpm two stage pump that was ccw driven.

 

[muddstopper]

One other thing you need to take a look at is the fluid capacity of your splitter valve. Having a lot of oil doesnt do much good if your valve cant handle the flow. What kind of valve are you calling a detent valve?? Adding another pump without providing a return to tank for excess oil is going to cause a problem quick. I am not sure what kind of valve you are referring to when you say a detent valve, but it sounds like you are saying the valve would allow oil to flow to the splitter when you want the oil and then shut the oil off, if the valve simply shuts off, how are you returning oil to tank from that pump. Post a link to the detent valve you are considering using.

 

[rancher2]

The current valve that is running the splitter from the 28 GPM two stage pump is a prince auto cycle that is not rated for more oil. I was going to use another prince open center valve on the second pump with a return to the tank and another set of hoses to the cylinder. The cylinder has four ports on it. I would have the detent on the valve kick that pump out of the circuit when the two stage pump went to the second stage and would just return oil back to the tank. I am just worried pushing more oil to the cylinder might make the auto cycle valve might not work properly. May have to use check valves on the hoses going to the cylinder from the auto cycle valve.

 

[muddstopper]

Ok, got you now. 2 control valves and manually adding more oil when you need it. Kind of a hard way to do things, but should work. Its going to take some head scratching to make everything work that way. You will need to combine flows for splitting, and then seperate flows to return to tank. You will have to add check valves to keep oil from one pump from back feeding to the other pump I still believe i would try to connect the tanks and just use a unloader valve, No extra levers to pull and no extra pumps to contend with.

 

[rancher2]

Hooking the tanks together is not really an option. Location and plumbing of the tank is the hold up on that. The real two option are see if running another pump will work to speed the cycle time up or live with 20 second cycle time.

 

[muddstopper]

Hooking the tanks together is not really an option. Location and plumbing of the tank is the hold up on that. The real two option are see if running another pump will work to speed the cycle time up or live with 20 second cycle time.

You might have another option. Since you are looking at buying another pump, why not just buy a double pump. Lets say you buy a double pump, one section runs 30gpm, the other section flows 15gpm. By using a unloader valve, you could make those two pumps work like a two stage pump. You run the 30gpm as your high speed low pressure pump, and then the 15gpm pump as your low speed high pressure pump. Set your unloader valve at around 1000psi to dump the 30gpm back to tank when the pressure reaches the 1000psi setting. The 15gpm pump you could set the relief on that pump at 3000psi. This way you would be pumping 45gpm to the splitter cyl until the pressure reached 1000psi and then have 15gpm at 3000psi for anything that needed that amount of force to split. I would guess that since you have a 6.25in bore cyl, you would probably be able to split pretty much everything at 45gpm@1000psi and not really see the high pressure low flow side of this setup. This way, you could use just one of your hyd tanks. You would have to add another suction port and possibly another return port. You would have a cycle time of around 8 seconds and about 46tons of splitting force. Even at 1000psi you would have 15tons of splitting force, which will split most of the wood I would encounter. Granted you autocycle valve is only rated for 25gpm, but I believe that flow rateing is for 3000psi pressure, Under a low pressure I would bet that the flow rate could be increased. Dont take my word for that tho, you might want to call the manufacturer of your valve to find out for sure.

 

[kevin j]

Interconnecting the tanks would be a last resort and require a huge interconnect line since there is only graivity head difference. Also can overflow if the machine is on a hill, depending how long it is.


Here is another option: Use a regeneration valve on the cylinder. It connects return oil from the rod end back to closed end. The force and speed are then that of a 3.75 ram (oil pushing on rod area only.) However, it does NOT work in the retract direction at all, so retract speed would not be improved.

Regenertation would speed up the first part of cylinder stroke a lot. Run the calcs with the 28 gpm at 3.75 bore.
The high volume flows and plumbing are only between rod and closed end, the main control valve still only sees the same flow as now.
Would take a little tuning, but you would set it up as for example regen flow until 800 psi, then rod end connects to return as usual and you stay on two stage until 1000, unload large section of two stage at 1000, run on small section until 3000, and across main relief at the flow of the small section at 3000 psi.

You mentioned I wish someone made a 28 gpm two stage with your rotation. Make one yourself with the two section pump of the right rotation, external plumbing a check valve and an unloading valve. That's how two stage is done until the specific logsplitter pumps combined and the stuff into one housing. Lot more production volume to justify the cost and weight savings vs. the tooling for the splitter pumps, but other types of circuits needing two stage still do the old way with connecdting parts. Or is there more to this than I recall

 

[muddstopper]

Kevin, have to ask, how would you use a regen valve along with his autocycle valve. Regen will speedup the speed on extend only but also at a scarifice in power. I think one other thing also needs to be considered. His 2stage pump is mounted on a 20hp engine, that doesnt leave a lot of hp to run a single stage pump of any size and pressure. I am thinking that if another pump is added to his system, most likely he is going to have to swap his pumps off his 40hp engine onto the 20hp engine. Running just the conveyors saw motor and log clamps, the pressure needed might could be handled by the 20hp engine. He could use just the front pump section of a double pump and piggyback his 2 stage log splitter pump off the back on the 40hp engine. Would be a weird setup, considering that he could endup with a 3stage setup with pressures. I think max pressure on the low pressure side of the 2stage pump is about 900psi. setting the unloader valve at 900psi and using his 2 stage pump as his high flow low pressure pump, he could use a 15gpm front pump as his high pressure pump. Now one also has to take into consideration the 2stage pump is rated at 28gpm@900psi at 3600rpms. I dont know what kind of 40hp or 20hp motors he has, but if it isnt turning 3600rpms, then hes not getting the full flow potential out of his 2stage pump.

 

[rancher2]

Some thought was given on using regeneration. Not to sure how the auto cycle valve will like it. The 20 hp is running at 3600. The 40 is running at around 3,000 to 3,200 that what the pumps on the 40 are rated at. Where the 40Hp motor is mounted I only have room for one pump on the front with out a major change. On the back of the motor I am all ready running two pumps that are bolt together and I don't want to mess with that set up. I think I will add a 20 Gallon or so pump to the front and use a brand hyd valve LS755T4JRHHA valve that has pressure release detents on both extend and retract.

 

[ChoppyChoppy]

I don't understand why you are using 2 engines. I can't imagine that would be very fuel efficient, never mind the extra noise, heat, exhaust, etc as well.

Why not use one engine large enough to run everything and power multiple pumps or even just one large one?

 

[muddstopper]

Ranger, check out this video, , you can skip to about the 20min mark to for the unloadervalve discussion. it also talks about regen extention

 

[rancher2]

Valley Firewood. Some times you use what you have. This machine will only be doing 15 to 20 cords a year so I am not worrying about the gas cost. The 2o hp engine was on the donor wood splitter. The 40 hP was a very good deal. It would probably run the whole machine. I almost bought a 120 hp combine power unit but the trailer this is all on doesn't really have the room for a large engine. If I was in the firewood business I would have done this a different way. Every thing always comes down to time and money.

 

[muddstopper]

I can certainly having to make due with what you have or can find. I have been working on my processor for about 5 years, mostly just scrounging parts. Things get very expensive once you decide you have to have it right now.

Since you already have the processor working, you should be able to calculate what the pressure and hp requirements are, and make a determination if the 40hp engine will pull everything. I suspect it would with the right setup. I think your decision to add another control valve to control flow from the extra pump you are planning isnt the best ideal. Every lever type valve you add is going to take another set of hands to operate. I think you will probably get tired of all the extra hand action pretty quick. A good unloading valve wont cost much more than buying another control valve with detents, will do the same thing you are wanting to do with the control valve, and you wont need another hand to make it work. I also feel that future upgrades should be to make a hydraulic tank that will supply all the pumps. If you had the bigger tank now, you could pull the extra oil for your splitter circuit off the saw circuit and not need to buy and mount another pump. You would still need the unloading valve to make it work right. These are just my honest opinions on what changes I would make. Your way will work, just not the best setup.

 

[ChoppyChoppy]

I would imagine so, though without actually seeing what you are trying to build or having all the specs for the hydraulics it's hard to say. My processor is powered by a 35hp Kubota engine. Nice engine.. fairly quiet and sips fuel... about a gallon an hour.

How big of a bar are you running?

Just seems like having to setup 2 engines, 2 hydraulic tanks, several different pumps, etc is alot of headache.

A 6.5" ram is pretty big, what about using a smaller ram and not having to buy more parts to to make the ram you have work?

Valley Firewood. Some times you use what you have. This machine will only be doing 15 to 20 cords a year so I am not worrying about the gas cost. The 2o hp engine was on the donor wood splitter. The 40 hP was a very good deal. It would probably run the whole machine. I almost bought a 120 hp combine power unit but the trailer this is all on doesn't really have the room for a large engine. If I was in the firewood business I would have done this a different way. Every thing always comes down to time and money.

 

[muddstopper]

A 6.5" ram is pretty big, what about using a smaller ram and not having to buy more parts to to make the ram you have work?

Not a real bad ideal, especially if you dont need all that power to split your wood.