2 stage pump question

[Dave M7040]

There is a reason commercial ones use two pumps.

2-stage pumps shift from high to low based on the pressure demands of the system.

The splitter ram is the biggest cylinder in the system, and thus the slowest. So you want the high speed when its retracting....or when its extending but prior to making contact with wood/wedge.

With a processor, its like a backhoe. You are running multiple functions at the same time. IE: you may be lifting the log lifter , running the saw, and retracting the ram all at the same time.

Doing so will likely cause the pump to shift into high pressure / low speed mode.....which will slow the ram down dramatically and you will be waiting on something constantly.

AND, typically two stage pumps dont work well with motors.

An additional comment. You are running an open center hydraulic system. It does not lend itself to operating multiple valves and cylinders at the same time.

Drive two cheap pumps off your existing engine. One the two stage the other not. Both can draw form the same reservoir. Then you truly can do two things at once like retracting the splitter wedge and raising another log up to be split.

Dave M7040

 

[polemidis]

That question may souns silly, but what are your thoughts on utilizing a small car engine? Or a motorcycle engine? There are a lot of them out there to be recycled. I cannot make Google to give me good results on that question. What could the tough complications be?

 

[oldnslo]

most motorcycle engines rely on travel speed for air flow for cooling. Not sure how well they would work for stationary application

 

[muddstopper]

The proble with car engines is throttle control. As the pumps build pressure, the engine rpms change and reducing pump flow. there are solutions, but not good ones. Another thing is that engine has to turn 3600rpms to get the maximum flow and pressures out of your pump. Do you really want to listen to that engine screaming while your splitting wood. You also have the problem of heat control, got to mount a radiator somewhere's and a fan to cool the engine, and that heat is going to surround your work area. Then add the extra weight of that engine and radiator full of water. And dont forget the fuel tank and the fact your probably going to burn 10gal of gas a day of work. Then, how do you plan on mounting the pumps to the engine, your going to have to fab all that up, nobody sells a kit. all in all for your needs, a car motor is way over kill and I believe it will cost more to setup, even if someones give you the motor, that it would cost to just buy a new small engine that will fill your needs. Now I say all that, even tho I plan on a 7.3 diesel engine to power my processor. I will be flowing 100gpm, multiple pumps and multiple operations taking place at the same time. I should have the theoretical capacity to produce 30 cords per hr, where as you are talking about 30 cords per year. And NO, I dont really think I can produce 30cords per hr, but the math says I can, under the right conditions. A true 4 cords per hr would satisfy me.

 

[polemidis]

Another thing is that engine has to turn 3600rpms to get the maximum flow and pressures out of your pump.

But you can target a lower rpm! Since there is abundance in hp, why not calculate the pump you need for 1500rpm? Yeah you are not getting the max out of the pump, but thats ok, even better lifespan for the pump.

You also have the problem of heat control, got to mount a radiator somewhere's and a fan to cool the engine, and that heat is going to surround your work area. Then add the extra weight of that engine and radiator full of water.

Bigger commercial machines should have water cooled engine anyway, no?

And dont forget the fuel tank and the fact your probably going to burn 10gal of gas a day of work.

Not for low rpms, right? Since you can target the rpms that give you the hp that you need.

Then, how do you plan on mounting the pumps to the engine, your going to have to fab all that up, nobody sells a kit.

Well, that would be a real pain for me.

And dont forget the fuel tank and the fact your probably going to burn 10gal of gas a day of work. Then, how do you plan on mounting the pumps to the engine, your going to have to fab all that up, nobody sells a kit. all in all for your needs, a car motor is way over kill and I believe it will cost more to setup, even if someones give you the motor, that it would cost to just buy a new small engine that will fill your needs.

I am looking the prices: The kohler 1000cc, 37hp, costs $2900! . the 725cc 25hp costs $1700! Thats a lot of money there!

Can you give me a hint on how you are going to take power from the 7.3 diesel? I guess you take out the transmission, right? The what do you have for an axle? Splined axle, common size? Is it about the same for almost every brand? I know we are getting out of subject of "hydraulics" I am not going to extend a lot here. I am just curious. And annoyed that I cannot make Google to work

 

[muddstopper]

Do you think you need a 37hp engine?? If so, why? According to your previous post, you stated you wanted to process 10" dia. wood, Dont sound like you need 37hp to do that. Also the .58cuin motor with a 3/8 chain should be more than enough to buck that size wood and a 4in bore cyl should supply plenty of power, even for a 4way splitting wedge. Like I have said, decide just what you want to do and size everything accordingly. Also consider, not everything runs at the same time, while splitting, you most likely will be advancing and clamping the log before using the bigger fluid demands for the saw. You wont be making max pressure and using all of your available hp. While sawing, your splitter will be retracting and not using a lot of hp either. I have seen plenty of factory processors with 20-25 hp engines and they all will saw and split bigger wood than what you are suggesting, Heck, most will split up to 20in dia.

As for my 7.3, its 190hp, my double pump is 33/42gpm. My splitting cyl are 4.5in bore and I am using two of them mounted together, 50tons of splitting force. I am building a knuckle boom loader to load logs with, I have a 18ft conveyor to load the splits into double and triaxle dump trucks. My splitting wedge is a 12way box wedge design and is capable of sawing and bucking 30in dia rounds x 30in lenghts. My saw motor is 1.2 cuin, axial piston motor, pulling a .404 chain, and I can turn the pressure up to provide 50+hp of sawing power. My control valve is a V70 rated for 70gpm flow and has lever as well as air shift spool. My 7.3 is a international truck motor and already has the factory air compressor to operate the splitting CV and the to provide air for my saw cyl. To mount the pump to the engine, I will have to make a mount to bolt it to the bellhousing and machine a stub shaft to bolt to the flywheel crank bolts. If I had of bought all the parts new, I would probably be approaching $40-50,000 in parts and materials, as it stands now, I have been able to scrounge scrapyards, done some fancy trading, and had a few parts donated and am out about $4000, but that number will continue to go up. Some parts are just plain hard to scrounge and you have to buy new, but with a little knowledge of what to look for, you can get good parts for pennies on the dollar at scrap yards.

 

[polemidis]

Do you think you need a 37hp engine?? If so, why? According to your previous post, you stated you wanted to process 10" dia. wood, Dont sound like you need 37hp to do that. Also the .58cuin motor with a 3/8 chain should be more than enough to buck that size wood and a 4in bore cyl should supply plenty of power, even for a 4way splitting wedge. Like I have said, decide just what you want to do and size everything accordingly. Also consider, not everything runs at the same time, while splitting, you most likely will be advancing and clamping the log before using the bigger fluid demands for the saw. You wont be making max pressure and using all of your available hp. While sawing, your splitter will be retracting and not using a lot of hp either. I have seen plenty of factory processors with 20-25 hp engines and they all will saw and split bigger wood than what you are suggesting, Heck, most will split up to 20in dia.

No absolutely not, I do not need 37 engine. But the 25hp, would allow me to be in a comfort zone. But $1700 is way to much. On the other hand my 16hp duromax is on the low edge. Paid $179 brand new, so I can't complain! But I do not know yet if I can sustain a conveyor. It should run at the same time with the saw.
My questions about the car engine were more curiosity than need. The mounting is enough headache for mr to stay away even if I could find a cheap 25hp motorcycle engine.

Anyway, I will proceed with the math as soon as I have a good looking CAD. Worse case scenario is to upgrade to the 22hp gas engine of HF with $700 if the 16hp is not enough. But I am far from calculating that.

Thank you man, I am a lot more confident now. I have a lot less dark areas.

 

[MossRoad]

Remember that a motorcycle engine produces that HP at a very high RPM and has little torque, comparatively speaking.

What kind of 16hp motor do you have?

 

[MossRoad]

For example, my '77 two-stroke twin Yamaha RD400 put out something like 43HP @7100RPM in stock configuration. After extensive mods, it put out closer to 60HP @10,000RPM+. It could pull 11:92 @119MPH in a quarter mile. But I could hold it back and do burnouts with just a little bitty hand brake on a thin front tire and my feet on the ground. Plenty of HP, NO torque from a 400CC engine. My Kohler Comand Pro is something around 700CCs and only 25HP... but only runs at 3600RPM.

There's a reason many of these machines are powered by these 3600RPM air cooled engines.... they work. Keep it simple and use what's already been designed.

 

[muddstopper]

For example, my '77 two-stroke twin Yamaha RD400 put out something like 43HP @7100RPM in stock configuration. After extensive mods, it put out closer to 60HP @10,000RPM+. It could pull 11:92 @119MPH in a quarter mile. But I could hold it back and do burnouts with just a little bitty hand brake on a thin front tire and my feet on the ground. Plenty of HP, NO torque from a 400CC engine. My Kohler Comand Pro is something around 700CCs and only 25HP... but only runs at 3600RPM.

There's a reason many of these machines are powered by these 3600RPM air cooled engines.... they work. Keep it simple and use what's already been designed.

I agree whole heartly. I think he can make it work with his 16hp engine, as long as he sticks to the 10in wood that doesnt need a lot of power to cut or split. Trying to throw a 28gpm two stage pump on a 4in bore cyl is just wasteing money. The senario I wrote earlier, with the double pump setup and a unloader valve would seem his best option. Heck with 10in dia wood, I doubt he would ever see the 2000psi it would take to kick the unloader valve out. If he did, it wouldnt be very often.

So you dont have to go back and find what I wrote.

With the right setup, you can do a lot more with a 16hp engine and a high low pump setup than you might think but there is a compromise. The 28gpm 2 stage pump only rated for about 900psi at full flow. Then it drops down to about 8gpm@3000psi. I aint going to do all the math, but using 2 single stage pumps with a unloading valve would allow the use of up 12gpm@2000psi, which should be enough flow and pressure to run a hyd chainsaw with one pump and set the other pump at 8gpm@3000psi for high pressure for the splitter and with the combined flow still have 20gpm for high speed. The compromise is you only have 20gpm at low presssure instead of 28gpm with the two stage pump. The advantage is you are able to pump enough oil at a decent pressure range to run a hyd chainsaw. The 12 gpm@2000psi will get you in the ballpark using one of these motors, .7 cu in Parker MGG23-BB1B3 Hydraulic Motor | Parker | Brands | www.surpluscenter.com, which personally I think would be the minimum size motor I would use for a hyd chainsaw. Going with a 20hp or larger gas engine would allow for a better motor as well as bigger pump choices. A 25hp engine will get you in the 18gpm@2000psi for a chainsaw motor and would allow you to use a 1.2 cu.in axial piston motor and make about 23hp of chainsaw. Throw a big 14pin sprocket on the saw motor, a ,404 chain and cut with the big boys. You would also be able to run a 18/12 double pump setup and potentialy have 30gpm of oil to split with. Anyways, just a few thinks to think about.