(Another) Firewood processor - hydraulic questions

[kiotiken]

I know there have been a few threads already, but I have a few hydraulic questions. This will be my first hydraulic project and I really have no idea what I'm doing so I'm looking for guidance and validation that my creation wont simply self destruct.

I'm planning a processor that will use my Stihl 361 to cut, so that part isn't an issue. I am planning to build a splitter, a feeder and an conveyor. My plan is to use old tires for the feeder, cut the side walls off and join them together. That part of the feeder will be powered by one hydraulic motor and I'm planning on using a second identical motor for a top clamping roller. I plan on constructing the conveyor from scrap ski-doo tracks and if I can't find those, tires again joined together with angle iron.

I am planning to use 2 15hp engines for power. The first engine will be dedicated to the splitter and the second will run the conveyor and feeder motors.

Splitter: I'm planning to use the 2 stage, 28/7 GPM log splitter pump from the Surplus Center. The requirement is 16hp, but 15 will have to do. 28 GPM DYNAMIC 2-STAGE PUMP

The rest: I was planning on using a multi section pump with one pump powering the conveyor and the second powering the feed motors and ax height cylinder. Here is the one I was looking at: 1.29/0.69 cu in CASAPPA PLP20.20/20.11 DOUBLE PUMP

Some questions:

1) Can I use one reservoir with tees to feed both pumps or do I need to have two reservoirs?
2) Most of the multi section pumps seem to have a max speed of 3000 RPM while the standard for a gas engine is 3600 RPM. I want to directly connect the pump to the engine, how do you resolve this, is there another pump I should be looking at?
3) The pressure from the multi section pumps if far higher than the max cont. pressure listed on any of the hydraulic motors. Do I use a relief valve set at the proper operating pressure or is there a better solution?
4) I would like one circuit to run the two feeder motors (belt and upper roller). Can I use a tee to feed the two motors, returning to another tee?
5) I would like the splitter to have an auto cycle function. Preferably, I'd like to simply hit a button, but that might be cost prohibitive. What is the best way to achieve an auto cycle?
6) I need help sizing and selecting motors for the conveyor and feeders.

I probably have a bunch of other questions I'm forgetting at the moment but any help with these would be very much appreciated.

 

[J_J]

I know there have been a few threads already, but I have a few hydraulic questions. This will be my first hydraulic project and I really have no idea what I'm doing so I'm looking for guidance and validation that my creation wont simply self destruct.

I'm planning a processor that will use my Stihl 361 to cut, so that part isn't an issue. I am planning to build a splitter, a feeder and an conveyor. My plan is to use old tires for the feeder, cut the side walls off and join them together. That part of the feeder will be powered by one hydraulic motor and I'm planning on using a second identical motor for a top clamping roller. I plan on constructing the conveyor from scrap ski-doo tracks and if I can't find those, tires again joined together with angle iron.

I am planning to use 2 15hp engines for power. The first engine will be dedicated to the splitter and the second will run the conveyor and feeder motors.

Splitter: I'm planning to use the 2 stage, 28/7 GPM log splitter pump from the Surplus Center. The requirement is 16hp, but 15 will have to do. 28 GPM DYNAMIC 2-STAGE PUMP

The rest: I was planning on using a multi section pump with one pump powering the conveyor and the second powering the feed motors and ax height cylinder. Here is the one I was looking at: 1.29/0.69 cu in CASAPPA PLP20.20/20.11 DOUBLE PUMP

Some questions:

1) Can I use one reservoir with tees to feed both pumps or do I need to have two reservoirs?

Answer * Yes

2) Most of the multi section pumps seem to have a max speed of 3000 RPM while the standard for a gas engine is 3600 RPM. I want to directly connect the pump to the engine, how do you resolve this, is there another pump I should be looking at?

Answer * Run the engine at 3000 rpm.

3) The pressure from the multi section pumps if far higher than the max cont. pressure listed on any of the hydraulic motors. Do I use a relief valve set at the proper operating pressure or is there a better solution?

Answer * The pump can develop a certain pressure, but it is the hyd components that develops the pressure. You can install a relief on any component.

4) I would like one circuit to run the two feeder motors (belt and upper roller). Can I use a tee to feed the two motors, returning to another tee?

Answer * No, you need a divider circuit.

5) I would like the splitter to have an auto cycle function. Preferably, I'd like to simply hit a button, but that might be cost prohibitive. What is the best way to achieve an auto cycle?

Answer * Use Prince auto cycle valve or use a solenoid valve and switches to cycle the cyl.

6) I need help sizing and selecting motors for the conveyor and feeders.

Answer * Sizing hyd motors has to do with torque and speed. You will have to be the judge of that. We can tell you what size pump you need for the motors.

I probably have a bunch of other questions I'm forgetting at the moment but any help with these would be very much appreciated.

*******

 

[kiotiken]

Thanks J.J
I'm not clear on what you mean for #3, "The pump can develop a certain pressure, but it is the hyd components that develops the pressure. You can install a relief on any component." Does that mean that I need to install a relief valve in front of the motors to limit the 3000 PSI from the pump down to 1800 PSI, or whatever the motors max is?

I'd never heard of a divider circuit so I looked it up. It seems to simply evenly divide the flow from one circuit into two circuits. Do I need this to somehow prevent damage to the motors? The rubber feeder will provide a different amount of traction than the steel tooth roller clamping the top, and then there are knots in the wood, bends etc, so the motors being 100% in sync all the time probably doesn't matter anyway, I just don't want to destroy them.

As for the motors for both the feeders and the conveyor, I'm really confused about how to even start to size them. Here is the motor I was considering, it is one of the smaller motors listed on the SurplusCenter 2.5 cu in WHITE 255040F3DD22AAAA HYDRAULIC MOTOR. The problem is that it requires 12 GPM continuous flow for the specs. At 2000 PSI, a pump to drive only one of those motors would require 16 hp, or looking at it another way, at least 2 GPM more than my DK45 can supply through the remotes. That doesn't seem right at all. A small 5 hp gas motor would be able to drive a conveyor easily and I was assuming that 15 hp to drive 3 hydraulic motors would be about right. Even the smallest pump listed on the SurplusCenter site requires 4.5 GPM requiring 6 hp to drive a pump for that flow @ 2000 PSI.

 

[J_J]

I'm not clear on what you mean for #3, "The pump can develop a certain pressure, but it is the hyd components that develops the pressure. You can install a relief on any component." Does that mean that I need to install a relief valve in front of the motors to limit the 3000 PSI from the pump down to 1800 PSI, or whatever the motors max is?

Answer * It depends on how you install the motors. If you have 3000 psi and have two motors at 1500 psi, then you install them in series. Same volume will run through both motors.

If you have one pump with 3000 psi, and two motors at 3000 psi, then you install them in parrallel and the flow will divide between the two motors.

It is always a good idea to install a relief valve across each motor.

I'd never heard of a divider circuit so I looked it up. It seems to simply evenly divide the flow from one circuit into two circuits. Do I need this to somehow prevent damage to the motors? The rubber feeder will provide a different amount of traction than the steel tooth roller clamping the top, and then there are knots in the wood, bends etc, so the motors being 100% in sync all the time probably doesn't matter anyway, I just don't want to destroy them.

Answer * If you have equal motors and want to run them at the same speed then an equal divider valve will divide the flow equally for each motor. You can also install unequal flow valve if you want one motor to run faster than the other. There are valves to regulate the flow using a lever, so rpm can be from 0 rpm to max rpm.

As for the motors for both the feeders and the conveyor, I'm really confused about how to even start to size them. Here is the motor I was considering, it is one of the smaller motors listed on the SurplusCenter 2.5 cu in WHITE 255040F3DD22AAAA HYDRAULIC MOTOR. The problem is that it requires 12 GPM continuous flow for the specs. At 2000 PSI, a pump to drive only one of those motors would require 16 hp, or looking at it another way, at least 2 GPM more than my DK45 can supply through the remotes. That doesn't seem right at all. A small 5 hp gas motor would be able to drive a conveyor easily and I was assuming that 15 hp to drive 3 hydraulic motors would be about right. Even the smallest pump listed on the SurplusCenter site requires 4.5 GPM requiring 6 hp to drive a pump for that flow @ 2000 PSI.

Answer * Go to the Surplus web site and select Technical help, then select Hydraulics on left, then Calculators, then pump displacement & HP, and or Motor Speed & Torque. Plug in the numbers and that shold help you concerning HP, motor speed, and torque, etc.

http://www.surpluscenter.com/Tech-Help/Hydraulics/Calculators/Pump-Disp-HP/

 

[J_J]

You need to figure the HP necessary to run all hyd functions or all the hyd load associated with a particular engine.

For instance, you have three hyd motors that require 20 GPM and are rated at 3000 psi.

An engine to run this pump at full pressure and GPM for those motors would require about 41 HP.

So you can see why engineers get paid to figure these things out before manufacturing a product.

 

[CJONE]

You need to figure the HP necessary to run all hyd functions or all the hyd load associated with a particular engine.

For instance, you have three hyd motors that require 20 GPM and are rated at 3000 psi.

An engine to run this pump at full pressure and GPM for those motors would require about 41 HP.

So you can see why engineers get paid to figure these things out before manufacturing a product.

+1
That is actually the fun part of my job, the hard part is getting good information from the customer. Kioti Ken do yourself a favor and stay away from Casappa. Prince makes small multi circuit pumps that are reasonable along with Honor pumps. Also these are aluminum based units and are not very dirt tolerant. I use either Permco or Commercial for my mobile stuff. These 15 hp engines, are they gas, diesel and who makes them? You may be better going with a 22 Gpm pump depending on your Cylinder size. CJ

 

[muddstopper]

Let me make a suggestion about your hydraulic motor choice. That motor is going to run way, way, to fast for a conveyor if you feed it the max pressure and flow numbers it requires. I dont think you want or need a conveyor that turns 1116 rpms cont. The split wood would be launching off the end of the conveyor at that speed. I dont know the actual speed that a conveyor runs, but I think you need to revisit your math and come up with a smaller hyd motor and consider gearing and a flow control to reduce the speed.

Seems you are going to be using a gas powered chainsaw to cut block your wood. This will greatly reduce your hydraulics and hp requirements for the rest of the processor. Pretty much all you plan on running off the hydrauics are the splitter, the conveyor and feeder. The feeder will only be using hydraulic power for fractions of amount of time as you advance the log to be cut. I would use a double spool valve to operate the feeder and the conveyor. Your conveyor might slow slightly while you advance the log, but the delay will only be momentary and shouldnt effect the split wood being conveyed off the splitter. Use the auotcycle valve for the splitting function. You didnt say what size cylinder you plan on using for the splitter, but a dump valve on the return will speed up your cycle times. Engine hp needed will be determined by how many hydraulic functions you intend to operate at the same time. It is obvious that you intend to run the conveyor continuous, but I think you will find it doesnt take as much hydraulic flow or pressure as you think to make it work. Just because a hyd motor is rate for xgpm and xpsi, doesnt mean you will be operating that motor at its full capacity. As I already said, you dont need a conveyor running 1100rpms, unless your intentions are to launch the wood across your wood lot.

Your pump choice will only max out your engine hp when producing max pressure. Big cylinders make big tonnage even at low pressures. A small cylinder, might max out the hp of your engine and cause bogging at the start of the split, but as soon as the wood pops, pressure will drop and hp will not be an issue. Unless you are going with a 6in or larger cylinder, I think you might find the 22gpm 2 stage pump to be a better choice for you little engine and it frees up a little hp to run your conveyor. Yes 22gpm means slower cycle times than a 28gpm pump, but the autocycle valves are only rated for 25gpm and you dont really gain a lot of speed by going with the larger pump. You will make more heat with the larger pump. More heat means more oil capacity, larger hyd tank, maybe a cooler. Just something else for you to think about and plan for.

Once you detemine exactly what size hydraulic motors and the pump sizes to operate them, Look for a pump that produces those numbers at the rated rpms that your splitter pump runs at. Pumps are available that allow you to mount (piggyback) another pump to the back of the first pump. It could be possible that you could bolt both pumps together and direct mount straight to your engine. Both pumps will need their own suction ports at the tank, and my personal preference to also supply both pumps with their own return filters and ports back to tank. They can be tee'd together and just use one return filter and tank port if you choose to.

 

[oldnslo]

In an ideal world you would start by determining your torque & RPM requirements for the conveyor & feeder systems. Then use this information to select a motor size that provided the required torque & RPM. Then once the size and number of motors have been determined use this information to calculate the pump size required based on flow required, pressure required and prime mover RPM. The pump size ( flow & pressure) would then be used to calculate required input drive HP from the prime mover.

Now real life: I have a 15 HP motor and want to do.... What components do I need and make it work as inexpensively as possibly.

Not picking on you Kiotiken , just stating what ideal is Vs typical reality on most projects.

For your feeder I would suggest trying to get your drive RPM's the same for the belt and upper roller and connect two equal sized motors in series. This keeps the torque and speed on both feeds very similar.

 

[kiotiken]

This is all great info, thanks guys. I'm watching a ton of vids on YouTube and my design is changing (once again). I REALLY like this one and now think I'll base my design on it. https://www.youtube.com/watch?v=pmSS0SEoxXs

This design eliminates the conveyor all together and allows me to fill up my firewood bags easily. I also have a set of pallet forks (I bought them brand new) that my BIL kindly used on a skid steer rated over 5000 lbs and pulled the forks right off the frame. The frame will be a nice SSQA base and the forks are obviously perfect as loading forks.

So I have 3 options I'm thinking of.

1) Making one almost identical to what's in the video and using a PTO pump. I'm concerned the hydraulic over electric components will be cost prohibitive. I'm also thinking the hydraulic chainsaw will be a lot of work to build and get right.
2) Stick to using my saw and using the 15 hp engine to power the 2 stage pump for the splitter and my remotes for the rest.
3) Run the splitter and other hydraulics off my remotes and use my chain saw. This probably only offers around 8-10 GPM @ 2250 PSI.

I have several cylinders to use for this project so I'm thinking of eliminating the feeder system and simply making it a tilt system. After loading a log and clamping it (I would have a double clamping system) the deck would tilt, the log would roll on rollers until it hit a stop, the log would be clamped again and the saw would cut it off, repeat.

CJONE: The engine I'm thinking about is a cheap Chinese knock off gas engine. I have one on a water pump I've been using for years (only 5 hp) and one on my roto-tiller and they've both been flawless. For the limited hours I would use this per year, I think it would be fine and I could buy 4 of them for the cost of a Honda. If I use this motor and 28/7 GPM 2 stage pump, I will use a 5" cylinder. If I use a 21 GPM @ 2250 PSI PTO pump or run off the tractors hydraulics, I will use a 4" cylinder.

muddstopper: I will check the auto cycle valve and go down the the 22 GPM 2 stage pump if I go that way, thanks.

oldnslo: real life sucks, doesn't it! Ya, there's a fair amount of cheapness in my planning. I only burn about 12 face cord per year and a log truck delivers about 24 face cord per load which means I'm only cutting wood every 2 years. 24 face cord is still enough to be a PITA and make me look for easier ways to do things, but it doesn't make sense to spend $10K doing it.

 

[muddstopper]

After posting a while ago, I went and took a look at the conveyors I plan on using for my processor. One is 14ft and the other is 18ft, both belt drive. Both are powered by 3/4hp 1725rpm electric motors. Both have a pulley reduction belt drive of about 2:1 and then a gearbox. I dont have a clue as to what the gearing is in the gear boxes. Belt rollers are right at 12in dia. These conveyors came off a saw mill off bearing slaps, so should work fine for split wood. I have been thinking about just how fast should these conveyors run to off bear the split wood and decided anything faster than what the wood comes off the splitter would just be wasted speed. With that in mind, I figure my splitter extends around 24in in about 6 sec. This would equate to 1ft every 3sec or about 20ft per minute. My conveyor wheels are 12dia or right at 3ft travel per rev. 7rpms would be right at 21fpm. Since my splitter cyl still has to retract, a 7rpm speed would still be almost twice as fast as my splitter can produce the wood. The hyd. motor the op has chosen is rated at 1116rpms at 12gpm. Nothing says you have to run that motor at max rated speed. it will still run, albeit at a slower speed, if it is supplied with less oil flow. Less flow equates less hp needed to run a pump. If one takes that hyd motor, cuts the flow to say 4gpm, it should still run at about 3-400rpms. Using pulleys or gearing, or a gear box, he can reduce the speed even further. He could feasibly cut the oil flow down even further (smaller pump or use of a flow control) to get to the final numbers he is looking for in his conveyor speed. With proper gearing he would still maintain the torque needed to pull the conveyors and reduce the amount of hp required to run a hydraulic pump. I think the conveyor feed system would put minimal hp drain on his 15hp engine and he wouldnt need 2 engines to pull everything.