thank you about that i was wondering if that would be too much -- and my cycle time is very very good right now -- i will be happy with it as it is -- thank s again

 

Ken:


Thanks so much for getting all those specs together! I would definitely like to see pics of your machine, when you get a chance. I am looking for a used splitter with a bad engine, just as you did. I was planning on using a 5hp. compressor motor, at 1725 rpm, then gearing up with a belt drive, but I never considered the side-load-rated bearing issue, either. I just know I need a 5hp, single phase motor to repower a 3 phase compressor I was given, and I hoped that, where I found one, I'd find another--still looking, however.

Torque1st: Who are you, Doc Savage--LOL! Sheesh, I'm over in an electrical post re: speed controls, and you laid it down, hard info, for all to see, and I figured, now here is an electrician/engineer type guy. Then I'm reading your excellent analysis of hydraulic system design over here. (Makes me wonder what good a liberal arts education is, really )

At least now I know what you do but tell me, is all that elect. theory knowledge part of the normal background for designing hyd. systems, or do you have more than one specialty?

I'm not mocking or dissing you at all, brotha...having English and law degrees (i.e., Liberal Arts), but wide technical and science interests (I just can't do higher math) I'm just honestly fascinated by experts in fields I only muddle through to pursue my own varied ends. I'm not yet up to a "jack of all trades" status--I started with the "master of none" part and so far, I'm lookin' strong in that dept.-lol! I just like learning stuff that is interesting to me, like a lot of these threads right here, and I kind of marvel at the depth of expertise here and on a couple of other sites I cruise.

And thank you for your analysis...I didn't know if Ken was gonna return, but even though he did, it's definitely helpful, especially that side-load bearing issue. I've read about before in the small engine world. I believe some engines cannot be adapted to other applications for that reason--some crank bearings were not designed for thrust loads, (vs. side loads) for example, I believe it was.

Hey, here's a question: What is the formula one uses to calculate hyd. ram tonnage output? I (think I) know you take the surface area of the I.D. of the ram X the line pressure, but then what? I couldn't get your numbers using pi or not using pi.

Peter

 

I have tables that I use that are quicker than running a calculation but they are rounded off some and so are my answers. Plus tables make it easy to come up with an estimate of the pressure and cylinder sizes that will be needed to do a job.

I am just an old engineer that has picked up a lot of on-the job training thru the years when I had to. Also a "master of none".

The formula for cylinder force is just Area X Pressure. There are adjustments for seal friction etc but they are usually negligible for your use.

-BTW, the basic laws for electricity and hydraulics are the same, just different units.

kmrs75 came back with the info that it was a 4" cyl with 2-1/2" ram which is a std cylinder size. At 2500 PSI it will produce 31,418 pounds of force, or close to 16 tons. It will pull with 19,146 pounds at 2500 PSI. The ram will travel ~250"/minute out and ~400"/min retract at 13.6GPM. The blind end cylinder flow will be close to 23GPM on retract, if the lines and control valves will not handle that flow it will go into high pressure (slow) mode on retract.

 

Torque1st:

Well, thanks for satisfying my curiosity re: your background. I guess it pays to pay attention, huh? IOW, you've picked up a heck of a lot along the way.

Re: hyd. force, my numbers were different from yours by about 1/3 or more, so I don't think it's a matter of rounding up or down.


If "[t]he formula for cylinder force is just Area X Pressure," then I'd like to do an example, to show you what I was thinking:

3" I.D. cyl. X 3.14 (pi, right, roughly?) = 9.42 sq. inch. of piston surface.

9.42 X 2,000 psi = 18,840 lbs. , Dividido by 2,000 (to break out tonnage) = 9.42 tons. Is that right? B/c my buddy just bought an 8 hp. splitter that claims it's 34 tons. I don't understand how they get that much pressure, if my math is right?

I know I'm doing something wrong b/c using your 2.5" pistion X 2,500 psi example, above, (with what I think pi is, i.e., 3.14) I get 19,625 lbs, or 9.8 tons.

 

For area try pi times radius squared. (pi*R^2). Diameter x pi results in circumference.

 

You need to calculate the area like the user above suggests for cylinder push. For the retract stroke you must SUBTRACT the rod area from the piston area, then multiply by the pressure.

 

ya know what i have seen allot of formulas in the last few postings and i have put some on also but the formulas are theory. they can be modified to fit the situation and application. Here I found another guy that has made an electric log splitter and his is real sharp.

I can’t send emails yet I guess I need to have more postings and be on here for 30 days or something like that so if you still want pics of mine email me and I will reply

Some quick specs that he talks about that he used

2 HP motor 3600 rpm ----- was a 5 HP gas engine

and changed the wedge from a single split to a 4 splitter because of more power

just because formulas say it shouldn’t work or might not work doesn’t always mean that

And with the tonnage of the splitter well ya know what i say BS

i had a 5 hp motor that i took off -- it didn’t have the guts to split some big pieces no it wasn’t in the best shape but that is my point if i would have kept the 5HP gas engine on there it would still be a 16 18 ton what ever even thought it would go to the max

well all i guess i am trying to say is as far as the 2 hp electric it works in real work situations and not on paper so be it

here is the web sight of the other electric hydraulic log splitter

http://ww2.green-trust.org:8383/LogSplitter.pdf

 

WOW???? Nobody said the 2HP 1725 wasn't working. You seem to be aware that the motor is being loaded momentarily beyond its capacity but as you stated it is "working" because the duty cycle is so low, it has time to cool off. MANY tools work this way. A firearm will blow up with the pressure that is put on the barrel but it will handle it for a split second, enuf time to spit a bullet out. Just don't plug the barrel.

The formulas are just pure physics, force times area. There is no need to curse at us for trying to help you out or explain to other users! 2500 PSI with a 4" cylinder is 16 Tons, today, tomorrow, and everyday, very simple math. Formulas aren't "modified" to fit the situation so they come up with different results. The hydraulic pump output pressure is what determines the force on the ram. Putting a 500HP motor on will not change that.

An electric motor does not have the pulsating one power stroke every two revolutions that a 4 cycle gas motor has. That is why they downrate to convert to electric motor HP.

That article does not list the size of the pump or the pressure. It sounds like it is working just like yours so it probably has a lower volume pump that works with the 3600 RPM motor. What was driving the pump on the loader?

 

I didn’t by any means try to come across offensively and i do apologies if it came across that way.
I was stating that anyone and formulate on paper and make something work but until it is been tried it is just an idea --

I would like to see someone else make something like this and see what they change to better it and other projects

but any way I hope someone gets something out of this -- just thought i would try to share my ideas and what worked and what didn’t --

again i didn’t mean to be rude or obnoxious

 

If you design everything to be perfect on paper it is sometimes overkill, it depends upon the application.

It helps when you make things to know where you can tweak for the gratest gain. It helps to know where the stresses are too. That is where the formula's help a lot. It keeps you from trying to push 25GPM thru a 1/4" tube also You could use a 3/4" hose on the blind side of that cylinder if you ever get a wild hair. That is a BIG pump you have.

BTW- I have designed hundreds of diffent hydraulic machines. Most worked first time, a few took some tweaks. With the high cost of new equipment and short lead times I couldn't afford mistakes.

 

Ken:

Thanks for the link--that's excellent! Makes me think perhaps a 2 hp. would be okay. Sure would be easier to find, used, than a 5hp. You're still the only cat I've "met" that's actually done what you did, and I think it's great. I'd like to see pics, when you get them. I'll PM you my email.

Eric:

Thank you for explaining what should have been obvious, I guess, re: why motors make "more power per rated horsepower" (if I can put it that way) than do gasoline engines. I never considered the effective of one power stroke per two RPM's before, comparitively speaking.

On that logic, two-stroke engines should not be derated when comparing their h.p. to electric motors' h.p., right? Have you ever seen this acknowledged in a formula, i.e., showing a different relative value b/w two-stroke h.p. and four-stroke, when comparing to motors? Just curious, as the two-stroke often gets short shrift, it seems. I don't want to listen to any engine when I split wood, but two-strokes are music to me, compared to the drone of little four stroke lawnmower engines.

 

I have never seen the derating figures for them but you might want to derate them half as much as the 4-stroke because they are still only supplying power half of the time where the 4-stroke supplies power 1/4 of the time. A big flywheel would help but then that makes them hard to get started.

-Just a guess here.

 

Makes sense--thanks.

 

BTW- If your hydraulic systems make a lot of noise let me know and maybe I can help reduce the noise. Also use a hydraulic system return filter on the line from the valve back to the reservoir. You will need a filter rated for 25GPM flow.

 

ya i do get some noise from the pump -- is it possible to make that quiter -- how would you do that