Splitter question

[handirifle]

OK got it, thanks. Ha! On the valve. I just filled it. Lesson 1, do NOT clean it before filling it......grrrrr A 5 gal tub of fluid. a funnel. and open and pour, right? Nope, gurgle gurgle gurgle, gurgle knocks funnel out of fill tube, fluid goes ALL OVER splitter.

Finally get mess cleaned up, start and test. One fitting on the inlet of filter leaks. loose as a goose, duh. Of course fluid now spills again, when I take things apart to tighten the street el like I was supposed to do the first time.

Clean it AGAIN. Then test. All is well, finally. Yes a valve, or two would have been a good idea.

Maybe when I build my 15hp one?

 

[Texasmark]

HP and tonnage are not related in the case of splitters. I could make a 100 ton splitter with a 3HP motor if I wanted.

Very simply in the world of splitters, they all run nearly the same PSI, so "tonnage" is about cylinder diameter only. roughly 4" = 18-22T rated, 4.5" = 25-28T rated and 5" cylinder = 34-37T rated.

HP allows you to run a higher flow rate pump, so it will cycle quicker, but dont change the tonnage unless pressure or cylinder diameter change.

You typically see more HP on higher tonnage machines because they have larger cylinders, and need more FLOW to have a decent cycle speed.

Looking good on the build. 3/4" is fine for suction. Afterthought, but I have a valve on mine incase I need to pull a pump.

My way of thinking says that the area of the cylinder x the hydraulic pressure = # force applied to the ram. Then the # force is applied to the log which strikes the ram and the splitting pressure is in psi. So the blade needs to be sharp on the end to minimize the square inches of contact and maximize what # force you have. But I believe in popping the log open so that means getting a little steel in the wood and then with a wedge which starts about an inch back from the tip force the log apart.

Area is radius squared x ratio of diameter to circumference....pi....22/7.

So (4"/2) exp 2 x 22/7 = 12.57 sq in (area of the piston) x 2k (hyd pres) = 25,000 # force. Dividing by 2000 to get tons = 12.5 tons force.

That was my dilema. I was looking for about 25 T when I started my project and when I settled on a 4" max x 24 cylinder, I was locked into 12.5.

So I did the next best thing. It took 3 iterations to do my wedge, but it is a wedge with a knife point followed 1" down the blade with a 30 degree expansion (wedge) and haven't seen anything I can't bust with it....with a little grunting.

So I don't know where the 18-22T rating you mentioned comes from with a 4" cylinder. If I missed something and in fact have a 25 ton then whoopee.

 

[LD1]

I said rating. As in comparison to box store models that hype the numbers.

And 2000psi is LOW for hydraulics. Most run 3k give or take

 

[LD1]

I said rating. As in comparison to box store models that hype the numbers.

And 2000psi is LOW for hydraulics. Most run 3k give or take

 

[Texasmark]

I looked up my pump specs and at 3600 it's rated at 2500 nominal 3.5 gpm in the high pressure mode......."locked rotor" rating is 3000. So my 12.5 ton guesstimate increased by 25% all the way up to 15.7 ton but seldom do 3600 rpm rated air cooled engines run 3600...now that we have tachs to monitor such. So dropping the rpms back to the 32-3300 rpm where mine normally run gets me back to 90% of that 15.7 or 14 ton. Just running numbers, assuming the flow is restricted for some reason (hose/fitting losses) then flow drops and pressure increases. Taking the max pressure I'm at 18.7 which reaches the range if my engine is running 3600. But that's close enough. Course with 8 hp required to make the pump perform as spec'd and having twice the hp available, it ought to do 3600....no tach on this engine. That and my wedge get-r-done so I'm ok.

 

[LD1]

It's don't matter what the pump is rated at. Pumps don't make pressure they make flow. Restriction makes pressure. Infinite pressure will build until restriction is removed. To keep things in check, that's why we have prv's. So whatever yours is set to crack open at is what pressure you will have provided you have the HP to build that. Never heard of a "locked rotor" pressure for a pump??

And not running full rpm has no bearing on tonnage. Tonnage is pressure and cylinder bore. Pumps don't make pressure. Has no effect. 3200 will make the same pressure, just flow a lower gpm. (Make it extend and retract slower).

But all that aside, I will say it again. I did not mean to imply that a 4" bore splitter will actually make 18-22t. The numbers I listed are just what mfgs commonly "rate" them at. I mentioned that for comparison purposes only.

 

[handirifle]

LD1
Following this little back-n-forth here, could the locked rotor pressure he mentioned be if say the piston meets an unmovable force, and at 3000 oil starts to leak by the pump gears internally? I am only guessing here because I really do not know. Just a thought.

While we're on the subject, what combination would one suggest if later on I want to build a bigger one, using my 15hp Briggs engine? Would like tonnage as high as possible, BUT a fairly fast cycle time (unloaded of course) would be desirable as well, say less than 10 sec out and back.

 

[LD1]

Never heard the term locked rotor with a hydraulic pump, so I'm not gonna speculate on that.

For your splitter, tonnage is limited by only cylinder diameter and pressure. Increase either and tonnage goes up. You have to consider the safe working limits (psi rating) of everything else. Cylinder, valve, hoses, etc.

HP requirements are (gpm x psi)/(1714 x efficiency)

Efficiency is usually 0.85

So looking at the formula, more power can allow you to go with more pressure or more flow(speed) or a combination of both staying within the HP requirements.

Since most splitter components and 2-stage pumps are in the 3000psi range, getting more tonnage isn't likely with current cylinder. So use that HP to gain speed.

22gpm 2-stage is a good combo. Jumping to a 28gpm adds a alot of cost, is borderline with 15hp, and little to no gain over a 22. Cause a 22gpm is already taxing the limits of port sizes on a 4" cylinder and standard 25gpm valve and associated fittings.

Only way a 28 would benefit is custom cylinder with large ports, and a 50gpm valve. Again....costly for the little gain.

My 22gpm 4" cylinder w/2" rod and 24" stroke runs 7.9-8.0 seconds out and back. At 3600rpm it calculates that it should be about 6.3 seconds. I don't think my motor is running quite 3600, and again, taxing the limits of the -08 orb ports in the cylinder.

 

[handirifle]

Thanks. I figured I would step up to a 5" cylinder, if I built new and had a 22gpm pump in mind. I figure a 24" stroke is more than enough. I would not use the 15hp on this unit, since the little Honda does fine. Not the strongest unit going but it works. Was just thinking ahead.

 

[Texasmark]

I used the locked rotor term which is an electrical term for motors when the current is max just the instant before the voltage starts to fall off caused by a load so large that the motor's rotor (armature) can no longer rotate aka locked. That's the way they rate motors nowadays so you think you are getting more than you are really getting when you consider Volts x amps x power factor, x efficiency of the motor and 741 watts per hp. So I just used that terminology not being a pump guy.

Not familiar with the name for a gear pump when the output is blocked and it's locked to a driving motor with adequate hp. Assuming the flow is stopped, the motor is still turning/attempting to turn the shaft of the pump, the fluid is being compressed but not moving, or moving at a lower rate than the pump's rating. This puts pressure on the pump (head pressure) requiring more hp from the drive source, pressure goes asymptotic if blocked completely and something would blow up if it weren't for the PRV built into the pump. Yes I think mine is 3k psig but that is not the working pressure of 2500 under normal loads.

From your post LD, "My 22gpm 4" cylinder w/2" rod and 24" stroke runs 7.9-8.0 seconds out and back. At 3600rpm it calculates that it should be about 6.3 seconds. I don't think my motor is running quite 3600, and again, taxing the limits of the -08 orb ports in the cylinder."

That's exactly where I am with my rig (8-7 seconds out-back) as I stated earlier in this posting but with my "posted" 16 gpm pump on what seems to be the same sized cylinder.

So I guess I'm getting what I should out of my junkyard kludge.

Thanks for the chit chat.

Handi: On 24 in, I used that because my logs have to be no more than 22 to fit my stove and on going to 5" weight and cost were prohibitive to me besides requiring a larger gpm pump to get the cycle time down. Again, I started this kludge of mine because my Ford tractor was only running about 7 gpm at WOT....30 hp tractor doing a 8 hp job; not very efficient in fuel and wasted time.