So I built a hydraulic pump today

[RCP57]

I spent about 8 hours in the shop today and managed to make a hydraulic pump. It doesn't make a lot of pressure but I am just happy that it worked:D:D! Maybe the next one will perform better.:cool: http://youtu.be/ZWwlhNsWjiw
http://i1293.photobucket.com/albums/b588/RCP57/IMG_1658.jpg
http://i1293.photobucket.com/albums/b588/RCP57/IMG_1659.jpg
http://i1293.photobucket.com/albums/b588/RCP57/IMG_1660.jpg
http://i1293.photobucket.com/albums/b588/RCP57/IMG_1661.jpg
http://i1293.photobucket.com/albums/b588/RCP57/IMG_1662.jpg
http://i1293.photobucket.com/albums/b588/RCP57/IMG_1663.jpg
http://i1293.photobucket.com/albums/b588/RCP57/IMG_1664.jpg

Thanks for looking!

[fhhhstix]

Good job with the pump. It may work just fine for a conversion. Hopefully your next attempt will produce more PSI but if not at least you can say you did it.


Travis

[RCP57]

Thanks, I got the motor and pump quite hot while trying to prime it before I decided to quickly make a tank that would gravity feed the pump. It only made 100 psi that way but when I took the misses out to the shop for a demo it had cooled down and went right up to 125 psi. I think I might be able to lap the two halfs of the body and reduce the end play in the gears but I'm not sure if it will gain much. I have one more pair of gears so now that I know that I can do it I may build on out of brass or steel. At least it wouldn't be as effected by heat soak then. At any rate it was a fun experiment(only because it kinda works) that cost less than $10 to build.

Reg

[Espeefan]

100 PSI is nothing to shake a stick at! For a first attempt, that's awesome.

[doodlebug]

Hey Reg, Way to go! Have you considered building a heat sink for the motor? http://www.amainhobbies.com/product_info.php/cPath/1_221_580/products_id/25146/n/Novak-HV-Brushless-Motor-Heat-Sink?utm_source=Google-Base&utm_medium=cpc&utm_campaign=Product-Feeds&source=google_ext&gclid=CPG0q7-ZsrQCFexAMgodlxYA4w Keep it up!
Cheer's, Neil.

[mazdaparts]

Would helical cut gears make any difference? Or would overdriving the gears change anything instead of direct drive.

[steamer]

Looking good Reg. Thanks for the BS session. Looking forward to the updates.
Rob

[Iron Art]

Reg, Don't you think that without flow that pump would be expected to generate a lot of heat and might not last long . Some type of open center solonoid valve or a relief valve would be the cure and I think the pump performance would be even greater than what you observed due to the cooler oil temp. You are on the right track with your design, Good JOB! Fred

[RCP57]

Reg, Don't you think that without flow that pump would be expected to generate a lot of heat and might not last long . Some type of open center solonoid valve or a relief valve would be the cure and I think the pump performance would be even greater than what you observed due to the cooler oil temp. You are on the right track with your design, Good JOB! Fred

Yeah you are right Fred. I just wanted to quickly see if it worked last night so that was how I hooked it up. I dug through my fittings this morning and hooked it up with a relief valve. It doesn't pump any more pressure but at least the oil has somewhere to go. I also drilled out the inlet and outlet to a larger size and although it helped with volume it is still starving a little so I may open up the inlet side more if I can. I'll keep poking at it until I destroy it or get it to work right! At least it was a little bit successful so now I'm inspired to keep trying.

Well gotta get back to wrapping gifts...

Merry Christmas!

[RCP57]

http://youtu.be/2bQNXtrWiIA
I did a little tweeking to this today. I managed to get it to pump a little more pressure and quite a bit more volume. After opening up the ports I put it back on the mill and took a skim off the gear case. It seems to have helped as it makes 150+ psi for a short time and pumps 125psi steady without fading. I guess I won't be in the shop tomorrow but maybe if I was really good this year I will get something new to play with from Santa. If I get what I asked for then this pump will be just right....;)

Reg

[Lil Giants]

Using that machinist's playdo for a tolerance checker, not sure what it's called, but I've used it in the past when re bearing rod & crank journals.. it'd make it easy to measure your cover atop your gears.. the closer you get to zero, the better & more reliable your pressure will be. ;)

The inlet port on my Jung is like 8mm (?) vs 4mm on the pressure side.

Good work on the pump.. you'll be our cdn manufacture of scale hyds in no time! :cool:

[Madda]

From where did you get the gears?

This looks very promising, I hope you get it running!

[RCP57]

Yeah Joe, I need to pick up some plasti gauge or something like that to see exactly how much clearence is still in there. I would like to make the inlet larger but the way I built this one it is hard to do. I guess I will have to try again with the knowledge I've learned from this one. I would love to build these for people like yourself but I think I have a lot to learn yet. You would be the perfect R&D person though...

Madda, The gears are cast iron and came from the private stash of an employee at a local hobby shop. I have two sets so I can built another pump and keep this one together.

Reg

[steamer]

Reg, Great progress. Got lots of volume now and it's starting to perform better. When you get the end clearance just right, it will be a winner for sure!
Rob

[RCP57]

Yeah thanks for the input Rob! A little more attention and it will work great or be ruined! Haha

Reg

[RCP57]

My in-laws bought me a really nice dial indicator for Xmas so that should help with accuracy.

[D8R]

My small experience from hydraulic pumps that has been dismantled is that there´s a realy tight fit inside where the gears are. Oil will find its way around if possible. Guess that the indicator can help you.
/Dan

[RCP57]

It should help with setting up the piece on the machine anyway. Unfortunately the rest is up to my ability to turn the handles:eek::confused::confused::confused::confuse d::o I will try it again with a piece of steel soon. I have managed to get it to pump over 225 psi for a very brief period and 175 consistantly but the standard buna o ring can't take the strain. When I get a day off from work I will go to the local hydraulic shop in town and get some better o rings. If I could get this one to seal properly I think it would work well enough for a small model though.

Reg

[gauthib12]

great job on the pump, that is very good for a first go!! curious how did you seal the back where the motor goes?

Thanks,

[chaseracer]

impressive great job Reg!!!!!

[Goose19]

I have managed to get it to pump over 225 psi for a very brief period and 175 consistantly

i have precisely 0 experience with small hydraulics for our hobby......how much pressure do you need? i mean 100psi in pneumatic form holds my 1:1 big truck off the ground (tire pressure) surely the same in hydro would dump a dump box or run a loader?

Very impressive work!!!!!

-Allen

[RCP57]

i have precisely 0 experience with small hydraulics for our hobby......how much pressure do you need? i mean 100psi in pneumatic form holds my 1:1 big truck off the ground (tire pressure) surely the same in hydro would dump a dump box or run a loader?

Very impressive work!!!!!

-Allen

My models are all 1/10 scale so they need a little more juice than most but I would be happy with this if it would make 200psi. My Volvo excavator runs over 425psi but it all depends on cylinder size and what you expect it to be able to do.

Thanks
Reg

[RCP57]

I've been messing with this(big mess, oil everywhere) a bit lately and I need some advice on the shaft seal. I've got the pump to produce around 12bar or 175psi without any trouble but the o ring(now 2) on the shaft can't take the pressure. I have tried standard rubber, Viton and harder rubber with no success. Does anyone know what the manufacturers use on this style pump? I'm trying to seal the 1/8 motor shaft. Pictures of any working set ups would be nice to see too!

Thanks, Reg

[Jw.]

What kind of o-rings are you using?

Have you looked in to square type o-rings? I believe this is the type they would be using on these pumps. Have anyone taken apart a Jung pump on here? I would be interested to know as well.

Similar to these...
http://www.theoringstore.com/index.php?main_page=index&cPath=700

[Jw.]

This might be of some help.

http://www.rlhudson.com/O-Ring%20Book/designing-dynamic.html

Look at rotary seals and table 53. It lists dimensions for a 1/8 shaft using a round style o-ring.

[Supermario]

My models are all 1/10 scale so they need a little more juice than most but I would be happy with this if it would make 200psi. My Volvo excavator runs over 425psi but it all depends on cylinder size and what you expect it to be able to do.

Thanks
Reg

Wow! 425psi! I never realized that some RCs run at that high of a pressure! That's close to pilot pressure on a 1:1 excavator:eek:

I don't deal with microscopic pumps like this at work but I know that to prevent pump cavitation a safe rule is 3:1 inlet size vs outlet. The fact that this is a gear pump a 2:1 ratio is fine just like Joe said 8mm inlet / 4mm outlet.

Any chance of using a lip seal for the shaft instead of. O rings? Do you have enough material to mill a bore for a lip seal? I can think of a few items that use a 1/8th shaft lip seal at work.
I'll see if they have one in the parts dept tomorrow, take a picture and send to ya.

Mario

[Supermario]

Reg, thought about it some more, with a shaft that small, it's not a lip seal but a oring for sure. Like I said, I'll check and see what I can find for you.

Mario

[pugs]

Should be able to get quad rings that small.

[cdm]

it actually is rather scale......

http://www.cat.com/cda/layout?m=383895&x=7

Main System – Maximum Flow (Total) 232 gal/min
880 L/minSwing System – Maximum Flow 95 gal/min

Maximum Pressure – Equipment – Normal 5076 psi
35000 kPaMaximum Pressure – Travel 5076 psi
35000 kPaMaximum Pressure – Swing 4264 psi

we use 1 pump for everything (or in the usual case, electric motors)

if we scale that psi down to scale, say 1/14.5 that would mean

350psi main which is kinda in the league of vario. a cat 320 has the same pressure as a 374.. the flow varies.

however the flow should be 16 gallons a minute.. and it flows at what rate? around a litre! that's the part that isn't scale. because flow = big gears = resistance = power = big motors and big power drain.

now the other big thing is weight:

back to the 374 - Operating Weight 156819

in scale weight = 10815lbs


although my weight calculations could be wrong. not sure if scale weight is calculated any different than linear size

now keep in mind that models are made out of aluminum. if dense carbon steel is used, weight could easily be doubled or tripled. but that is a whole other mess on its own using steel

[pugs]

Volume doesn't scale same as distance

1/14th scale, 14 feet would be 1 foot, but 14 cubic feet would be .0051 cubic feet

So your scale weight example would be 57.14 lbs in 14th scale

[RCP57]

Thanks for the ideas guys. I did find a U cup seal on line in 1/8 so they are available. My local hydro shop didn't have any in stock that were 1/8 but said they could get them. They gave me the different O rings to try but didn't think they would work. I guess they were right. I guess I should make a new housing that has more meat on the back side. that would give me more room to install a proper seal. My Jung pump has a proper U cup seal but the shaft is larger too giving a lot more sealing surface. I'm wondering if the bushing in the motor is allowing the shaft to load one side of the O rings heavy when the pressure comes up:confused:. There always seems to be a little slack in these brushed motors but the original shaft length is long enough to use a support bearing on the other side. Maybe I should try that too? I put it back in the box and stuck it on the shelf because I was frustrated but I will get it on the bench again soon!

Reg

[WhiteWolf McBride]

Reg,

If you're going to try for a second edition/incarnation, and might want to dispose of the first, I might be interested, if it can handle water decently, as in a water-cannon pump.

I'd even be willing to send you my small Thunder-Tiger one that runs off what I think is a 180 (have to check it) as its unobtanium, and if you can replicate it at a decent price, I know guys that would ~kill~ for it.

Also, have you thought of running ssome of the oil thru the casing to cool it, and possibly thru a coil wrapped around the motor to cool ~that~... and if not oil, use a loop of water with some sort of a radiator.

WhiteWolf