2 stage pump question

[polemidis]

I am starting to play with a firewood processor design. After researching the forums , the net, and 9kproducts website, I saw processors with big gas engines, also some with 2 gas engines one for the splitter with a 2 stage pump, and one gas engine with a regular gear pump for the rest of the hydraylics.

My question is since I do not want to make 2 isolated circuits, is it possible to use a 2 stage pump for everything? (log advance, log clamp, chainsaw motor). I am not asking for the design, just if it is possible and reasonable.

More specific:
Start with a 16HP gas engine (I have it already here)
add this pump

I have a sence that this can be done with the use of a "flow control valve" somewhere on the circuit?

Thank you!

 

[MossRoad]

Not to answer your question about using one 2-stage pump for everything, but why don't you get a stackable pump and run one, two, or three pumps all of off one engine?

My "tractor" is all hydraulic. I have one Kohler Command 25hp gas engine. It has a variable volume pump on the front shaft of the engine for propulsion, and two, stacked pumps on the rear shaft of the engine for the main hydraulics for the mowers, trenchers, etc... and the FEL/steering.

Newer models of this machine have the variable volume pump and the other two pumps all stacked in a row off of just one side of the motor.

Anyhow, that would allow you a two-stage pump for the hydraulic ram and a dedicated single speed pump for the other functions, and possibly a third pump for the chainsaw, etc... all off of one engine shaft.

 

[polemidis]

Not to answer your question about using one 2-stage pump for everything, but why don't you get a stackable pump and run one, two, or three pumps all of off one engine?

My "tractor" is all hydraulic. I have one Kohler Command 25hp gas engine. It has a variable volume pump on the front shaft of the engine for propulsion, and two, stacked pumps on the rear shaft of the engine for the main hydraulics for the mowers, trenchers, etc... and the FEL/steering.

Newer models of this machine have the variable volume pump and the other two pumps all stacked in a row off of just one side of the motor.

Anyhow, that would allow you a two-stage pump for the hydraulic ram and a dedicated single speed pump for the other functions, and possibly a third pump for the chainsaw, etc... all off of one engine shaft.

I will look at it, didn;t know that possibility. But I cannot find any "stackable" pumps at surpluscenter.com Can you give me link plz, I only find stackable valves!:confused2:

EDIT: If I am correct I found some on surpluscenter that are called "multi-section" pumps, but their cost is 4 times the "normal" pump! baileyshydraulics do not have them at all, so it looks like thats a dead end for me

 

[LD1]

There is a reason commercial ones use two pumps.

2-stage pumps shift from high to low based on the pressure demands of the system.

The splitter ram is the biggest cylinder in the system, and thus the slowest. So you want the high speed when its retracting....or when its extending but prior to making contact with wood/wedge.

With a processor, its like a backhoe. You are running multiple functions at the same time. IE: you may be lifting the log lifter , running the saw, and retracting the ram all at the same time.

Doing so will likely cause the pump to shift into high pressure / low speed mode.....which will slow the ram down dramatically and you will be waiting on something constantly.

AND, typically two stage pumps dont work well with motors.

 

[polemidis]

ok, got it. So, going for 2 circuits then. One with for the splitter with 2-stage pump, one for the rest of the stuff. Thank you

 

[oldnslo]

My question is since I do not want to make 2 isolated circuits, is it possible to use a 2 stage pump for everything? (log advance, log clamp, chainsaw motor). I am not asking for the design, just if it is possible and reasonable.

More specific:
Start with a 16HP gas engine (I have it already here)
add this pump

I have a sence that this can be done with the use of a "flow control valve" somewhere on the circuit?

Thank you!

Simple answer is yes you could use a hi-lo pump and flow control but it would be very inefficient and slow since there is no feathering from hi flow to low flow.

You would also lose approx 1/3 of your pressure for work since you would have to keep the pump locked in lo flow which requires keeping it above the shift pressure.

Running double or triple pumps will provide a better functioning system.

 

[MossRoad]

Prince makes them. SPD2 series.

I'm not sure who makes the ones on the PowerTrac machines.

Depending on your engine, you can get a front drive shaft for about $45 and drive a pump on the front as well as the back.

 

[polemidis]

Prince makes them. SPD2 series.

I'm not sure who makes the ones on the PowerTrac machines.

Depending on your engine, you can get a front drive shaft for about $45 and drive a pump on the front as well as the back.

Prince SPD2 costs $430+. Too much. It will cost a lot less with a 2nd engine design. For the splitter I can use a cheap engine, I think 12hp is more than enough.

 

[LD1]

Prince SPD2 costs $430+. Too much. It will cost a lot less with a 2nd engine design. For the splitter I can use a cheap engine, I think 12hp is more than enough.

Dont screw around with "thinking" when it comes to this.

Size it right.

Decide what pump you want. Size the motor accordingly. If you go too small, its going to stall before reaching max pressure. Go too big and you are just wasting money and fuel.

 

[polemidis]

Dont screw around with "thinking" when it comes to this.

Size it right.

Decide what pump you want. Size the motor accordingly. If you go too small, its going to stall before reaching max pressure. Go too big and you are just wasting money and fuel.

I agree, absolutely. By saying 12hp, (and with the correct size of pump. 22 GPM Dynamic 2-Stage Pump | 2 Stage (Log Splitter) Pumps | Hydraulic Pumps | Hydraulics | www.surpluscenter.com) I mean that it is enough for a log splitter for my needs