Anyone know about hydraulics? (ID - Picture)

[stihl036]

Hey,

I have a hydraulic pump and want to make sure it is big enough to run a log splitter.

On the tag it reads:

Webster Electric Company
3HCS14 1L
263552 A74


Anyone know where I can get info/specs on this pump?

Thanks,

WW
http://img.photobucket.com/albums/v512/ivysmommy/WebsterPump.jpg

[muddhunter]

Well if you put a big enough piston on it, any pump will do! Just might not be as fast as you want it to be. I would try searching google, if nothing turns up there, make a few calls to a local hydraulic supplier and see if they have any info. The guys at Hyseco are very knowledgeable. Got any more pics of the whole pump?

[crazyguy]

anything hydraulic should power a log splitter. just depends how fast you want it to go.

[stihl036]

From WEBTECH email
Ref. your enquiry for above pump,details as follows
1.91 cu.in/rev.
2400 rpm max.
1500 p.s.i. max.
helical gears.
L.H. rotation.
tang shaft.
end ports 3/4"-14 NPTF.
mounting bolt centers 4.19"
spigot 1.780" dia.


I am new to all this so can anyone tell me if this is going to be ok for a logsplitter before I start building? I was surprised to see that there was no rating of gallons/minute.

This is my calculation:

1.91 cu.in/rev. X 2400 rpm max. = 4,584 cu.in/minute max.

4,584 cubic inch = 19.84 gallon [US, liquid] (according to http://www.onlineconversion.com/volume.htm)

So, I figure I have almost 20 gallons per minute of flow at max rpms. Seems like plenty for the log splitter but what about the max psi of 1500? Most other pumps max out at 3,000 psi. Is the psi of the pump too low?

Here is the pump I am comparing it to: http://www.northerntool.com/webapp/w...Product%20Page

How do I convert gpm to ram pressure. I plan on using the typical log splitter ram (4" X24" stroke).


Can anyone check my calculations? Is the pump going to be fast/strong enough?

Thanks,

WW:D

[jasonmt]

Long reply below:


Rule of thumb:
Horsepower=(GPMxPSI)/(1714xEfficency)

So if you want 3 GPM@1500psi(g):

HP=(3GPMx1500psi(g))/(1714x0.90Efficency)
HP=4500/1371.2
HP=2.92 with 3HP being the closest motor.
You would want to spin the pump at ~403RPM to ensure that you had no problems with overworking your motor.

5 GPM @ 1500 psi would require ~4.86HP and the pump spinning at 671RPM which is still pretty slow for a gear pump.

Volumetric efficiencies of gear pumps run as high as 95% under optimum conditions. Running clearances between gear faces, gear tooth crests and the housing create an almost constant loss in any pumped volume at a fixed pressure. This means that volumetric efficiency at low speeds and flows is poor, so that gear pumps should be run close to their maximum rated speeds.

As the energy input from the power source is going to be a static number you can play with the variables of flow and pressure (energy output less losses due to friction, seal leakage etc.) to attain a combination that will suit your intended use and power source.

Basically that pump is WAY too big for what you want it to do and due partially to its size it has a lower maximum pressure which limits the force that the ram transfers to the splitter. Another problem would be that I doubt that it is designed for side loads on the input shaft which makes adjusting the input speed from the motor a more complicated affair that simply throwing on a set a sheaves/sprockets and a belt/chain. A typical Haldex-Barnes 2 stage pump used on splitter has a displacement of 0.517 cu in on the low side and 0.194 cu in on the high and requires a 5HP motor.

I would be more inclined to design a splitter hydro system around a smaller displacement gear style pump that can have high overall efficiencies (95% for some gear pumps versus 80% for the piston) as well as higher RPM ranges and higher maximum pressures.

A gear pump that is 95% efficient with a displacement of .231 cu. in. and a maximum speed of 4500RPM will match up great with a 5HP 3400RPM motor and allow it to be direct driven. With this setup you are looking at 3.23GPM @ 2500 psi and the smaller gear pumps usually have fairly high maximum pressure with a Haldex-Barnes .231 cu in model having a maximum pressure of 3150psi.

Similarly a .129 cu in displacement pump is a good match for a 3HP/3400 RPM motor and will provide 1.9GPM @ 2500 psi and require 2.9HP to run.

[stihl036]

Originally posted by jasonmt
Long reply below:


Rule of thumb:
Horsepower=(GPMxPSI)/(1714xEfficency)

So if you want 3 GPM@1500psi(g):

HP=(3GPMx1500psi(g))/(1714x0.90Efficency)
HP=4500/1371.2
HP=2.92 with 3HP being the closest motor.
You would want to spin the pump at ~403RPM to ensure that you had no problems with overworking your motor.

5 GPM @ 1500 psi would require ~4.86HP and the pump spinning at 671RPM which is still pretty slow for a gear pump.

Volumetric efficiencies of gear pumps run as high as 95% under optimum conditions. Running clearances between gear faces, gear tooth crests and the housing create an almost constant loss in any pumped volume at a fixed pressure. This means that volumetric efficiency at low speeds and flows is poor, so that gear pumps should be run close to their maximum rated speeds.

As the energy input from the power source is going to be a static number you can play with the variables of flow and pressure (energy output less losses due to friction, seal leakage etc.) to attain a combination that will suit your intended use and power source.

Basically that pump is WAY too big for what you want it to do and due partially to its size it has a lower maximum pressure which limits the force that the ram transfers to the splitter. Another problem would be that I doubt that it is designed for side loads on the input shaft which makes adjusting the input speed from the motor a more complicated affair that simply throwing on a set a sheaves/sprockets and a belt/chain. A typical Haldex-Barnes 2 stage pump used on splitter has a displacement of 0.517 cu in on the low side and 0.194 cu in on the high and requires a 5HP motor.

I would be more inclined to design a splitter hydro system around a smaller displacement gear style pump that can have high overall efficiencies (95% for some gear pumps versus 80% for the piston) as well as higher RPM ranges and higher maximum pressures.

A gear pump that is 95% efficient with a displacement of .231 cu. in. and a maximum speed of 4500RPM will match up great with a 5HP 3400RPM motor and allow it to be direct driven. With this setup you are looking at 3.23GPM @ 2500 psi and the smaller gear pumps usually have fairly high maximum pressure with a Haldex-Barnes .231 cu in model having a maximum pressure of 3150psi.

Similarly a .129 cu in displacement pump is a good match for a 3HP/3400 RPM motor and will provide 1.9GPM @ 2500 psi and require 2.9HP to run.

Jasonmt,

Thank you for the response. I have always been impressed with your detailed responses! I am new to this stuff so please bear with me.....alot of this is over my head. (I do have a degree so hopefully some of the math/physics comes back!)

I have access to this pump and a Robin 8 HP motor (both are free!) I want to make these things work together, if possible. Here is sorta what I was thinking.

The 8hp max probably comes at about 4000rpm so at about 2400 rpm I am thinking it will be about 4hp continuous. This seems like enough power to me but I don't know. Will it bog the Robin motor down too much?

I used the specs on this motor (not exact) but should put me in the ball park. http://www.robinsubaru.com/engines/detail.lasso?mdl=EX21&cls=Overhead%20Cam

Then...from this site I did the following calculations for a 4" ram.

http://science.howstuffworks.com/hydraulic2.htm

4-inch piston has an area of 12.56 square inches. Pump generates a maximum pressure of 1,500 pounds per square inch (psi) so , the total pressure available is 18,840 pounds of pressure. So I get 18,840 psi/2000 = 9.42 tons. Seems like the pressure is too low compared to commercially available splitters.

From the same site I roughly calculate the cycle time.......4-inch-diameter piston 24 inches, you need 3.14 * 4 * 24 = 301 cubic inches of oil. A gallon of oil is about 231 cubic inches, so you have to pump almost 1.303 gallons of oil to move the piston 24 inches in one direction.

So with a max flow rate of 19.84 GPM it would take 1.303gallons/19.84 GPM = 0.0657 minutes (or 3.94 seconds) to travel in one direction so about 8 second for a complete cycle. Seems like the speed is too fast, I may cut one of my fingers off!!!

So what I am thinking is.....get a larger diameter ram. This should increase the pressure and decrease the speed. Make any sense?

A) 7" X 24"stroke? (For a 7" ram I get 28.58 tons and 24.2 second complete cycle)

B) 6" X 24"stroke? (For a 6" ram I get 21.2 tons and 17.76 second complete cycle)

C) 5" X 24"stroke? (For a 5" ram I get 14.7 tons and 12.3 second complete cycle)

This is the best I could come up with (I like option B) but I still don't really know if my motor/pump will work together.

If I have to buy a new pump I may as well buy the Princess Auto splitter and save myself a whole pile of time but I am doing this as a learning experiece (thinking hydro tube bender in the future) so I really hope I can make this work.

Any insight?

Thanks again!

WW


:beer :beer

[muddhunter]

If your worried about losing fingers, you can always slow down the flow with a variable flow control.

[jasonmt]

Originally posted by stihl036



A) 7" X 24"stroke? (For a 7" ram I get 28.58 tons and 24.2 second complete cycle)

B) 6" X 24"stroke? (For a 6" ram I get 21.2 tons and 17.76 second complete cycle)

C) 5" X 24"stroke? (For a 5" ram I get 14.7 tons and 12.3 second complete cycle)

This is the best I could come up with (I like option B) but I still don't really know if my motor/pump will work together.



My biggest problem with this subject is remembering that there are both mechanical and volumetric efficiencies to account for and when to apply them. I am not even claiming that I have not made any mistakes in this area below but with the size of the system it is not going to be critical and I am a little bit rusty on this subject matter.

The first problem I see with both your planned set-up and calculations is that there is NO WAY that a 5HP gas motor is going to be able to produce the flow you envision at 1500psi. Using the formula from my first post you would require a 20HP motor spinning at 2400RPM to produce 17.85 GPM@1500psi(19.84GPMx90% Volumetric Eff.). This is a conservation of energy as the input power from the motor cannot be exceeded by the output power of the pump which is going to be a factor of flow, mechanical efficiency and pressure.

The second problem is that by attempting to solve your 1500psi pressure limitation by using a bigger bore cylinder you are going to be spending way more additional money on both a 6x24” cylinder and attempting to mount your existing pump to your existing engine with a 6.5:1 drive ratio (3600RPM motor output to 550RPM pump input) in order to ensure that you do not overload the motor. If it is direct coupled to the motor at a 2400RPM drive speed and a 4HP power output as soon as you start to go above ~300psi the input power requirements of the pump are going to exceed to power output of the gas motor and while I cannot predict exactly what would happen it would not be a good result.

Limiting the input speed of your existing pump to ~550RPM is what ensures that the power in/power out (conservation of energy) matches and does not overload you motor.

If you want to end up with ~20 Tons of force from the ram you could use a 6x24” @ 1500psi for 21.2T OR a 4x24” @ 3000psi for 18.8T. I bet you would find it would be cheaper to buy a 4x24” cylinder and the smallest 2 stage Haldex-Barnes pump ($200, 0.517 cu in on the low side and 0.194 cu in on the high, 3000psi max, 500-4000RPM input range) from Princess Auto than it would be to just buy a 6”x24” cylinder.

The advantages of going with the two stage pump are numerous such as:

Direct mount and couple to your engine with a $50 mount and $20 spider kit from PA, at 3600RPM and 5HP it is just about a perfect match with a fluid flow of ~2.7GPM @ 3000psi.

4000RPM max speed on the pump and motor makes it almost impossible to over-speed the pump with the motor.

Two stage design gives you fast extend and retract speeds with low pressure (under ~ 700psi) and switches over to the smaller displacement to hit 3000psi.

3000psi output means you can use the cheaper 4” bore cylinder and still get 18.8T of force.

No need to worry about the complexity and expense of attempting to reduce the output speed of the motor to the input speed of the pump and not side load the shaft.

[stihl036]

My biggest problem with this subject is remembering that there are both mechanical and volumetric efficiencies to account for and when to apply them. I am not even claiming that I have not made any mistakes in this area below but with the size of the system it is not going to be critical and I am a little bit rusty on this subject matter.

The first problem I see with both your planned set-up and calculations is that there is NO WAY that a 5HP gas motor is going to be able to produce the flow you envision at 1500psi. Using the formula from my first post you would require a 20HP motor spinning at 2400RPM to produce 17.85 GPM@1500psi(19.84GPMx90% Volumetric Eff.). This is a conservation of energy as the input power from the motor cannot be exceeded by the output power of the pump which is going to be a factor of flow, mechanical efficiency and pressure.

The second problem is that by attempting to solve your 1500psi pressure limitation by using a bigger bore cylinder you are going to be spending way more additional money on both a 6x24” cylinder and attempting to mount your existing pump to your existing engine with a 6.5:1 drive ratio (3600RPM motor output to 550RPM pump input) in order to ensure that you do not overload the motor. If it is direct coupled to the motor at a 2400RPM drive speed and a 4HP power output as soon as you start to go above ~300psi the input power requirements of the pump are going to exceed to power output of the gas motor and while I cannot predict exactly what would happen it would not be a good result.

Limiting the input speed of your existing pump to ~550RPM is what ensures that the power in/power out (conservation of energy) matches and does not overload you motor.

If you want to end up with ~20 Tons of force from the ram you could use a 6x24” @ 1500psi for 21.2T OR a 4x24” @ 3000psi for 18.8T. I bet you would find it would be cheaper to buy a 4x24” cylinder and the smallest 2 stage Haldex-Barnes pump ($200, 0.517 cu in on the low side and 0.194 cu in on the high, 3000psi max, 500-4000RPM input range) from Princess Auto than it would be to just buy a 6”x24” cylinder.

The advantages of going with the two stage pump are numerous such as:

Direct mount and couple to your engine with a $50 mount and $20 spider kit from PA, at 3600RPM and 5HP it is just about a perfect match with a fluid flow of ~2.7GPM @ 3000psi.

4000RPM max speed on the pump and motor makes it almost impossible to over-speed the pump with the motor.

Two stage design gives you fast extend and retract speeds with low pressure (under ~ 700psi) and switches over to the smaller displacement to hit 3000psi.

3000psi output means you can use the cheaper 4” bore cylinder and still get 18.8T of force.

No need to worry about the complexity and expense of attempting to reduce the output speed of the motor to the input speed of the pump and not side load the shaft.

Looks like it is back to the drawing board for me. Thanks for the response, it really helps, I am learning alot.

WW

[westcoaster]

After reading all of this, it would appear to be a lot simpler and more rewarding to take all of your frustrations out by swinging an axe at a log....