log splitters and hydraulics

[okietreedude]

A while back, there was info passed along about the 'false info' of tonage on log splitters - dont remember the thread or participants so heres a dedicated thread.

I just bought a '35 ton' splitter - has a 5" ram w/ 26" stroke, 16 gpm pump, 14 sec cycle time.

my question is: Can i speed this up? If so, how? Bigger pump and if so, how big? If i put on a bigger pump, does the operating handle valve need to be bigger too?

Here's the website for more info: http://www.speeco.com/products.php?id=95&id2=512&prod=357

 

[sotc]

How big is your engine and what pressure are you running?

 

[okietreedude]

The engine is a briggs/stratton 1450 series. I guess they dont display them in HP anymore, why i dont know.

I have no idea the pressure, wouldnt know how to check or where to look.

 

[okietreedude]

Engine is 342cc

 

[sotc]

Theres a formula that requires hp, psi and I think gpm.

 

[CurSedVoyce]

And Carl probably has it in his head

 

[lumberjack]

Assuming American units:

Force= radius x radius x 3.14 x psi

Hydraulic hp= gpm x psi / 1714

Gallons to stroke cylinder= radius x radius x 3.14 x stroke length/ 231


I just got out of my chair and into the bed, so I'll soon be back asleep, but the easiest way to get a faster cycle time is put a smaller cylinder on it. I suggest a smaller cylinder with quick connects the hoses and the largest rod you can practically find.

@3 ksi
5"cylinder= 29.4 tons
4"cylinder= 18.8 tons
3"cylinder= 10.6 tons

Divide the new cylinder tons by the old cylinder tons. Multiply that by your old cycle time to get the new cycle time (approximate, rod size matters!). A 3" would cycle in roughly 5 seconds.

Night night.:cool:

 

[FJR]

To figure the real tonnage you need the area of the piston and the pump psi rating. You say your piston diameter is 5":

5^2 * 3.14 / 4 = 19.625"

Now once you find out the pumps psi all you have to do is multiply it by 19.625. That will give your rating in pounds. Then divide by 2,000 to get tons.


As far as calculating speed, here is a sweet site to use. Bookmark it.

http://www.calculatoredge.com/mech/speed%20hydraulic%20cylinder.htm

 

[treesmith]

And Carl probably has it in his head

Could that possibly explain the rattling sounds I hear when he turns his head suddenly?

 

[Al Smith]

FWIW the only manufacturer that puts out true information on tonnage is Timber wolf .The rest embelish the facts .

As Carl pointed out at a full 3000 psi a 5 inch is 29 tons .At the pressure they actually run at it's closer to 22 tons if you want the true facts .

Now granted for a very short period of time it could reach 3000 until the relief valve opens but it's very short .

To the question the only way to make it run faster is either over speed the engine or go to a larger pump .Larger pump most likely would entail a larger engine else you could just flat stall it out .Catch 22 ,just run the thing .14 seconds might sound like a long wait but it's fast enough to wear you out feeding wood to it .Try it for a couple hours ,you'll see what I mean .

The pressure setting on the relief has nothing to do with cycle speed .That's strictly a product of gallons per minute flow or liters (litres) for our metrically inclined friends .

 

[lumberjack]

I don't know what pressure the system runs at. To get the rated tonnage it would need roughly 3600 psi, or 20% over "standard". There isn't any reason a system couldn't be designed to run at that pressure.

I still think the easiest thing would be using a smaller cylinder until you need more power.

 

[CurSedVoyce]

Could that possibly explain the rattling sounds I hear when he turns his head suddenly?

My theory is that sound is the keys to the vault that traps all that information that he ingests.

 

[Marc-Antoine]

There is an other way I'm thinking at. It should be very handy ( but expensive too).
For the same power, you can have the high strength and the higher speed, but not at the same time. It's classic, the tricky part is to play with the both sides in one cycle, with efficiency if possible.
Usually many manufacturers put a double fixed pump (high and low displacement) with a pressure switch valve to do that, but the efficiency is far from the optimum.

You keep your motor and your cylinder.
So you have the smallest engine to do the job with a reasonable gas consumption (most part of the working cycle is waiting and running at low pressure, so you don't waste too much energy for nothing).
With your cylinder, you get the max strength to split big knotty rounds.

You replace the pump by a bigger one, a variable displacement piston pump. The nice trick is to put a load sensing system in it to manage the available power. The pump adapts itself (progressive low / high displacement) accordingly to the energy needed by the cylinder. With a factory rated system, the pump follows mostly the exact curve of the pressure-flow relation for the engine's power.
- free movement (forth or back), low pressure needed, the pump is set in max displacement, the power is used to give high flow and fast travel.
- the wedge hits the wood and stalls, the pressure rises, the pump moves in a low displacement (almost zero if needed), the power is all used to give high pressure and brute strength, but at a very low speed.
- the wood breaks, the pressure drops partly , the wedge continues is way through the wood (high friction but not a dead stop), the pump adjusts to follow the effort's variations, providing more speed when there is less strength needed, and vis versa.

By this way, the motor can run at full load nearly all the time (excepted in the waiting phases) which is ideal for the output, you get the shortest time cycle possible with the biggest efficiency. The splitter does the job you want, either easy or tricky wood, without wasting a monstrous amount of gas in a monster motor, nor waiting an hour to split tooth picks.

 

[Al Smith]

FWIW most detent splitter valves are factory set at around 2300 PSI . Most two stage pumps use around 600 as the transfer pressure .

From own experiance in compairing my homebuild with a 5 inch cylinder and Toms factory machine with a 4 inch cylinder they cut at about the same speed .Mine has a 16 GPM pump ,his an 11 .The difference being his machine on tough wood shifts to high pressure low volume sooner than mine which usually takes it through in low pressure without shifting .Thus the cycle is about the same .

Other things such as his cylinder ,pump ,hoses etc will run hot by being on high pressure while mine remain relatively cool .

Also FWIW the pressure shift valve on the double pumps are adjustable .So if you wanted you could raise the shift pressure providing the engine has enough power .From what I've seen most of those TSC 5 inch cylinder splitters are 12 HP more or less .

 

[lumberjack]

A load sensing/ constant pressure/ closed loop system would be the most efficient by far, but fairly expensive to implement.

 

[Thor's Hammer]

Asymmetric twin pumps with dual relief valves is cheap and easy to implement.

 

[Al Smith]

If you talk about a system with constant pressure like automated machine tools use you'd better have ton of money . A multi piston squish plate Vickers pump would set you back more than the price of an entire splitter .

A system like that is something you use if the requirements are for multiple hydraulic devices not a single cylinder log splitter .You run with the relief valve on pretty much constant bypass ,noisey as hell .Uses a pressure header and multiple out lets .

As far as hydraulics a splitter is just about as simple as it gets with perhaps the exception of a hydraulic jack .

 

[Thor's Hammer]

This will do the trick perfectly, designed for the job-
http://bit.ly/vcggJT

 

[Al Smith]

That's a pissy little 8 gal per minute pump .He'd really be upset with the cycle time on that thing .

 

[lumberjack]

Most splitters come with two stage pumps over here, Ed.

Al, a constant pressure system shouldn't be constantly relieving pressure. Depending the system might not even require a pressure relief valve. At times of no load the the pump's output should be near 0, only allowing for the pump's bypass and and other leakage in the system. The pump shouldn't make appreciable noise unless I'm missing something.

They are quite a bit more expensive new than gear pumps. You can find them at discounts although finding one for that small of a motor would be difficult. Another point is that with that style pump (vs a gear), fluid filtration is much more important.

 

[Al Smith]

It's the diff between a closed center system and open center ststem .Obviously on an open like a splitter if the valve is in neutral the system pressure is nearly zero .It just flows through the valve and back to the tank . Doesn't do any thing .

On a closed system like a large piece of automated metal working machinery with multiple devices the pressure remains pretty much the same in the pressure header .My term of calling it a pressure relief valve should have been pressure regulater instead because that's what it is .

You can run multiple devices on a simple open system but you need a flow divider to do it .If not with multiple valves like some tractor hydraulics the first valve in line gets all the flow which can be a pain in the butt at times .