Log Splitter Pump question!

[michigander II]

I am thinking about building a log splitter. I wanted to get about a 8 HP motor and match it up to a 16 gpm pump. Is there a difference or advantage to getting a two stage pump? I know of a "truck" PTO pump that is 16 gpm, but not a two stage. Would this be a better pump for a splitter? And could the 8 HP motor handle this pump? It should have better cycle times than a two stage pump, right? Thanks for your replies!

 

[RonMar]

Yes, a two stage pump configured for a logsplitter with the correct pressure relief/cutover valve should give faster cycle times. Both pump bodies work in parallel for high volume/low pressure operation. As soon as a load is encountered such as when the ram contacts the log, a pressure sensing valve shifts the pump from parallel to series operation where both pumps are in line for high pressure low volume operation. As soon as the load pressure drops below the valve setpoint such as when the log finally pops/splits opr you retract the ram, then it shifts back to parallel/high speed ops.

I have never owned a logsplitter and do all my splitting by hand, but I have worked a few over the years. some were better than others, but the larger HP ones sure had an easier life. Depending on the type of wood and frequency of use, 8HP may work OK, but if used hard on hard splitting wood, you may be working the engine pretty hard which will shorten it's life. 10HP may be a bit more expensive, but if you maintain it properly, it will not be worked as hard and the likleyhood of you having to replace it due to overwork is less.

 

[mopacman]

I have a single stage pump on my spliter and it runs slow. If I do it again I will use a 2 stage pump for speed. A 2 stage pump is 2 pumps in one. with no load the ram runs fast up to the log, than one stage quits so the engine has enough power to pump up the pressure to split the log. an 8 hp motor is a good size to use and a 2 stage pump sized for 8hp will give give the best cycle time.

 

[michigander II]

Mopacman, Is your single stage pump 16 gpm? I thought if the first stage on a two stage pump is somewhere around 12gpm with 750 #s pressure, then the second stage kicks in which is about 2000 #s pressure but gpm goes down to 4 gallons about. Am I wrong to think a 16 gpm single stage wont work? Or just does it need more than the recommended 8HP engine?

 

[SPYDERLK]

I am thinking about building a log splitter. I wanted to get about a 8 HP motor and match it up to a 16 gpm pump. Is there a difference or advantage to getting a two stage pump? I know of a "truck" PTO pump that is 16 gpm, but not a two stage. Would this be a better pump for a splitter? And could the 8 HP motor handle this pump? It should have better cycle times than a two stage pump, right? Thanks for your replies!

What everybody said is right, but may not click in without some background. Approximate HP requirements will be GPM x PSI/1714. That would be about 25HP for 16GPM at 2500psi. The 8HP would not drive that pump to give a high enuf pressure for tough stuff unless you geared it down about 3 to 1. That would reduce the delivery rate to 5gpm tho, and you dont want that cuz it would be slow. The same effect as the geardown could be achieved by tripling cylinder area but would have the same slodown effect because more fluid would have to be pumped even tho at proportionally lower pressure.

Your 8HP will drive a 10GPM two stage pump tho, giving good speed on a 4" cylinder up until significant resistance is encountered, then slow advance thru the tough parts as the pump automatically reconfigures for hi pressure at a reduced delivery rate. This only happens on the tough stuff. Many logs split at the lower pressure, the pump not reaching the shift point and therefore staying in its high delivery mode.
larry

 

[michigander II]

Spyderlk, Thanks for your answer! I was thinking that it would take more than a 8 hp engine to run this pump. I just wanted to make sure.

 

[Mickey_Fx]

Here is an alt to the typ hyd splitter. Very low cost in comparison.

The Stickler - The Most Efficient Log Splitter Ever Designed

 

[jimmysisson]

Spyderlk, Thanks for your answer! I was thinking that it would take more than a 8 hp engine to run this pump. I just wanted to make sure.

For reference, I have a homemade splitter with B/S 7 hp engine and a Barnes 13 gpm 2-stage pump. It's about the right size for the engine, about all the pump that 7 hp can handle, I'd say. Spends most of its time in high speed. For some reason, it pushes the 4" cylinder mighty slow even with no wood on the table, about 18 sec. out and 15 sec. in. I've tried lots of things to speed up the operation, because it's borrrrring. I guess as I get older it'll seem about right. I have a 36" cylinder but set up stops so I can adjust the return length to the length wood on the table.
Jim

 

[SPYDERLK]

For reference, I have a homemade splitter with B/S 7 hp engine and a Barnes 13 gpm 2-stage pump. It's about the right size for the engine, about all the pump that 7 hp can handle, I'd say. Spends most of its time in high speed. For some reason, it pushes the 4" cylinder mighty slow even with no wood on the table, about 18 sec. out and 15 sec. in. I've tried lots of things to speed up the operation, because it's borrrrring. I guess as I get older it'll seem about right. I have a 36" cylinder but set up stops so I can adjust the return length to the length wood on the table.
Jim

Check your pump. Your cylinder should moveabout 5" per second at 13gpm. May be stuck on slow or doesnt completely shift to fast mode. Does the engine run easy as the ram moves toward the log?
larry

 

[jimmysisson]

Yep, runs easy, and hunkers in for the work when it shifts into low. Given that it's slow out and back, doesn't seem like a valve problem (been like this since valves were new). Has full power in a difficult split, I'd say. Ran it earlier with an 11 gpm pump (13 was in hope for more speed) and it was slower but about the same power. I've about given up on this speed problem. By calculation, this thing ought to cycle in about 13 seconds for both directions.
I don't want to steal this guy's thread. Maybe I'll post this on its own, though I did a couple of times last winter and haven't made headway. I seem to be getting older fast these days, so maybe my splitter and I will reach an understanding.
Jim