Question About Splitter Engine Speed

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turbocruiser

Feeling the Heat
Jun 10, 2011
329
Rocky Mountains Majesty
I'm sorry for so many really remedial posts but I already searched and tried to find an answer to this. I read lots and lots awesome posts by people that helped to answer part of my question which was how does slowing engine speed down affect the splitter's performance. An excerpt from one post in particular from GooseRider was:

"Note that this is a minimum engine size, nothing keeps you from putting something bigger on it, however pump output is a function of shaft rpm, so using a big engine at idle will NOT give the rated output... Most pumps are intended to run at about 3,600rpm, average full throttle speed for most small engines...."

And that helped me realize that reducing the splitter's engine speed may mean that the force of the splitter and the speed of the splitter would be reduced. Still I find that half throttle on my splitter is plenty of force and plenty of speed. So does reducing the splitter's engine speed do anything at all negative to the splitter. In other words is it harder on the pump or the cylinder or anything to do that? Whether or not it is harder on any one component, does it change things like specific setpoints of the two stage pump setup? Basically if I am happy at half throttle is there any reason at all not to run the splitter that way? Thanks as always.
 
D

DexterDay

Guest
My MTD is at full throttle all the time. If its running.

No throttle control. Doesn't bother me any. My Lawn mower has a thottle control and I run it at Full throttle 95% of the time (cutting) when its at idle, the other 5%, thats the "warm up". My mower is a 3374 Excalibur Dixie Chopper and I dont Baby it. The fastest Mower in the World for a reason.

3,600 RPM isn't that high and engines are designed to run at that RPM for extended periods. If the splitter isn't "bogging" or running rough in the cycle, then I see no harm. But I also see no harm in full throttle. I wish mine had the option just for warm up. I prefer to let an engine come up to temp slow. I dont just get in my car or on my mower and go.
 

gmule

Feeling the Heat
Feb 9, 2011
451
Conifer Colorado
Full throttle on the spliter won't hurt it because that is where the optimum horse power and torque output was designed to be at. Running below that threshold won't damage it but as you mentioned it does have lower pump
output so you will see decreased pressure and power to split wood with. If that is what works for you then run it that way. The worse thing that will happen is you can stall the engine if you exceed your power output.

Running it faster that what it is governed at will have much worse results such as shorter engine life overall or even a complete engine failure such as a broken crank shaft or connecting rod.
 

greg13

Minister of Fire
Jan 5, 2012
907
CNY
If the log is splitting easy, you obviously don't need Full power so why run the engine full tilt? Crotch sections on the other hand take more to split so turn it up!! Remember though that slower Engine speeds will result in slightly longer cycle times.
 

NextEndeavor

Burning Hunk
Jan 16, 2011
248
Southern Iowa
I run mine at about half speed most of the time unless really tough stuff. You just dont want to go so slow as to bog down the engine because that can damage it. It's quieter and uses less fuel at slower speeds. This one has an autmatic feature of dropping the engine to idle when cylinder is parked fully retracted. However, that's not of much use because I don't return the cylinder in between doing multiple splits.
 

turbocruiser

Feeling the Heat
Jun 10, 2011
329
Rocky Mountains Majesty
If the log is splitting easy, you obviously don't need Full power so why run the engine full tilt? Crotch sections on the other hand take more to split so turn it up!! Remember though that slower Engine speeds will result in slightly longer cycle times.

Right, that is exactly what I was asking. Even with all the crotch sections I've split thus far the splitter has not needed anything more than half throttle. It does go into the second stage of the pump though. But as long as that doesn't do anything negative to the splitter in terms of reliability or safety or an operational alteration that hurts things I really prefer running that rpm. So, again, that is exactly what I was asking. Thanks for all the answers thus far. I think I should probably post the full post from that one thread where GooseRider was explaining some stuff. It was an awesome summary statement, I thought, of splitter specs.

Tonnage is strictly a function of max hydraulic pressure and cylinder diameter - The usual max on most hydraulic systems is 3,000psi, which makes 29.4 tons w/ a 5" diameter cylinder. Many splitter co's exaggerate, but that's what the physics say... Some also seem to run higher max pressures, which may be pushing their components awfully hard. Of course watching the pressure guage on my machine, it's sort of a moot point, as I rarely encounter a round that needs more than 1500-2000psi to crack open - the only time I go to 3,000 is if I hit the end of the cylinder and don't let go of the valve lever...

Cycle time is determined by the gpm of the pump and the cylinder size - how many gallons does it take to fill the cylinder, and how fast can the pump move them...

Horse power needed is determined by the gpm of the pump - an old fashioned single stage pump needs 2hp per gpm at maximum pressure. Modern splitters use two stage pumps, which is sort of like having transmission gears - in high range, you get a lot of volume at low pressure. In low range, you get a lot of pressure, but low volume... Low range is essentially what you have all the time with a single stage pump. The actual numbers have a 4-1 difference in the gpm ratings - with the advertised number being "high" range - so when you see "16gpm pump" that means it pumps 16gpm in high range, and 4 gpm in low range. Thus you still need 2hp per gpm in low range, but only need 1/2hp per gpm in high, so the minimum hp for a 16gpm pump is 8hp, with most companies using 9hp to give them some margin.... Note that this is a minimum engine size, nothing keeps you from putting something bigger on it, however pump output is a function of shaft rpm, so using a big engine at idle will NOT give the rated output... Most pumps are intended to run at about 3,600rpm, average full throttle speed for most small engines....

Going back to your splitter, I would guess that you either had an oversized engine, and a 16 or 22gpm two stage pump, or about a 12gpm single stage pump. Can't guess about the tonnage w/o knowing the cylinder size though...

Gooserider
 

smokinj

Minister of Fire
Aug 11, 2008
15,980
Anderson, Indiana
Mine adjusts on its own and will grunt quickly when it needs to!
 
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Corey

Minister of Fire
Nov 19, 2005
2,595
Midwest
There is nothing really 'magic' about hydraulics. It's probably best to just think of it as a gearing system. If the engine runs slower, the splitting happens slower. If you have a big pump, that is like a higher gear. If you have a big diameter cylinder, that is like having a lower gear.

Where you can start to run into problems is when the engine doesn't develop enough power for the given pump/cylinder combo. If this happens, then engine runs slower still....and usually puts out even less power, so a downward spiral starts - until the engine stalls or you reverse the splitter and let everything catch up.

If you are happy with the speed and power of the splitter, you can run the engine at what ever speed you feel suitable. Most splitters target 3600 rpm as this is what most small engines are governed to and where they make the most power.
 
M

MasterMech

Guest
One man show, half throttle or whatever is comfortable. Two or more ppl on the team, wide open.>>

Half throttle saves me a lot of fuel when working solo.
 

TreePointer

Minister of Fire
Sep 22, 2010
3,122
PA
I like the idea of saving fuel and decreasing noise, but I'm going to insert a word of CAUTION in this discussion.

My understanding is that these newer engines are designed to run at full throttle to ensure proper lubrication and cooling. That's why I run my splitter at full throttle.
 

velvetfoot

Minister of Fire
Dec 5, 2005
10,066
Sand Lake, NY
I run my 9hp Robin on the 30 ton HF splitter at half throttle all the time. I think it saves fuel and is quieter. I don't move that fast.
 

Jags

Moderate Moderator
Staff member
Aug 2, 2006
18,259
Northern IL
Just to clarify - running the engine slower will not DECREASE pressure until you get to the point that the engine will not pull the pump (load) . It WILL decrease flow, which will slow down the speed of the ram. If you have an engine/pump combo that the engine will bypass the pressure relief valve at half throttle - you have all the working pressure that the machine can produce but at a decreased rate of flow.
 
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