Another hydraulic pump option

[DADSGARAGE]

I have been thinking about using/trying some small pneumatic valves....they're not very costly but they are somewhat big.....and have a low pressure rating...or you just need bigger cylinders...LOL
KP

[RCP57]

Originally Posted by DADSGARAGE

I have been thinking about using/trying some small pneumatic valves....they're not very costly but they are somewhat big.....and have a low pressure rating...or you just need bigger cylinders...LOL
KP

Be careful of the pneumatic rotary valves. My father in-law machined a valve block for my Volvo that was very close to the rotary style that Princess Auto sells. At 30 bar you could barely turn the valves with pliers. Too much surface area for that kind of pressure.

[dsdmax]

Originally Posted by RCP57

Be careful of the pneumatic rotary valves. My father in-law machined a valve block for my Volvo that was very close to the rotary style that Princess Auto sells. At 30 bar you could barely turn the valves with pliers. Too much surface area for that kind of pressure.

I was thinking/planning on making rotary valves. Looks like they would be easier to make versus spool valves (i would be concerned about trying to hold the required tolerance on such a narrow shaft... though maybe if i started with a reamed hole and ordered precision ground shafts to start that might not be too bad... im assuming each spool would need some kind of seal, o-ring? but tolerance between the lands would still hve to be good to keep from leaking between the lands. what is the diameter for one of these mini spools? .125 .1875? something bigger?

If memory serves i think the rotary valves your father inlaw made were smaller than a penny...

sorry - thinking out loud what about pressure release valves? are people making those? buying or ignoring that option? i would assume some adjustability would be nice ... i guess i have to learn something about spring pressure as well... at least making those on a lathe is not difficult...

waiting on my motors from robotmarketplace ... once i get those i can start on mounts and drive train... might need to source some bevel or spiral bevel gears (i dont think the spiral bevels will be necessary or worth the additional cost though).

[RCP57]

Originally Posted by dsdmax

I was thinking/planning on making rotary valves. Looks like they would be easier to make versus spool valves (i would be concerned about trying to hold the required tolerance on such a narrow shaft... though maybe if i started with a reamed hole and ordered precision ground shafts to start that might not be too bad... im assuming each spool would need some kind of seal, o-ring? but tolerance between the lands would still hve to be good to keep from leaking between the lands. what is the diameter for one of these mini spools? .125 .1875? something bigger?

If memory serves i think the rotary valves your father inlaw made were smaller than a penny...

sorry - thinking out loud what about pressure release valves? are people making those? buying or ignoring that option? i would assume some adjustability would be nice ... i guess i have to learn something about spring pressure as well... at least making those on a lathe is not difficult...

waiting on my motors from robotmarketplace ... once i get those i can start on mounts and drive train... might need to source some bevel or spiral bevel gears (i dont think the spiral bevels will be necessary or worth the additional cost though).

You are right about the valves my father in-law made... He made two sizes. The first one he made had 1.5" plugs and didn't work(couldn't turn it with pliers). The second valve was made small like you said (5/8" plugs)and is what operates the hydraulics in my Volvo excavator. It has worked very well with no issues other than it leaks down a little. In an attempt to fix things he also increased the tolerances in the valves when he made the smaller setup and this lead to the leak down issues. I made my own valves for my Tigercat but have yet to run fluid through them...