So I built a hydraulic pump today

[RCP57]

Originally Posted by Goose19

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.p...ndex&cPath=700

[Jw.]

This might be of some help.

http://www.rlhudson.com/O-Ring%20Boo...g-dynamic.html

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

[Supermario]

Originally Posted by RCP57

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

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