Log Splitter Pump

[Kubota 2350]

I have a log splitter with a 6.5 Hp engine, it has a 11 GPM 2 stage pump on it that has gone bad.
If I were to replace the pump with a 13 GPM pump, would it speed up the movement of the cylinder, and would the engine be able to run the bigger pump?
Or should I just replace the pump with an 11 GPM pump?
The pumps are only $15.00 different, so if it'll work better I'd get the bigger one.

Thanks

 

[AKKAMAAN]

If I were to replace the pump with a 13 GPM pump, would it speed up the movement of the cylinder, and would the engine be able to run the bigger pump?

Haldex pump are flow rated at 3600rpm.
If your engine can run that pump will be a matter of the max pressure setting you will give the system, AND at what rpm your engine deliver max HP....so you can do the math your self, "13.1 GPM x (Actual rpm/3600) x PSI/1714 = HP"

Or should I just replace the pump with an 11 GPM pump?

I would go with the 13gpm pump....rule of thumb on two stage pump "flow rating/2=required HP", You might have to "tune the max pressure and the low pressure to make engine not bog down..."

The pumps are only $15.00 different, so if it'll work better I'd get the bigger one.

:thumbsup:

 

[J_J]

A 5 HP will run that pump, so a 6.5 will do fine. Yes, the increase flow will reduce the cycle time.

 

[AKKAMAAN]

"Math Class" :laughing:
Example for Haldex-Barnes 13GPM two-stage pump.

Displacement Analysis
Low gear 0.194 cui/r
High gear 0.194 + 0.647 = 0.841 cui/r

Flow Calculations
Conversion, 231 cui = 1 usg
High flow at 3600 rpm>> 3600*0.841/231= 13.1 gpm
Low flow at 3600 rpm >> 3600*0.194/231= 3.0 gpm

Power Calculations
Max prv setting = 3000 psi
Low pressure adjustable between 400 and 900 psi

Max Power at low flow/high pressure stage>> 3.0*3000/1714= 5.25 hp
Max power at high flow/low pressure stage>> 13.1*900/1714= 6.87 hp

Of course now, the higher number will be the power requirement for the engine

To make a 6.5 hp engine able to run this pump properly at above calculation, low pressure need to be decreased to>> 6.5*1714/13.1= 850 psi or lower

If engine power is rated at a lower rpm than 3600rpm, for example 3000rpm, that will effect the flow calculations and accordingly also the power calculations

To make this pump run with a, from J_J suggested, possible 5 hp engine, pressure need to be decreased accordingly.
at 3600rpm the pressure need to be 5*1714/13.1=654 psi for high flow stage
and 5*1714/3.02=2837 psi for low flow stage

Note: Always remember to recalculate flow, if engine is running other rpm's
Also these calculation are "best case scenario", and do not include mechanical friction losses in the pump, plus the fact that there is a by pass flow resistance (negligible), from the larger gear in the pump, when when running the low stage

Data source Haldex-Barnes pdf file

"over and out"

 

[LD1]

Yes it will make the cylinder run faster, but it might not be much of a noticable differences to you.

Currently, and 11gpm pump will give you an overal cylce time of 16.08 sec (assuming a 4.5" cylinder @24" long with a 2" rod). That is 8.94sec on the power stroke and 7.14 on the return.

If you wet with the 13 gpm, you would gain 1.38 seconds on the power stroke, and 1.10 sec on the return for an overall cycle of 13.60 seconds.

You have already been given good advice above, so only YOU can decide if this is enough speed increase to spend the extra $15, and maybe have to adjust the pressure on the low pressure side of the pump.

 

[Bikewanderer]

Yes it will make the cylinder run faster, but it might not be much of a noticable differences to you.

Currently, and 11gpm pump will give you an overal cylce time of 16.08 sec (assuming a 4.5" cylinder @24" long with a 2" rod). That is 8.94sec on the power stroke and 7.14 on the return.

If you wet with the 13 gpm, you would gain 1.38 seconds on the power stroke, and 1.10 sec on the return for an overall cycle of 13.60 seconds.

You have already been given good advice above, so only YOU can decide if this is enough speed increase to spend the extra $15, and maybe have to adjust the pressure on the low pressure side of the pump.

I would also do it - 13 gpm. You can modulate flow with the valve if necessary.

 

[Highbeam]

You should do it. 6.5 times 2 equals 13. Run the 13 for sure. If you had an 8HP engine then I would recommend the 16gpm pump. Most every modern small engine out there is made to run at 3600RPM which is no small coincidence is 60hertz which is the US's AC power frequency.

 

[AKKAMAAN]

You should do it. 6.5 times 2 equals 13. Run the 13 for sure. If you had an 8HP engine then I would recommend the 16gpm pump. Most every modern small engine out there is made to run at 3600RPM which is no small coincidence is 60hertz which is the US's AC power frequency.

Great point! Thanks!

 

[Denwa]

A 5 HP will run that pump, so a 6.5 will do fine. Yes, the increase flow will reduce the cycle time.

There may be some logic on the manufacturers side behind the pairing of pump and motor size. If a given combo will yield a given cycle time, said cycle time may be calculated with operator safety in mind.

One hopefully gains wisdom and judgment with experience. So, faster cycle times in a wood splitter might pose no long term problems for the average joe, but.... *MY* experiences when first using my first wood splitter led me to appreciate the fairly slow cycle time. You know, getting a finger out of the
way at the last second, having a piece of wood pop when it splits, having a
leg or foot between the wood being split and a hard thing.

As with tractors, lots of potential ways to maim yourself with a wood splitter, so having just a wee more time to get your parts out of the way, or see a bad outcome developing is not necessarily a bad thing.

Something to consider.

Dennis