hydraulic pumps

hackberry jake · May 20, 2012, 10:13:43 PM

Ive been doing my research on a hydraulic power source. All the options are mind boggling. I have a hydraulic log splitter. Is there any reason I couldnt just put some quick connect fittings in line on the splitter and use it as a power source?

Josef · May 20, 2012, 10:49:08 PM

Hi Jake,

depends on your application, most log splitters use a two stage pump, which senses load and shifts to a lower gpm/higher press output condition which while very desirable on gnarly firewood would present control issues in other applications, just when you were applying a significant load the pump would decrease flow to accommodate the load.

What are you trying to supply hydraulic power to? Any idea the system pressure and flow requirements to size a power supply?

Joe

hackberry jake · May 20, 2012, 11:23:40 PM

I was thinking a 3hp electric motor with a 3 or 4 gpm pump.

hackberry jake · May 20, 2012, 11:25:33 PM

It's for a hydraulic turner/clamp

Josef · May 20, 2012, 11:33:57 PM

Easy enough, are you trying to assemble a power pack from parts or trying to fab one up from scratch? Surplus center has lots of components that would make assembling one easy enough. Without getting into design parameters your hp to gpm is within reason and small enough to be economical.

Joe

Josef · May 21, 2012, 01:41:22 PM

Do you already have the 3hp motor, electric or gas?

hackberry jake · May 21, 2012, 03:21:42 PM

I have two planers at the moment, a 5hp woodmaster and a 3hp RBI. I am planning on borrowing the motor from the RBI for the pump.

Josef · May 21, 2012, 03:42:12 PM

from the nameplate data can you check the rpm's of the motor (1725 or 3450) and the frame designation, is it a 115/230 volt motor or single voltage, amps at full load, what is the rotation, and what is the shaft size.

In general most smaller hyd pumps, less than .6cu in, are rated at about 2000 rpm and maxed at 3000 rpm and it's easy enough to calculate the kw necessary to achieve the pumps rated capacity.

Most small pump models are available in either cw or ccw rotation. The motor frame type will determine if the pump can be directly mounted of separated on a foot mount. Knowing what you have to mate the pump to will make it simple to assemble the components to build a complete power pack from SC parts.

As far as individual components the electric motor is the single most expensive piece (not to imply that the rest of it will be inexpensive) but having the motor helps keep the bottom line more palatable.

Joe

hackberry jake · May 21, 2012, 05:52:33 PM

I'll have to check on my motor information when I get home. If I have a cw motor, would I want a ccw pump? And I don't think my motor has a way to mount a plate on it so I think I'm going to have to get a faceplate for the pump and build a mount for the motor. Then I'll need a three piece coupler. There sure is a lot to hydraulic systems. Do most log handling systems run in the higher pressure ranges (2500 to 3000)? And should I run a pressure relief valve?

Josef · May 21, 2012, 08:03:11 PM

Rotation is usually viewed from the shaft end, so you are correct, if your motor is cw then the pump needs to be ccw. The foot mount will allow the independent planes of the motor base and pump foot base to be accommodated. A three piece flexible coupling will join the two. Many hyd systems (read pumps) are based on a 2500 to 3500 psi max range if you need to get every ounce of energy from the system. Keep in mind, the higher the set pressure the more work the motor has to do, so a system set for 1500 psi will last longer than one set for 3500 psi. Check the pump ratings, for example the DYNAMIC GPF2008S9C HYD PUMP on SC is rated at 2000 rpm and a max press of 3600, but if the system will operate sufficiently at 1500 psi it will operate at a motor load well below the the thermal overload of the 3 hp motor. This pump is rated at 3.87 gpm at 2000 rpm, so doing the math would give you 3.37 gpm at 1725 rpm, within the 3 to 4 gpm you're looking for.

To give you an idea of the forces generated by a system set for 1500 psi, a 2" cylinder will generate over 2 1/2 tons of force on the extend stroke of that cylinder and at 3.37 gpm it will fully extend a 15" long cylinder in under 4 seconds, conversely, a 2 1/2" cylinder will generate over 3 1/2 tons of force on the extend stroke of that cylinder and at 3.37 gpm it will fully extend a 15" long cylinder in 6 seconds. Almost all my hyd packs are set for under 1800 psi, and some have been in service since '87 without failure. Most important item to consider is filtration, keep it clean, replace filters regularly (annually unless you decide to install a hobbs and change by hours or install a differential pressure indicator for monitoring)

The pressure relief on the system can be addressed in a low flow system like this thru the integral relief valve on your open center valve body (make sure you buy one with an adjustable relief valve).

In most instances we start out at 1500 psi and see if the internal losses (friction and turbulent flow losses thru the piping and fittings) restrict performance to the point of being problematic, if the system performance needs to be increased we increase the system pressure about 100 psi at a time and see if we can tweak the system to get the reaction times we're shooting for. At the same time we watch the motor load with a clamp on ammeter at max flow conditions to make sure we don't push the motor too much. There are many other design parameters that you can evaluate, laminar vs turbulent flow, heat losses, etc when designing a system, but the more you can keep it simple the better, don't push the envelope by designing to the max ratings of any component and it's hard to go wrong.

hackberry jake · May 21, 2012, 08:20:29 PM

Roughly half the cost of parts is going to be the control valves. Is there a cheaper alternative? I need 5 for everything, might skip the toe boards which would put me at only 3. Maybe I can find a couple used ones off a tractor or something. I'll keep my eyes peeled.

Josef · May 21, 2012, 08:54:54 PM

you might look at SC # 9-9813, 2 spool valve, gang three of them them together with 9-1556 to get the relief valve, three of the 9813 valves and one 1556 would be just over 200 dollars and would give you 6 individual circuits.

Josef · May 21, 2012, 09:06:07 PM

just checked my last material list for a 5 gpm power pack for a friend in NY (no fittings beyond the power pack) and since he already had a 5 hp farm duty motor from TSC the rest came in just under $500 last year. That was pump, sae/jic/npt adapters, hoses, filter assy, tank, isolation valves, coupling halves and insert, pump foot, sight level/thermometer, bolts and angle iron for base.

mikeb1079 · May 21, 2012, 09:17:07 PM

josef thank you for the informative posts i too am interested in adding hydraulics to my mill and would like to learn more about basic hydraulics. you seem to know your stuff. can you recommend any books or videos for the beginner?

pineywoods · May 21, 2012, 10:04:54 PM

The most new pump for your money is usually a log splitter pump. You actually get two pumps for the price of one. The two are plumbed in parallel internally. Pressure relief for one is usually set to 300-400 psi, the other usually around 2000-2500. LT40 with home-made hydraulics right down the road from me. Uses log splitter pump and 3 hp electric motor. Check with member Jermy2300. think he went the same way.

Josef · May 22, 2012, 01:31:05 PM

mikeb1079,

don't have any recommendations on videos, but for sketching out a system the catalog put out by Hydraulic Supply Company (www.hydraulic-supply.com) has a tech info section that has a lot of design criteria explained. And their catalog listings are pretty comprehensive as far as the tech specs of the individual parts. Catalog is free but is about 2 inches thick. I have lots of old course texts that look good on the shelf but in all honesty are 98% theoretical and 2% real life applicable.

And don't be bashful about calling the product manufacturers themselves for advice, they all have engineering and service depts that I've always found to be friendly and forthcoming with do's and don'ts about their own products. Since I am a bit of a packrat and buy old inventories when I can I am always calling them to get spec info on old hydraulic parts, you know that $10 hyd motor that looks like it will work but if I just had the specs I would know for sure its design displacement, press rating and rotation. (easiest way to confirm your prime mover and pump are adequately matched is to call the pump manufacturer, only takes a few minutes and you don't have to deduce anything)

But I guess the cornerstone of any design is if you don't overload it it probably won't fail.

sgschwend · May 22, 2012, 10:23:07 PM

When I was building my mill I tried a log splitter to check things out.

It worked well for both the feed and the log clamps. I think you will be happy using the splitter, if anything it will be a bit fast but you can idle the engine down, or add a flow control valve.

mikeb1079 · May 22, 2012, 10:36:23 PM

Quotedon't have any recommendations on videos, but for sketching out a system the catalog put out by Hydraulic Supply Company (www.hydraulic-supply.com) has a tech info section that has a lot of design criteria explained. And their catalog listings are pretty comprehensive as far as the tech specs of the individual parts. Catalog is free but is about 2 inches thick. I have lots of old course texts that look good on the shelf but in all honesty are 98% theoretical and 2% real life applicable.

thanks very much josef. the 98% theoretical and 2% applicable was the impression i got when looking for books to buy on the subject. :D i'll have to look into the catalog, as i'm the same boat as jake: manual mill and wanting to add hydraulics.

hackberry jake · May 22, 2012, 11:23:21 PM

What does "power beyond" mean?

Banjo picker · May 23, 2012, 06:21:22 AM

Jake you would like those toe boards...just saying.... ;) ....Josef thanks for posting..interesting read...Banjo

pineywoods · May 23, 2012, 09:43:55 AM

Quote from: hackberry jake on May 22, 2012, 11:23:21 PM
What does "power beyond" mean?

It means you have the option of hooking the outlet of a bank of valves to the inlet of a second bank. Normally, the outlet goes back to the oil tank. There's a little more to it than that, but thats the general idea. I tend to shy away from doing that, I like the stackable valves from prince. Gives you the option of custom sizing the valve bank and adding to it later without worrying about more hoses and fittings. Hoses are expensive...

Josef · May 23, 2012, 10:24:31 AM

I'd add to pineywoods answer that if you decide to use a power beyond valve, be sure to add a separate return to tank circuit to prevent back pressure on the return piping when utilizing the power beyond port.

You might find this link helpful http://www.baumhydraulics.com/files/infobuild/terms_hydraulic_control_valve.pdf
another one of those good internet resources, lots of good basic info.

And pineywoods is absolutely correct, it's hard to beat the prince stackable valves for their versatility and ease of use when putting together a system.

Josef · May 23, 2012, 10:29:51 AM

Here's a link to a schematic of a basic power beyond circuit from the same website, easy to understand and follow

http://www.baumhydraulics.com/files/infobuild/basic_hydraulic.pdf

Joe

hackberry jake · May 23, 2012, 10:37:41 AM

I think I have most of the basic info I need to start fabricating. I would be lost without the forestry forum. Special thanks to pineywoods and Josef for putting up with all my rookie questions.