Log splitter design.

[J_J]

While we are on this, what kind of hydraulic cylinder (Size and type) would you recommend. I keep hearing people use whatever, but wondering what whatever really is. I assume 20 inch throw, but how thick of a rod?

Carl,

Go to Surplus hydraulics in their tech help section. and you can put different cylinder widths and rod size in and see the force it will produce.

3 in bore, 1.25 in rod, 3000 psi = a push force of 10.5 ton, and a pull force of 8.5 ton

4 in bore, 1,25 in rod, 3000 psi = a push force of 19 ton, a pull force of 17 ton

5 in bore, 1.25 in rod, 3000 psi = a push force of 30 ton, a pull force of 27 ton.

You can select a cylinder based on bore size and rod size. If you increase the rod size, the pull force will decrease.

You select the length for the size of the wood you will be splitting.

 

[J_J]

My beam is 8in on the flat, 8 1/2 tall and 3/8 thickness. I figure if I spread the pressure out acrosst the beam it should hold up. Most of the brand name splitters I am seeing are no bigger. Unless there is something I am missing.

In the beginning this will run off of the tractor but after I get through this season I plan to add an 8 hp engine with a 16 gpm pump. I jus need to get my wood for this year split then I will have the time to add the goodies.

Hp to drive hydraulic pump = Psi x GPM / 1714

In order to power a 16 gpm pump at 3000 psi, it would require 28 hp.

Your 8 hp will only power a 5 gpm pump.

Check out the tech help section at Surplus Hydraulics.

 

[Rio_Grande]

Not disagreeing with you, but I was under the understanding and thought I had done the math (although I cannot find it in my notes) that said 5hp will run 11gpm and 8 will run a 16gpm. I may be wrong and I know there is a diffrence between a regular pump and a 2 stage pump. The 2 stage pumps require less hp to run.

Again I am just learning this stuff as it pertains to small engines. I am used to having a pump running off of a tractor and not running off of a small hp engine.

Jeff

 

[J_J]

Two stage pump will operate at two different pressures, and different gpm.

Minimum HP: 5
RPM Requirement: 3600
For use with open center hydraulic systems only
1st Stage: 11 GPM@650 PSI
2nd Stage: 2.9 GPM@2500 PSI

They rate that pump you refer to as a 16 gpm pump, but at low pressure around 650 psi. That section of the pump is for fast mode, but when it senses some resistance, it switches to high pressure and low volume, and that why it slows down.

 

[Rio_Grande]

That makes a little more sense than the way it was explained to me.

So I can run a 2 stage 16 gpm pump with the 8 hp... I actually found if I can mount the pump vertical I have a rebuilt 12hp sitting in the shop floor I had forgoten about.

Jeff

 

[J_J]

That makes a little more sense than the way it was explained to me.

So I can run a 2 stage 16 gpm pump with the 8 hp... I actually found if I can mount the pump vertical I have a rebuilt 12hp sitting in the shop floor I had forgoten about.

Jeff

You can use it, but it is not a good match.


To find out the HP required.

GPM X PRESSURE DIVIDED by 1714 = HP REQUIRED

Example 10 GPM X 3000 PSI DIVIDED BY 1714 = 17.5 HP

16 GPM X 3000 PSI DIVIDED BY 1714 = 28 HP

To find pump size.

HP X 1714 DIVIDED by PRESSURE - PUMP GPM

EXAMPLE 8 HP X 1714 DIVIDED BY 3000 PSI - 4.57 GPM PUMP

8 HP X 1714 DIVIDED BY 1500 PSI- 9.14 GPM PUMP


I have three hydraulic pumps on my Power-Trac. 12GPM, 3 GPM, 15 GPM.

30 GPM X 2500 PSI DIVIDED BY 1714 = 43.75 HP

I have a 45 HP engine, So if all pumps are working at 2500 psi, I don't have much reserve left. So if I try and overload the system, I run out of HP.


If anyone finds this in error, please correct.

 

[SPYDERLK]

You can use it, but it is not a good match.

To find pump size.

HP X 1714 DIVIDED by PRESSURE - PUMP GPM

EXAMPLE 8 HP X 1714 DIVIDED BY 3000 PSI - 4.57 GPM PUMP

8 HP X 1714 DIVIDED BY 1500 PSI- 9.14 GPM PUMP

If anyone finds this in error, please correct.

I guess you were saying the 12 horse isnt a good match cuz the above example of yours shows the 8HP is since a 16gpm delivers about 4gpm when it shifts to the low displacement mode.
I think the 12hp will be a good choice tho because with the 4" cyl he wont be using full rpm much and an 8hp probably would be short on torque to be able to deliver full pressure at lower than its nominal work rpm. The extra displacement of the bigger engine, on the other hand, will provide enuf torque to run the pump at any chosen rpm. He just wont ever need all its horsepower.
larry

 

[J_J]

I guess you were saying the 12 horse isnt a good match cuz the above example of yours shows the 8HP is since a 16gpm delivers about 4gpm when it shifts to the low displacement mode.
I think the 12hp will be a good choice tho because with the 4" cyl he wont be using full rpm much and an 8hp probably would be short on torque to be able to deliver full pressure at lower than its nominal work rpm. The extra displacement of the bigger engine, on the other hand, will provide enuf torque to run the pump at any chosen rpm. He just wont ever need all its horsepower.
larry

You are correct.
Sometimes I forget to switch the psi figures.

For use with open center hydraulic systems only
First Stage: 16 GPM @ 650 PSI
Second Stage: 3.5 GPM @ 2500 PSI
Maximum pressure: 3000 PSI

16 gpm X 650 psi divided by 1714 = 6.0 hp

3.5 gpm X 2500 psi divided by 1714 = 5.1 hp

A minimum HP or 8 would be required

If your pump could pump 16 gpm at 3000 psi, you would need 28 HP

 

[moeh1]

I built my own (twice).
Some observations for what they are worth to your own personal situation.
I used a ~6 HP wisconsin coupled to an 11 GPM 2 stage pump, running a 3-1/2 by 24 cylinder.

I stepped down to 3-1/2 for cycle speed. Occasionally I would hit relief and have to spin or flip the log, but in 20+ years of use, I have thrown aside less than a face cord that wouldn't split. Those ended up in our outdoor fire ring anyway so they weren't lost. The 6 HP allowed me to run most of the time at ~2/3 throttle and get good cycle time and enough power with less noise.
I made my horizontal/vertical and I'd say that over 95% use was vertical. Even with a bad back, it seemed easier to work that way, especially when working with big diameter stuff. If you want vertical, that means that the sliding element has to be the wedge.
If you want a horiz/vertical, build the entire I beam section, retract the wedge and then put a pipe under the beam to find the seesaw point - that is where you will want to put your pivots. If you start the splitter and extend the ram, the whole thing will stand up by itself.