New Home Built Electric and Gas Splitter Project

[nvrs]

My application will be as follows:

Piggyback splitter unit that will be hanging off the back of my wood trailer via 2 receiver style hitches(or ramp with ball mount and tie down points, although I do have a truck crane in the trailer). It will not be that huge and will have to be fairly light weight(3-600lbs max). It must be no longer than 6' long(with tables collapsed) and a horizontal only design.

The power supply will be electric at first with a 2hp(110V x 30A) motor and a 11 gpm pump and a gas engine(specs anyone? not sure what to run here) to follow later(thanks to rx7145 for putting that idea in my head... ).

What rpm is needed for the electric motor? There are 1725-50 and 3450 rpm available.

Since the search button is broken and Google hasn't come up with anything other than 8" h beam, I am asking the crowd here what type of beam they use.

My welder buddy was thinking of using a 4x4 or 5x5 structural steel box with a 3/16" wall. On top of the box would sit a 7-8"x3/16" plate similar to other peoples designs that has been welded on. I also thought I might be able to use the inside of this beam for part of the fluid tank.

 

[CJ1]

You want to have 3400 rpm, dual stage pumps are designed to at 3600 what a gas engine is governed at. As far as a 30 amp 120v circuit are you going to have 1 installed, standard is 20 and 15 amps. CJ

 

[nvrs]

You want to have 3400 rpm, dual stage pumps are designed to at 3600 what a gas engine is governed at. As far as a 30 amp 120v circuit are you going to have 1 installed, standard is 20 and 15 amps. CJ

Thanks for the info, that puts that question to rest... Now to find the correct motor at the cheapest price...

I actually have 220v 30 amp line we used to use for an air conditioner that I will be using for the splitter at my house(it does need to be extended about another 45 feet). My dad only has 110v in his shop so I am trying to figure out some way that I can run it here and he can run it there.

If necessary I will rewire my house to a 20 amp 110v service to accommodate but I would rather run it on 220. Once I get a motor, I will try and come up with some sort of solution.

 

[kevin j]

There was a thread here a couple years back where a guy put an electric motor and pump in parallel with gas engine and pump. Both ran through check valves, into a common line to the spool valve and cylinder. The problem he had was I think check valves too small, but the concept is valid and common. They were intended to run one or the other, not both.

I am not an electrical expert, and don't play one on TV, but I think you want a 1750 motor, not a 3450, if you want any hope of running on 120 vac.

A 'nominal' 11 gpm pump is rated at 3600 rpm. Running a roughly 3600 rpm electric motor means 11 gpm, but it will take 5 to 6 hp to do that. A 5 hp electric motor can be overloaded easily, but the amp draw is still 5 or 6 hp. You won't get there on 120 vac.

Running the same 11 gpm pump at 1750 rpm means 5 gpm out (maybe 1.5 gpm after unloading) but also drops to about 2.5 to 3 hp. I think that is a stretch on 120 vac due to high amps, but if you have a fat, short extension cord it might work. Ask the electrical experts there.

 

[nvrs]

yes, there was a guy, his name is rx7145 and this is his rig...

American Splitter

I am not trying to copy his rig, its way too big for what I am trying to accomplish. I live in a neighborhood of track homes and wish I had the land to put his splitter to good use on, but in California... land is only for the rich.

The 3450 rpm motor shows I looked up only shows a full load amperage of 15.6 amps.

 

[corrupt]

The 3450 rpm motor shows I looked up only shows a full load amperage of 15.6 amps.

Thats what he is trying to say, to run the 11gpm pump at 3450rpm you need 5hp, 3 more hp than that motor will do. but if you go the other motor and run the pump at 1750rpm the 2hp may be ok.

 

[pdhowell]

Hi folks,

I would say that your answer regarding power and electric motor would depend upon the size of the cylinder and your location. A 1750 rpm motor has twice the torque of a 3450 and the pump whine is much less. The smaller pumping volume is partially offset by less friction and cavitation of the hydraulic oil. For a 18 inch cylinder, 3.5 inch wide cylinder, that is OK, at least on my splitter.

With higher pressure components, hoses, ram etc, you can bump the relief pressure to 3000 psi, exceeding the power of a 4 inch ram run at 2250 psi.

My splitter (20 amp, 120 volt or 240 volt, ten amp) would run on 110, but I had problems with breakers tripping with the startup amperage draw.

I switched my motor over to 220 to halve the amperage and allow cold weather starts even below zero with the literal, "flick of a switch". That was one of the reasons I traded out my gas engine.

Electric is nice, cheap to operate, quiet, hassle free if you are in one location.

Maybe this is useful

 

[David (saltas)]

higher voltage gives more torque

torque is proportional to voltage squared.

Start up currents are six to ten times the rated full load current of the motor

Single phase motors are not that efficient 65%ish three phase motors of the same horse power are better than 90% efficient and half the physical size.

the high speed motor is two poles and gets two impulses each revolution the slower motor is four pole and gets four pulsed per revolution

the three phase equivalents will be getting 6 and 12 pulses per revolution

these little snipits don't answer your question but should help you later when you get stuck into sorting it out.

 

[nvrs]

So from what I am gathering, this would be a better motor choice?

 

[nvrs]

Here is the pump and cylinder I am thinking about using with the motor in the post above...

and

Anyone think this will be a bad combo or too slow?

 

[pdhowell]

Similar to mine, and mine works very well. My thought is your present arrangement might be somewhat slow to operate. The problem is the lower volume of oil pumped at 1750 rpm.

Some solutions:

What is the length of your wood? If your wood length is only 18 inches, a 18 inch ram will cycle faster, having less volume of oil to fill taking less time. There is also less stress on the beam with a shorter ram.

Also consider using a 3.5 inch cylinder. The Splitfire and Iron and Oak people have models that seem to work well.

Since you have 3000 psi rated components, use 3000 psi rated hoses. That way you can (safely) bump the relief pressure in the valve to 3000 psi, giving you more splitting force with a 3.5 inch cylinder than a four inch cylinder at 2250, the factory setting for many splitters. Do the math. Hydraulic components like typically have a X4 safety factor. Ie, a 3000 psi hose has a 12,000 psi burst pressure.

The slower electric motor/ pump combination together with a smaller but higher pressure cylinder works better than you you expect. You will have no heating (energy loss) of your oil due to friction and cavitation, and your hydraulic pump whine, your greatest and most irritating noise, is much less. Your splitting power is not diminished.

On the aesthetic side, quiet splitting becomes much more enjoyable, working/ talking together with a helper is so much easier, and you will be surprised how much noise the wood makes as it is torn apart.

Also, wire your motor for 240 and use Automatic Transmission Oil. The pump drag, and motor starting amp draw is much less, allowing you to start your electric splitter splitter at cold temperatures.

Hope this helps,

Dave

 

[nvrs]

So if I ran this cylinder my cycle times would be much less?

and then I could safely bump the pressure up to 2500? or can I go higher?

Thanks for the ATF tip... I will be using it. How big of tank will I need? I was thinking about using 4x4 box tubing for the main beam and using it as part of the tank. As far as the motor goes, 110v is the only way at my dads place unless he will run a 220v line. I would like to figure a way to wire the motor for dual inputs, but that's for later on in the thread.

 

[pdhowell]

OK, let's see...

recalculate using 5.5 gallons per minute for your pump, because your are basically running it at half the rated 3600 rpm that would pump 11 gallons per minute.

That would probably double your out and back times listed. For that it is worth, you have speced almost exactly what I have, and my out and back time is 14 seconds, a close agreement with your information.

However, I rarely run the entire ram out, because most wood splits before then. Some wood, elm, red oak, or other stringy wood requires the entire ram length.

The other factor is that when the valve "downshifts" to the higher pressure but lower volume of oil, when the splitting is tougher, the ram slows down. But that is momentary, a second or so, and then with the initial force breaking the wood apart, the ram goes back to full speed. Upshot, it might be a little longer cycling in the hardest wood.

However, working alone, it is the wood handling that takes time, especially for one person, not the ram travel. While the ram is traveling back, you are stacking or throwing the splits and place the next unsplit round in the splitter.

The other question is yes, with 3000 psi rated components, you can run your splitter at 3000 psi. Most factory splitters come with 2500 psi components and are limited to that pressure. When I put a valve on my splitter, most wood splits at 500-700 psi when the wedge enters the wood. The 3000 psi is reached only when the pump is squealing, as when I try and cut a piece sideways.

For me, a higher pressure, lower volume, shorter throw, quiet splitter is the best there is, if you have the electrical hookup to work with. If not, when I split in the woods, I run the splitter off my generator.

Hopefully helpful, but note I am just a country cobbler with a welder, not an engineer.

Dave

 

[pdhowell]

Oops, sorry about the omission of the tank volume. I don't know for sure, but my splitter uses 4 gallons of atf oil, and at it's lower speed/volume, does not seen to have friction and cavitation issues that heat up the hydraulic oil in some splitters.

I have heard you use the rule of one gallon of oil per gallon per minutes pumped. In that case you would use 5 to 6 gallons of oil.

A larger reservoir is probably better than smaller. Make sure that the return inlets to your tank from the ram is under the nominal oil level to prevent splashing and air entrapment. Some good people have pointed that baffles are useful, or that a linear tank shape with more surface oil is better for cooling hot oil.

Dave

 

[Patrick62]

some thoughts on this subject

Going electric would be really cool.
Electric HP is NOT the same as gasoline HP. The 2hp electric would more than equal a 5hp gas engine in "pulling" a pump. Electric motors are notorious for ability to be overloaded for short periods of time. One such motor would be to locate one rated for air compressor service. Go 220V if at all possible. Losses in wiring are dependant on amperage flowing, and motors don't like voltage drops. I would stay with the 3450 rpm as the pumps are cheaper to get a reasonable flow.

A 3 1/2 cylinder would be a great compromise if really high tonnage isn't required and a faster cycle time is nice. My personal splitter is a 5" and if I had to do it over again I think I would raise the pressure a bit and use a 4 1/2 cylinder.

 

[rx7145]

My splitter uses a 3450rpm motor and a 16gpm two stage pump. The pump will stall the motor at 2400psi. The motor is rated at 4hp. It is a 56C frame motor.

Good luck on your project.

 

[nvrs]

So I was wondering about the engine RPM on a gas motor is usually 3600, and a 5 hp motor usually will drive a 11gpm pump.

Why is it that the 2hp motor running at 3450 would not drive the 11gpm pump? Since it has been said that the 2hp electric is about the equivalent of a 5hp it seems to me that the 3450 rpm motor could be used instead of the 1750(which is what the ramsplitters seem to come with).

I am also still looking to answer the question about the main beam type. My local steel yard has tons of square structural grade tubing in their scrap section. Would this be ok to use as my main beam with a piece of 3/16 plate welded on top? I have seen many splitters bend the H-Beam and I am trying to keep weight down as much as possible without sacrificing the strength.

 

[pdhowell]

I think the answer to your question is found in this link which shows the huge effect of motor speed on torque. Electric motors differ in efficiency , service factor (temporary overload), etc but are similar in that they produce much more power (torque) at lower rpm. Torque drives the hydraulic pump.

Electrical Motors - HP, Torque and RPM

Maybe helpful,

 

[nvrs]

I think the answer to your question is found in this link which shows the huge effect of motor speed on torque. Electric motors differ in efficiency , service factor (temporary overload), etc but are similar in that they produce much more power (torque) at lower rpm. Torque drives the hydraulic pump.

Electrical Motors - HP, Torque and RPM
Maybe helpful,

So the grunt side(torque) is whats more useful in this situation instead of the freewheeling speed. cool, thanks...

Still looking for an answer about the box tubing vs h-beam/rectangular strength issue.

 

[nvrs]

Got the gas side taken care of last night...

Saw that Harbor Freight had discontinued the blue Greyhound engines(cHonda copy) and went to the local store for a tongue box for my new wood trailer and they were $74.97 on "managers special". Used my 20% off coupon and picked it up for $60. Couldn't go wrong with that one. I grabbed 2 just in case one goes bad.