Pneumatic Hydraulics Are So Fricken Fun!!!!



How did I not know about Pneumatics before now?!? They are just like the hydraulics on your backhoe, except they are super cheap and easy and fun- and they don’t smell, won’t ruin your shirts, and won’t turn your arm into a meat pie (warning! gross!!!).

Today I share with you the full breadth of pnuematics wisdom that I’ve painstakingly acquired over the course the last 20 minutes so you can start playing with them too.

Full video after the break….

The video

The actuator

The ports are the threaded holes that you put the air into. Then the air pressure moves the piston. 100PSI seems like enough to really make these move.

The bore is the inside diameter of the tube. The bigger this is, the more force you get since you have a bigger surface for the air to push against. Bigger bore also uses more ait per move.

The stroke is the distance that the rod moves in and out. Longer is usually more expensive, and longer also uses more air.

Dual acting cylinders have two ports. These push when you send air into one port, and pull when you send air into the other. Note that you also have to let air out of the opposite port when moving.

Single acting have one port and can only push or pull. They usually have a spring to return the piston back to where it started when the pressure is gone.

You can use a double acting cylinder like a single acting one by just leaving one port unconnected.

Here is a dual action cylinder with 25mm bore and 100mm stroke that costs $15!!!

I’ve got a few of these and they are amazing. No air leaks around the seals. Wow.

Common port sizes are 1/4″ and 1/8″ NPT thread. You can get lots of plumbing stuff to screw into these ports at the hardware store, but you can also get quick connect fittings…


You can get these amazing quick connectors that screw into the ports on the actuators…

On the threaded side, make sure you get the right size (1/4″ or 1/8″ NPT) to fit the ports you have. These came with thread sealant already on the threads, so you just screw them in with a wrench. You can also put thread sealant on any threads if you really want no leaks.

On the other side you stick in a hose. I’ve been using 1/4″ OD which seams to be a standard. It looks like aquarium tubing (maybe it is?).

I make all my connections with this tubing…

I cut the hose with handy tool…

…although you could also just use scissors.

To make a connection, you just jam the hose into the hole. Seriously, that’s it. It seals tight.

To undo a connection, you just push in the plastic collar and pull the tube out again. How is this so easy?

Some of the quick connects come with little plastic lock rings that you can push under the collar to keep it from getting released accidentally.

There are lots of other fittings in this cheap and easy 1/4″ OD quick connect world. I’ve successfully used valves and elbows meant for water filters…

You can even get sweet check valves and regulators that fit this same quick connect system.

It is so damn easy!


Have a look at this thing….

It works just like a control valve on a backhoe – except with air! And they are so cute! And $10!!!!

This one is 5-way, 2 position. There are 5 ports – two that go to the ports on the cylinder, one that goes to the incoming pressure, and then two exhaust ports that let the air out of the opposite side of the cylinder. 2 position means the lever goes two ways – one way makes the piston push and the other makes it pull.

There are tones of these controllers with different style handles, or different numbers of ports, or different kinds of action.

You can also get electrically controllable ones…

…so now your Arduino can physically punch you in the face (rather than just metaphorically).

Pressure source

I got this schrader valve with an 1/8″ NPT thread so I could screw it directly into the pressure port on the controller….

This is the same kind of connector that tires use, so there are lots of options.

I used this bike pump…

… to make my pressure because it had a built in tank to hold extra air. I get about a dozen piston movements per pump-up. But you can use any bike pump- you might just have to pump more often. Or get your little bother to keep continuously pumping to keep things running.

Or get an electric pump like this…

Or use any crappy air compressor. Or make a pressure tank out of an old tire. Or blow into the the hose with your mouth (headache warning).

I know nothing

I know nothing about this stuff, but I got something working with just a few Amazon clicks. Please tell me everything I missed or got wrong in the comments!

Then show me the amazing things you’ve built with it!



  1. roberto venditti

    Awesome! I’m looking forward to seeing what you cook up :)

    As a nitpicky aside, I do not think you would call these “pneumatic hydraulics”; just “pneumatics”. As you noted, pneumatics are actuated using compressed gases while hydraulics use pressurized liquids.

    • bigjosh2

      As a nitpicky aside, I do not think you would call these “pneumatic hydraulics”; just “pneumatics”.

      I actually thought about this issue as I typed in the headline! I assume that most people do know what hydraulics are, so I went with the pattern “{descriptive adjective} {commonly known term}”, where the adjective specifically highlights why the assemblage is different from the common term. For example: “dry ice”. Every one knows what “ice” is, and “dry ice” is not ice – it is different from ice in that it is “dry”. “Pneumatic Hydraulics” are like normal hydraulics, except they are driven pneumaticly. Make sense?

      As a nitpicky aside, I do not think you should call “hydraulics” hydraulics at all. “Hydro-” means “water”, and so “hydraulics” properly refers to things like aqueducts and waterwheels rather than hoses and pistons filled with high pressure oil! :)

  2. Chris Robbie

    If you are interested, industrial instrumentation and process control uses this type of stuff all the time

  3. Marc Severino

    I was working graveyard shift as a kid back in 84, maintenance in a ground beef production facility and remember the grin I had seeing the air logic circuits in
    a cryovac packaging system. Imagine the size of a room to contain a pneumatic 8080 built on a massive circuit board and the debug issues.

  4. Sam S

    I highly recommend this ‘eBook’ by Automation Direct that will get you from 0-100 on pneumatics very quickly: (I have it bookmarked as “The Bible” in my pneumatics folder)

    Also, if you can get past the branding you should look for stuff there, I haven’t hesitated to use them for actual assembly line machines and they’re also cheap enough that I have a bunch of stuff at home just to screw around with.

  5. a. cynic

    I think the only purpose of the foamy things you can put in the exhaust ports is to muffle the sound. If you want to control the speed of the actuator you should use an actual air flow regulator inline with it.

  6. Robert Wm Ruedisueli

    You should check out hydraulic-pnumatic hybrid systems. These are things like modern power breaking and power steering.

    They are a little more complicated but add many of the stiffness behaviors of hydraulics into they system while still giving the simple power systems of pneumatic. By controlling various aspects of the systems you can create a best of both worlds custom tailored to your use. (Or just have fun experimenting to find how you can tune various types of actuation systems using robotics technology.)

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