Who know about hydraulics / power

[Justme]

I have a firewood processor that can be powered via an 11kw electric motor however it states the minimum pto to be 30kw.

Both turn the same 3 hydraulic pumps.
The elec motor directly at about 1500 rpm & the pto at 540 rpm but with a 3 to 1 gearbox to increase the rpm.

I wish to power this either directly from an engine with a 2 to 1 reduction or with a 5 or 6 to one reduction into the pto input.

How can the power needs be so different from pto to electric?

What will the minimum engine hp I can use?

 

[Justme]

Secondary question.

If I fit the 11kw (230 or 400v available) motor what size genny would it need?

I think 30 - 40hp.

 

[Barking Mat]

I used to run 2.0 litre diesels attached to hydraulic pumps, marine propulsion..

I would have thought 50 hp, would suffice?

But it's all about hydraulics... I would think the supply line pipes would be an indicator.

Be careful with high pressure hydraulics.

 

[8ob]

I have made up a couple of diesel powerpacks using 4 pot perkins engines, both were to free up tractors. One was running a Stenner bandmill and the other a log processor. You can buy off the shelf SAE bellhousings which will bolt up to any truck engine, they can be used to direct pto drive from or bolt hydraulic pumps too. The one that went on the log processor ran a small leccy alternator off the front and the engine driven compressor was connected to a tank, that proved handy for maintenance and the leccy was good for worklights. A fixed speed/governed stationary engine is better if you can get one, if not fit a speedic.

Bob

 

[Justme]

I used to run 2.0 litre diesels attached to hydraulic pumps, marine propulsion..

I would have thought 50 hp, would suffice?

But it's all about hydraulics... I would think the supply line pipes would be an indicator.

Be careful with high pressure hydraulics.

Seeing as my digger has three huge pumps & only 40hp I think the recommended PTO hp is far too high.

11kw is about 15hp so was hoping 22hp engine would be enough.

Two pumps have 3/4" lines & one 1/2"

 

[mike os]

3 to 1 gearbox, 3 to 1 power conversion

The additional power is to boost the rpm at the pump and gearbox speed conversion

 

[Justme]

3 to 1 gearbox, 3 to 1 power conversion

The additional power is to boost the rpm at the pump and gearbox speed conversion

So if I have this right you are saying that the 40hp in via the pto is reduced to 13.33hp at the pumps as the rpm has gone up?

With that in mind the 22hp motor I have been offered with a 2 to 1 reduction is quite close.

But I think better would be to direct mount 3 new pumps to the engine.

Then they are rated for the higher rpm.

 

[stormin]

3 to 1 gearbox, 3 to 1 power conversion

The additional power is to boost the rpm at the pump and gearbox speed conversion

All the gearbox is doing is increasing rpm, but reducing torque. The power loss should be less than 15%.
It's likely the torque requirement, where electric motors excel, that requires a large pto hp.

 

[mike os]

So if I have this right you are saying that the 40hp in via the pto is reduced to 13.33hp at the pumps as the rpm has gone up?

With that in mind the 22hp motor I have been offered with a 2 to 1 reduction is quite close.

But I think better would be to direct mount 3 new pumps to the engine.

Then they are rated for the higher rpm.

Pretty much... there are losses etc but really not worth worrying about

 

[8ob]

To step up or down or make electricity to drive a motor to drive a pump is just a stack up of operating losses. The log bench will have a flow requirement, match this with a pump that flows that amount directly off the back of an adequately sized stationary engine, job done.

Bob

 

[Justme]

To step up or down or make electricity to drive a motor to drive a pump is just a stack up of operating losses. The log bench will have a flow requirement, match this with a pump that flows that amount directly off the back of an adequately sized stationary engine, job done.

Bob

Thats my feeling two.

The processor has 3 pumps stacked up.

I need to get the part numbers of the existing pumps to find the spec & then see what pumps match that & what HP / rpm they need.

 

[stormin]

Can all three parts of the pump be under full load at the same time? How many services will be working together?

 

[500e]

Torque is a factor you can have lot of HP with little torque so the load drags down the RPM & it is a vicious circle

 

[frank horton]

would think only 2 processes at one time.....
that loks like a modern tractor....dont they come with a 2 speed pto.....
I know my 399 did.....540-1200 I think...been a while...
if the high speed is around 1200 I'd bet this would do......can always up the eng speed a bit.....
the pump will still work at a slightly slower speed and take a little longer to process the wood.....
it aint a race.....other wise it's all gonna get a bit silly and expencive.....

 

[Justme]

would think only 2 processes at one time.....
that loks like a modern tractor....dont they come with a 2 speed pto.....
I know my 399 did.....540-1200 I think...been a while...
if the high speed is around 1200 I'd bet this would do......can always up the eng speed a bit.....
the pump will still work at a slightly slower speed and take a little longer to process the wood.....
it aint a race.....other wise it's all gonna get a bit silly and expencive.....

I think you missed the point.

i want to get rid of the tractor & power from a smaller engine.

ps its 540 / 1000 rpm on tractors
pps it sort of is a race when you are processing for other people.

 

[Justme]

Can all three parts of the pump be under full load at the same time? How many services will be working together?

Not sure yet which pump powers which bits.

But this is a list of all the actions that I know about:-

Splitter ram
chainsaw motor
conveyor out motor
conveyor in motor
splitting knife lift / lower ram
sawdust extractor fan motor
log clamp ram

Conveyor out runs continuously
plus
You can split & cut (inc clamp ) at same time & they are the biggest users of flow & pressure.

Or split & conveyor in motor

 

[m_c]

Power specs will be as much to do with ensuring the tractor used is physically large enough, as it is the actual power needed.
Otherwise you'll have people trying to run it on sub 20hp tractors, which will probably be as light as the machine.

Also, you may find when supplied with an electric motor, different hydraulics are fitted.
With the addition of electricity, they may use some electrical interlocks which limit how much hydraulic power can be used, whereas with PTO driven you may be able to use more hydraulic power.

 

[DaveB]

The pto rating is probably engine peak power, but that will be at far higher revs than when the pto is active.

 

[Justme]

Power specs will be as much to do with ensuring the tractor used is physically large enough, as it is the actual power needed.
Otherwise you'll have people trying to run it on sub 20hp tractors, which will probably be as light as the machine.

Also, you may find when supplied with an electric motor, different hydraulics are fitted.
With the addition of electricity, they may use some electrical interlocks which limit how much hydraulic power can be used, whereas with PTO driven you may be able to use more hydraulic power.

They spec power for pto & for transporting ie tractor max.

The machine can stand on its own & weighs about 900kg.

As far as I can tell the elec motor is a bolt on direct to the existing pumps.
There are no electrical bits on this machine in either version.

 

[Justme]

The pto rating is probably engine peak power, but that will be at far higher revs than when the pto is active.

PTO speed always used to be a direct effect of engine speed.
Hence max power was always available.
Now some use a hydraulic motor so you can set the rpm of the pto but at lower engine rpm for low outputs / fuel efficiency.