Firewood processor project.

[muddstopper]

I looked for specs on several larger chainsaws, but these numbers I am posting belong to a 346xp husquvarna. Not the size saw I would model a hydchainsaw after. I chose to use this set of numbers simply because all the specs are not given on the larger size saws I looked at.
Power output 2.7 kW
Cylinder displacement 50.1 cm³
Maximum power speed 9600 rpm
Max engine/motor RPM 14100 rpm
Idling speed 2700 rpm
Torque, max. 3 Nm
Torque, max. at rpm 7000 rpm
Clutch engagement speed (±120) 3800 rpm
Fuel consumption 494 g/kWh
Fuel consumption 1.35 kg/h
Spark plug Champion RCJ7Y, NGK BPMR7A
Electrode gap 0.5 mm
Ignition module air gap 0.3 mm
Oil pump type Automatic
Oil pump capacity Max 12 ml/min
Oil pump capacity Min 5 ml/min
Equipment
Recommended bar length, max 20 in
Recommended bar length, min 13 in
Chain speed at max power 18.5 m/s
Chain speed at 133% of maximum engine power speed 24.6 m/s

What I want to point out is the max engine rpms,@14100rpms, the maximum power rpms,@9600rpms and the max torque rpms @7000rpms. Max torque is at almost exactly half of the maximum engine speed. This is the reason thinking in terms of engine rpms when trying to build a hydraulic chainsaw is useless. Now look at the chain speed of 18.5ms. @ 9600rpm max power. This is the number you are shooting for when trying to match the gas engine to the hydraulic motor. Max torque is 3nm that converts to 26.5500 in/lbs. or 2.2128 ft/lbs. Thats not a lot of power and is pretty easy to match up to with a hydraulic system. While for a firewood processor, the 346xp might not have the cutting power I would choose, but the principles are similar across all sizes of gas chain saws.

 

[Millet]

I study some specs on several large chainsaw too. In the following graphic I put 2 gas chainsaw, 3120hp husqvarna and ms 880 Shtil.
The other chainsaw are popular hydraulic motor found on many processor and 1 motor specs from a harvester. I calculated with the max RPM
and PSI from the manufacturer specs. After working on that I realize that the best motor would be a smaller cu-in but faster rpm and higher PSI
So I "study" two motor for my project. PARKER 0.58 cu and PARKER 0.7 cu. You can see them at the far right of the charts.
I also calculated what I called the Power/SPEED which is the Nm x chain meter per second. Because like you said all is related.

 

[Millet]

The parker f12-40 is found on many harvester head and his RPM is slow but have a very high torque...

 

[Millet]

Also maybe some of you can help me. Do you know where I can buy a conveyor belt drive pulley? something like this:





Or an alternative to drive a belt?

 

[muddstopper]

I study some specs on several large chainsaw too. In the following graphic I put 2 gas chainsaw, 3120hp husqvarna and ms 880 Shtil.
The other chainsaw are popular hydraulic motor found on many processor and 1 motor specs from a harvester. I calculated with the max RPM
and PSI from the manufacturer specs. After working on that I realize that the best motor would be a smaller cu-in but faster rpm and higher PSI
So I "study" two motor for my project. PARKER 0.58 cu and PARKER 0.7 cu. You can see them at the far right of the charts.
I also calculated what I called the Power/SPEED which is the Nm x chain meter per second. Because like you said all is related.

View attachment 594039

View attachment 594040

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View attachment 594043

View attachment 594045

View attachment 594046

View attachment 594047

Lot of good information in one place, but you failed to compare torque in relation to sprocket size. The torque numbers of the chainsaw as well as the hyd motor are rated at the shaft. The 3120 and 088 gas powered chainsaws are running 7pin sprockets and your .07cuin parker motor is running a 16pin sprocket. You will need over twice the torque with the .7 motor as the gas saws to equal the cutting power. The .7 motor I think I already said is the minimum size motor I would consider. Trying to go over the recommended psi could end pretty badly. There are also other type motors you havent considered. The f12-40 is a bent axis and takes 5000psi and over 60gpm to produce the speeds and torque advertised. Take a lot of engine hp to get that kind of flow and pressure. In the middle are the axial piston motors. Generally high speeds and decent torque. There isnt any substitution for cuin's

 

[polemidis]

Also maybe some of you can help me. Do you know where I can buy a conveyor belt drive pulley? something like this:

View attachment 594054

View attachment 594055

Or an alternative to drive a belt?

Home - PRC Industrial

 

[Millet]

Thanks, it was a lot of work. :reading:
I did not compare torque/sprocket size but compare torque/chain per second,
which is related to the rpm and teeth number. is not the same thing?

If you watch the fourth page you can see that the parker
motor have at least twice the torque compare to the 3120xp and 880 ms.

What I note is the longer the bar the higher the Torque and lower the RPM.
Example: With the same motor/rpm/torque they use
15 sprocket teeth for 24"bar and 13 teeth for 36"bar.

 

[muddstopper]

I am not exactly sure what or how you are compareing torque to chainspeed. From experience I know going to a longer bar will effect cutting speed. As will changing out chain pitch. It simply takes more power to pull the extra chain lenght. With a gas powered saw you will see a drop in rpms as cutting load increases, because the saw is already maxing out its available power. With hyd, as the power requirement increases so does the pressure, as long as you have the pump and engine combo to build the required pressure. For this reason the hyd saw will maintain chain speed better than the gas powered saw. Now if you are cuting 12in dia wood, you probably wont be able to tell any difference in cut speed between using a 24in or 36in bar because you wont be maxing out available power.

 

[Virx1]

I tried the first time today hydraulics and electrical work.
It's alive .

Halumasina vahekatsetus. - YouTube

 

[Virx1]

50% of the machine ready.
Need to make a tree feeder.

Homemade Firewood protcessor. - YouTube