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OT - logsplitter motor/pump size

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  • OT - logsplitter motor/pump size

    I have an old home built logsplitter (built by someone else). Currently the logsplitter has a 5 hp Briggs motor and single stage pump. Pump works well but has begun leaking. I am looking to replace the pump with a two stage pump. I also have access to a newish 8 hp motor (Tecumseh) formerly on a snowblower (no aircleaner). I would need to fab up some sort of an air cleaner. Tecumseh also has 110v electric start - convenient fro my wife who has gravitated to log splitting provided I pre-split logs to heavy for her to handle.

    Looking at replacement pumps, both the pump rated for 5 hp and the pump rated for 8 hp (they also make a pump rated for 6.5 hp) put out 3000 psi. I understand that the increase in pump volume will increase the speed of the piston travel (4 inch dia bore). I do not intend to replace the cylinder. How much of a performance benefit will I notice with the 8 hp vs the current 5 hp? Will the 8 hp pump give a bit of an impact effect if the rod/wedge is traveling faster?
    Metro Detroit

  • #2
    8/5 or 1.6 faster approx.

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    • #3
      I guess my question is - is there any other performance increase other than unloaded piston rod stroke speed?
      Metro Detroit

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      • #4
        The cycle time desired will determine the pump volume and power requirements, most hydraulic pumps easily available to consumers have a fixed volume per revolution.
        For example a 1 cubic inch per revolution gear pump will displace 3000 cubic inches of oil when operated at 3000 RPM's by a small internal combustion engine.

        A 4" diameter hydraulic cylinder with a 36" stroke is 452 cubic inches of volume, 3000 cubic inches per minute divided by the cylinder volume in cubic inches = a 6.6 minute cycle time.

        Comment


        • #5
          You can get a double pump with a pressure relief valve that will give you speed unloaded and switch to the single pump for power within the engine limits.
          Helder Ferreira
          Setubal, Portugal

          Comment


          • #6
            Originally posted by Bented View Post
            The cycle time desired will determine the pump volume and power requirements, most hydraulic pumps easily available to consumers have a fixed volume per revolution.
            For example a 1 cubic inch per revolution gear pump will displace 3000 cubic inches of oil when operated at 3000 RPM's by a small internal combustion engine.

            A 4" diameter hydraulic cylinder with a 36" stroke is 452 cubic inches of volume, 3000 cubic inches per minute divided by the cylinder volume in cubic inches = a 6.6 minute cycle time.
            Double check that math.... I believe its 6.6 cycles PER minute ! Two stage pumps thicken the plot more calculating cycle times, the logs resistance to splitting will determine the pressure rise and this the point the pump switches stages. With no log it will stay in the high volume low pressure mode and cycle much faster. Either way, the two stage pump will give a much faster retract after the log is split due to the resistance being gone.

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            • #7
              This is why I like this forum, one can not get a joke past you lot (-:
              https://www.youtube.com/watch?v=ijiazWlawUY

              Comment


              • #8
                Originally posted by Bented View Post
                This is why I like this forum, one can not get a joke past you lot (-:
                https://www.youtube.com/watch?v=ijiazWlawUY
                So yer wrong, call it a joke then post a Music Video? Bented is a good definition JR
                My old yahoo group. Bridgeport Mill Group

                https://groups.yahoo.com/neo/groups/...port_mill/info

                Comment


                • #9
                  Sounds like "Alibi Ike"?

                  Comment


                  • #10
                    I also encourage people to quench metals using the tears of clowns, this is not a joke as it works a charm, clowns are evil (-:

                    As are penguins, they do not cry.
                    Last edited by Bented; 10-17-2020, 06:22 PM.

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                    • #11
                      I have a 5HP dual stage splitter, it will split anything I have and is faster than me.
                      I can check the pump size if you want.
                      Beaver County Alberta Canada

                      Comment


                      • #12
                        Originally posted by Noitoen View Post
                        You can get a double pump with a pressure relief valve that will give you speed unloaded and switch to the single pump for power within the engine limits.
                        Noitoen:
                        What you describe is what I understand is referred to as a two stage pump in North America. I intend to buy a two stage pump.
                        Metro Detroit

                        Comment


                        • #13
                          Originally posted by aribert View Post

                          Looking at replacement pumps, both the pump rated for 5 hp and the pump rated for 8 hp (they also make a pump rated for 6.5 hp) put out 3000 psi. I understand that the increase in pump volume will increase the speed of the piston travel (4 inch dia bore). I do not intend to replace the cylinder. How much of a performance benefit will I notice with the 8 hp vs the current 5 hp? Will the 8 hp pump give a bit of an impact effect if the rod/wedge is traveling faster?
                          When comparing single stage pumps with equal working pressure ratings, their performance comes down to the pump's output in gallons per minute at a specified rpm. If you have a pressure gauge on the piston side of the splitting cylinder you will note very little pressure required to move the rod without a load, and for most wood splitting there's not much pressure required to split the wood. It's only in the nastier stuff that the system is ever put to serious work. That's where the two stage pump becomes beneficial. High speed with little pressure for little load and high pressure at a lower flow when busting through the the nasty stuff. Here's a link to some formula to make some pump comparisons, and a link to some pumps:

                          https://northernhydraulics.net/catal...culations.html

                          https://northernhydraulics.net/catal...mps-388-1.html

                          I'm not endorsing anything shown here. Just offering up the information.

                          Comment


                          • #14
                            Originally posted by tom_d View Post

                            When comparing single stage pumps with equal working pressure ratings, their performance comes down to the pump's output in gallons per minute at a specified rpm. If you have a pressure gauge on the piston side of the splitting cylinder you will note very little pressure required to move the rod without a load, and for most wood splitting there's not much pressure required to split the wood. It's only in the nastier stuff that the system is ever put to serious work. That's where the two stage pump becomes beneficial. High speed with little pressure for little load and high pressure at a lower flow when busting through the the nasty stuff. Here's a link to some formula to make some pump comparisons, and a link to some pumps:

                            https://northernhydraulics.net/catal...culations.html

                            https://northernhydraulics.net/catal...mps-388-1.html

                            I'm not endorsing anything shown here. Just offering up the information.
                            +1
                            I used to have a splitter I built with a 2 stage pump, log lift powered by a true 5hp electric motor. I had the relief valve set at the pumps and cylinders rated pressure of 3000psi. It was a 4in bore cylinder which gave me a true 20 ton force. I had a pressure gauge on it and nearly all the wood split at 1500psi or less, all hardwoods. When the gauge started passing 2000 psi PAY ATTENTION!! sometimes the wood would split with near explosive force and go flying! That pressure gauge was the only indication of the force being generated, hydraulics are pretty silent and the extreme forces developed can go unnoticed UNTIL something bad happens ! A pressure gauge tells you when to start ducking or running ! LOL

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                            • #15
                              You can also get a swash plate controlled piston pump. It will adapt itself automatically to the power of the motor. In that way, speed will always be optimized in relation to the pressure needed to split different logs.

                              https://youtu.be/RjLaU8nFnzE
                              Last edited by Noitoen; 10-18-2020, 05:31 AM.
                              Helder Ferreira
                              Setubal, Portugal

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