Firewood Processor

[shanerr]

Need some assistance on the hydraulics for a firewood process that i am building. I have a 23hp kohler and 15 gpm hydraulic motor to run the chainsaw. I am not sure what size pump i need. The 23hp runs 3600 rpms and max throttle. Any help on the pump is a appreciated. Hydraulics is not my strong suit.

 

[Tractor Seabee]

I am no expert. Check out the guys at Surplus Center. There is an on-line catalog you can download. Their Tech depart is really good. Seems like most Hyd pumps and motors work at a lot lower RPM that that gas engine, probably need a gear reduction box or a pulley arrangement. Remember hyd pumps are positive displacement so you need a relief valve back to the sump set for the optimum pressure of your motor and line accessories. JJ our forum hyd expert always recommends SC in his posts. He will probably jump in here.

Ron

 

[shanerr]

Thanks Ron i reviewed the web site. I will be calling them tomorrow.

 

[johndeerkiwi]

I can assist, but need to know a bit more information.....is the chainsaw is the only item absorbing power from your engine during the cut cycle, and if it is not, what else are you using? ie are you going to have a hydraulic ram lowering the saw, or a manual system? Will you use the same pump to work the splitting ram by taking turns with the chainsaw?(with 23 horsepower, that is probably the best option). Are you talking American gallons or imperial? (I assume American?)

The maximum recommended horsepower for a .404 chain is 50 h.p, but 23h.p is still alot faster than your faithful huskey, or whatever!! A 23 hp saw (.404pitch) at recommended revs will cut a 9"dia log in just over 1 second (80 square inches a second)

Achieving the recommended chain speed, also depends on the sprocket. The minimum recommended .404 chain speed is 15 m/sec or 3,000 ft/min, and the maximum, (and recommended) speed is 40 m/sec or 8,000 ft/min.
The largests commonly available .404 sprocket, in New Zealand at least, is a #14 tooth, and to achieve the recommended speed (40m/sec or 8,000 ft/min, you need 8,352 rpm on the saw shaft.
This is too fast for a standard hydraulic motor, although you can buy bent axis motors that are purpose built for this rpm (parker f-11 & f-12 series), but they are quite expensive. So some use a standard gear pump at maximum revs, and put up with a slightly slower cut, or you can use a chain drive to the saw shaft to speed the saw shaft up, such as a small duplex chain.
All motors have a flow per revolution so you can easily do the maths to work out how fast the motor will go with a certain flow.
However, there there are some variables to work through, such as do you wish to direct drive the pump off the motor?

 

[shanerr]

the chainsaw and a small cylinder to use to clamp down on the log while cutting will be the only motor/cylinder i will be powering off the 23hp motor. I am setting up the saw to operate manually. I have a separate motor 18hp to power a 28gpm 2 stage to run a 5x36 cylinder to split the wood.

 

[J_J]

Your 23 HP engine can pump about 11 GPM at 3000 psi. Will pump 13.5 GPM at 2500 psi.

 

[shanerr]

Thanks J_J If i figure right i should get at least 15gpm at 2000psi correct?

 

[J_J]

I got 16.5 GPM at 2000 psi using the 23 HP.

To get 15 GPM from a 3600 rpm engine, you have to have a 1 cu in displacement pump.

So to pump those GPM's, 15 , at 3000, you need

You select a pump based on the GPM/cu in displacement, at a certain rpm.

Any pressure developed from the pump is based on the load which will produce pressure, and with a potential to go as high as pump pressure at say 3000 psi.

You can limit the pressure by adjusting the relief valve to say 2000 psi.

At that pressure, you will not be using the 23 HP, maybe 21 HP

The volume and pressure potential will be based on the pump you have.

Do you have the pump now, and if so, I can tell you the HP required to turn the pump at a certain pressure ..

This pump is .98 cu in, and can develop pressure up to 2900 continious, and a 3000 rpm limit


SPECIFICATIONS
0.98 cu in dia
2900 PSI cont
3625 PSI int
3000 RPM max
5.7 GPM @ 1500 RPM
11.9 GPM @ 3000 RPM

 

[muddstopper]

I will point you to this thread on the forestry forum, I hope this is allowed, if not I guess the moderators will delete the link. http://www.forestryforum.com/board/index.php/topic,61961.0.html

Jdeerekiwi has given some good info already, I would give CRD metalworks a call and talk to their engineers. They will give you some good advise and can sell you the parts you need, including saw motor, sprockets, bars and chains.

A word of warning about purchaseing your saw motor, I havent found a decent motor for this purpose on the Surplus center site, even tho they do sell a lot of motors for this purpose. Will they work, yes, but do you want something that will work and eventually get the job done?, or do the work in a safe and efficient manner. Just because it will do the job, doesnt mean its the right tool for the job. The parker f11 and f12 motors will do the job very well, but you will find that a new motor will cost you several thousand $$$. The cheap small high speed motors, like are found on the surplus center site, will work, but dont have the power you need to be efficient. A compromise has to be made based on how much you can justify spending, and how much time you are willing to dedicate to getting the job done. This will most likely mean using a larger hydraulic gear motor with more torque and less speed than what you really want. Options to increase the speed of the saw chain are to use a high torque, low speed gear pump and drive the saw thru a jackshaft and pulley system. Which is what i am planning with my processor build. This isnt as simple as just mounting a shaft in some pillowblock type bearing. and throwing on different size pullies. Most pillow block bearing are only designed to run a few thousand rpms. Special high speed bearings that will withstand the 6-8000rpm desired speed are pretty costly. They also require a better lubrication system than just a few pumps of grease from a grease gun.

Another word on sprocket size. You can get all kinds of different size sprockets with different numbers of teeth or pins for pulling the saw chain. Size your sprocket to your saw bar. To large a sprocket to try to increase the chain speed will lift the chain out of the rails of the bar and cause excessive wear on your chain and sprocket, to small a sprocket will put unnecessary wear on the bar and chain.

 

[wdchyd]

Need some assistance on the hydraulics for a firewood process that i am building. I have a 23hp kohler and 15 gpm hydraulic motor to run the chainsaw. I am not sure what size pump i need. The 23hp runs 3600 rpms and max throttle. Any help on the pump is a appreciated. Hydraulics is not my strong suit.

Depending on how many functions you wish to do at the same time, you may consider getting a pump with multiple sections to allow hyd circuits to act independ of each other.....I've seen many firewood processors with 2, 3 & 4 sections

 

[johndeerkiwi]

Wdchyd is correct, the multi section pumps are effectively two separate pumps in one housing with a common drive-shaft, and make working two things at once much easier to hook up.
I haven't checked JJ's maths but I'm sure he knows his stuff so he has answered some of your questions for you.

You want to hydraulically clamp while the saw is cutting? That can be achievable with one pump. Some processors use a sequence valve which will direct all the oil to the clamp first, until the sequence valve's set pressure is achieved, and then the oil gets directed to the saw motor as well.This makes sure the wood is fully clamped BEFORE the saw starts. The clamp will however develop the same high pressure as your saw motor during the most demanding part of the cut, so you may need to limit this pressure.
I can think of 3 ways to do that...

1)fit a (normally open) pressure reducing valve to the clamp...when the set pressure is reached it closes, limiting the pressure in the clamp ram, to the set pressure.The oil then just runs on past on it's way to the saw motor.

2) use a small diameter ram on the clamp with not much leverage over the clamp, so even under full pressure from the saw, it's not enough to crush or bend anything.(Because the saw motor is connected to the same circuit, the relief valve will not go off, as the oil will flow on through the saw motor). In this set-up, the clamp pressure will vary during the cut depending on the load on the saw, and this could move the wood slightly. Also the clamp pressure might not be very high until the saw comes under load, so this is perhaps not the best option, but I have heard of it being done.

3) Arrange a spring system so that the clamp ram is pushing(or pulling) on (or against) a spring, thereby limiting the clamp pressure.

This formulas might assist:-
H.P. to drive a pump:- H.P.= (flow, Gallons per min x pressure, psi) divided by1714

You can see that the power consumed is a product of both the FLOW and the PRESSURE. Use this formula to establish if a given flow and pressure is ok with your motor, or use it to establish what pressure you can achieve with your motor at a given flow. The flow is always a result of the pumps flow per revolution x the revolutions, ie a 1 cu inch/ rev pump will pump 3500 cu inches @ 3500 RPM
Your motor will probably drop revs a little under load so I would work on about 3500 RPM at full throttle or less. These revs are getting up there (for a pump) but should be Ok with a small pump(check the maximum revs for your intended pump). If you motor exceeds the recommended RPM, or you wish to use a larger displacement pump at slower revs, you might have to use a vee belt drive, and drive the pump slower.
Keep us posted on your progress, and good luck!

P.S we use metrics in New Zealand so I use a metric formula.... H.P. = (litres/min x bar) divided by 600 = Kw (1 H.P. = 3/4 Kw) (PSI divided by14.5 = BAR)
1 U.S. gallon = 3.785 litres

 

[glastron23]

i think you should be looking for one of these motors Parker F11 we used a triple pump, one for the saw, one for the splitter and one for the other cylinders. we run 2 -10Gpm and 1 5 Gpm pump.. yes could use more on the saw but unless you are doing this for a living you can keep 2 people busy removing the wood from the knife.. if i was to do it over i would be looking at a closed flow/pressure compensated piston pump, yes a little more money but worth it with small HP engines. I would also be looking at a diesel instead of gas, much more fuel friendly and more torque. Jim

 

[Scooby074]

Turning my splitter into a processor is a future plan of mine. I was considering the parker f11. What kind of cost are they?

Something else I was considering was going direct drive and bypassing the hydraulic saw entirely. There are several direct drive processors out there that run the saw via a belt drive off a gas engine. Only thing there is they have an electric clutch to engage and disenage the saw. You'd think you would go through a lot of expensive clutches considering how many times the saw would stop and start.

 

[johndeerkiwi]

Some random thoughts.... Scooby, not much point telling you what f11 motors cost here,as we are down under,why not ring your nearest Parker dealer for a quote. They also have the advantage of being available with the saw bar attachment already built into the motor housing, just bolt on the bar! Our price (for a f11) was about 3 times the price of a cassapa gear motor and put us off the idea. I've had one a cassappa driving my small wood splitter for years(commercially).So we have decided to use a cassapa motor, and drive the saw with a duplex chain drive thereby increasing the revs.
However, we looked hard at direct drive options too, on the basis it HAD to stop between cuts.
Our conclusion was that a belt drive system will work, especially in a non-commercial processor, but with these provisos...
1) We wanted to cut large dia logs at speed (50 H.P), the belts would work fine, but not for the 50 H.P. we wanted to use! Up to about 15 or 20 H.P.maybe?
2 The tightening the belt method works ok for a clutch (remember the saw isn't starting under load), but because the belt slips the smallest pulley first, the belt clutch is better suited to where both pulleys are similar sized, or where the driving pulley is the smallest of the two, and usually on a saw it's the other way around. But yes it can be configured.
3) By putting a steel keeper around and just outside the driving pulley, the belt when loosened conforms to that shape, holding it just off the pulley. ie less scuffing or rubbing when in neutral.
4) We used a belt clutch on a post driver in a similar high work rate application....gave it arse-holes!.....Gates make slightly harder belts that don't "grab" like for example, mitsibushi belts, and consequently Gates belts were the only belts we found would slip in neutral, and they dont get as hot and last many times longer.(yea, buy American!) (and no, I dont have shares in Gates lol)

We looked at electric clutches too (like in air con units in a car, and once again 50 H.P. was too much but 10 or 15hp was ok.You can get info on electric clutches off the agents.
Another interesting method of driving a saw spindle is to use a friction drive. I have done tests on this and while (once again) 50 H.P. was not possible in our tests, a tyre running against a 4" flat pulley will however, run a saw. Unfortunately at the moment, I cant put my hands on the ft/lbs torque delivered this way, but if anyone is interested I have it somewhere in my mad scientist notebook.(laughs out loud)

 

[Scooby074]

Thanks Kiwi. Since I posted that, I got looking for prices on the f11.. $2-3000 Not unexpected, but that puts the f11 out of my budget for my build.

Some form of direct drive is in the plans for me., just to keep the costs down.

 

[muddstopper]

Johndeerkiwi, I noticed you said you where going to use a chain drive to gear up to the saw speed you are looking for. Just what kind of rpms are to trying to achieve? And What kind of bearing are you going to be using for the high speed shaft that results from this kind of setup. Normal pillow block type bearing are not rated for high rpms. Have you looked into the capacity of the bearings you plan to use.

As for an electric clutch setup to run a direct drive saw, I assume scooby is refering to using a gas engine, Here is a Number you can call to help with yor clutch decisions, Warner Electric, 815 389 3771. Just tell them what kind of Hp and rpms you intend to run the clutch and they can fix you up with a multiple belt drive electric clutch for around $300 +/-. Running 50hp isnt a problem for electric clutches, but their cost might be.

 

[johndeerkiwi]

Hi Mudstopper, we want to achieve close to the recommeneded chain speed which for .404 chain is about 40 meters/sec or for you fellas about 8,000 feet/minute.I have spotted a duplex chain I intend to use which from the motor to the chainsaw shaft that is not too heavy, as weight is the issue at high speed/small dia pulleys, as the centrifugal force wants to throw the chain out, so a lighter chain like a duplex(a double chain) is best.

I have spoken to my local bearing supplier who has given me the details of a pillow block bearing that they believe will handle the 8350 RPM that we hope to achieve. Mail me if you want the details. Although only rated to 6,000 continuous, bear in mind that the running is intermittent, and that exceeding the specs doesn't result in the world ending, more likely it reduces the expected life of the bearing from about 10,000 hours to 7 or 8,000 hours. They are grease-able bearings too, but don't need greased very often. I only use Castrol LMX grease now after we did some (unscientific) testing on different greases.

I am not having any electrics at all on my processor, and am doing a position auto retract on the main splitting ram based on mechanical triggering of the valve, as our oil flow and ram speed is quite fast so position retract and position stop will save the ram from thudding against the stops.
Cheers Johndeerkiwi

 

[Scooby074]

Has anyone considered a saw blade vs a chainsaw?

In what little research Ive done so far, sawblades seem to be winning in speed of cut and low maintenance fronts. Ive seen people who claim 50+ cord (actual number escapes me) before sharpening.

muddstopper, yes Im considering a gas engine to drive both the saw and the splitter. I think it was Hudson Badger who's design I was getting inspired by

 

[johndeerkiwi]

I looked at that, because at first I could see that a circular saw could be easily driven by direct shaft drive. But as we get quite a lot of larger logs(over 20") and have only 65 H.P available, I have decided to use a chainsaw.
There's no doubt the circular is less maintenenance, no chain oil and quick.

 

[muddstopper]

I too have looked at the circular blades. They are plenty expensive and take tons of oil to work well. They do last longer between sharpenings, but require a professional to keep sharp and true. Another drawback is size. To cut 24in dia wood, you would need a 52in dia blade. A lot of my wood is bigger than 24in dia, which would mean a even bigger blade. Economics sort of dictated to me to go with the .404 chain and bar. Simply put, I cant afford the expense since I dont do commercial firewood.