Correct me if I'm wrong, but..

[varmint]

I am in the dark here, but after watching several neighbors use gas engine powered hydraulic splitters, it seems to me that just setting your throttle where you want it and going at it, with a 13 hp engine, should work unless the cylinder or pump is crazy wrong sized. Maybe a cycle would take 4 seconds instead of 2, but unless you're splitting 8 cords of wood a season, why worry?

 

[J_J]

Single stage and two stage pumps will make a difference in speed.

A 13 HP engine can power a single stage pump at 6.5 GPM at 3000 psi

A 13 HP engine can power a two stage pump at 22 GPM at 650 psi, and 6.5 GPM at 3000 psi.

The two stage pump will usually have the faster cycle time.

 

[20HP2N]

I think what he's after is he's trying to use the kinetic energy from the flywheel to keep the pump turning with the engine at a slow speed, when the pressure rises,the torque requirements demanded by the pump rises and it slows the engine, the flywheel (through the sprague clutch) kicks in and uses the flywheels stored energy to keep turning the pump for the short time thats required. Your into a REALLY BIG CAN OF WORMS here..... yess... something to keep me up at night.... try this , it's a start Flywheel Effect or Polar Moment of Inertia - Engineers Edge if you float around in here you will find ALL KINDS of stuff. Jim

Aye! Right on the head.
I want to run the engine at a slower than WOT (maybe half?) speed, but still keep cylinder speed up.
I need to oversize the pump for the engine, it's just that I need to work out the torque values that the engine produces at around half speed, not full speed.

When you use the formula for engine torque, (I assume) it's only feasible when calculating the engine's full rpm.
If you try to calculate at a lower rpm, the (theoretical) torque value goes up.(which I think is wrong)

When you consider stationary engines, the horsepower and rpm's are lower, but the torque produced by the flywheel(s) is very great in comparison.
The splitter application is kind of ideal, because there is a fair bit of time for the operator to go pick up a piece of wood and load it, so the flywheel has time to pick up speed again.

Thanks so much for your help...

nnnggghh....maybe it is a big can of worms indeed, but I love a challenge ......

 

[20HP2N]

I am in the dark here, but after watching several neighbors use gas engine powered hydraulic splitters, it seems to me that just setting your throttle where you want it and going at it, with a 13 hp engine, should work unless the cylinder or pump is crazy wrong sized. Maybe a cycle would take 4 seconds instead of 2, but unless you're splitting 8 cords of wood a season, why worry?

Yeah, I work everyday and need to split in the evenings. I don't like hearing the engine flying away after hearing machinery whine all day. Sometimes I will split for an hour with a maul, just so I don't have to listen to it.
We burn 5 cords per year.

 

[20HP2N]

Single stage and two stage pumps will make a difference in speed.

A 13 HP engine can power a single stage pump at 6.5 GPM at 3000 psi

A 13 HP engine can power a two stage pump at 22 GPM at 650 psi, and 6.5 GPM at 3000 psi.

The two stage pump will usually have the faster cycle time.

Thanks. I have considered one of those, and may still go there.
I've also looked at a regenerative valve (Prince), which may not be as convenient as the 2 stage pump is automatic and the valve relies on manual input.
Still, those pumps are rated at 4000rpm+.
....would it be as simple as slowing the engine down and gearing the pump up to keep the same pump GPM?

 

[J_J]

That valve you mention, is a Prince LSR-3060. and uses low GPM and increases the GPM at low pressure for fact extend when the load factor is low.

If the cyl gets into a heavy load, you have to back off the fast extend and use it as a normal valve.

It can only be used on a single stage pump.

 

[20HP2N]

That valve you mention, is a Prince LSR-3060. and uses low GPM and increases the GPM at low pressure for fact extend when the load factor is low.

If the cyl gets into a heavy load, you have to back off the fast extend and use it as a normal valve.

It can only be used on a single stage pump.

Yep. ..so..... correct me if I'm wrong, but for arguments sake, I use the nominal formula of 1 horsepower @ 1gpm = 1500psi and come up with 13 hp = 13 gpm. The 13 gpm is @4000 rpm.

So now, I take a pump twice as large (26gpm@ 4000rpm) but I only spin it at 2000 rpm....I'm back to my 13gpm....So now I can run that monster pump with my 13 hp engine? .....It just doesn't seem right....""

 

[J_J]

You can run the pump up to a certain limit, and then it will stall the engine.

26 GPM at 3000 psi requires about 53 HP

13 GPM----------------------------- = 27 HP

6.5 GPM-----------------------------=13 HP

So, where are you going with all this.

 

[20HP2N]

You can run the pump up to a certain limit, and then it will stall the engine.

26 GPM at 3000 psi requires about 53 HP

13 GPM----------------------------- = 27 HP

6.5 GPM-----------------------------=13 HP

So, where are you going with all this.

???? Why do you keep asking me where I'm going with all this? Are you making fun of me?

 

[J_J]

No sir, not at all.

Just wondering why you don't want to use the engines potential and a matching pump to get the most out of the setup.

You can always reduce engine rpm and decrease response time.

If you don't want my help on any of this, I will vacate this thread.