Pneumatics General Discussion

[Epic Technic]

Are there any pneumatic engines that run at a reasonable rpm without modified parts?

Not amazing RPM but it's possible. I would highly recommend opening your cylinders and replacing the grease with some better type of lubricant, even plain old vegetable oil works well for me.

[MSc Shobaki]

Are there any pneumatic engines that run at a reasonable rpm without modified parts?

Roughly between 170-220 rpm unmodded. 250-280 lubricated with silicon spray

[nerdsforprez]

I finally got around to reading this thread. I love pneumatics and have used them successfully in several build s. Personally I would love to see some truck trials with only pneumatic engines. That would allow some muddin and boggin competitions not really possible with current truck trials because of electronics. Also.... Surprised not to see the work of Alex Zorko (lpepower) mentioned here. I think he had some of the best lpes available.

[Karle]

I'm interested in building the 8275 bulldozer. Has anyone built one with pneumatics?

[A Gallifreyan Cat]

A quick google search reveals that someone has:

[Epic Technic]

Does anyone has a compact method of attaching two of the new (the ones without the brick base) medium sized cylinders without the expensive cylinder bracket? I sort of need this for TC9 so anything is dearly appreciated

[Saberwing40k]

Does anyone has a compact method of attaching two of the new (the ones without the brick base) medium sized cylinders without the expensive cylinder bracket? I sort of need this for TC9 so anything is dearly appreciated

I do, as a matter of fact.

Pneumatic cylinder bracket by Saberwing007, on Flickr

step2 by Saberwing007, on Flickr

the track link can be replaced with a 3L thin liftarm if so desired, but I prefer the track link as it is thinner than a liftarm, so allowing a better connection. However, there is a caveat. when incorporating this assembly into a structure, one should orient the two cylinder so that the force applied is more likely to push the cylinders into the bracket, as the inlets could snap if enough pressure were applied to them.

[Epic Technic]

Thanks a lot! I'll try it.

[Alasdair Ryan]

Has anyone created a moc with servo controlled pneumatic steering like the image below,If so how well did it work?

I am thinking of having a servo control the "direction" of both cylinders to control the steering of the axle.

I would also like the ability to change the direction of each side (crab steer,all wheel steer) using another servo or gearbox.

[syclone]

I suppose there will be problems of coordination between the two pistons.

Also a problem is that the pneumatics don't have proportional control

Edited March 1, 2016 by LXF

[Alasdair Ryan]

I suppose there will be problems of coordination between the two pistons.

Yes there is going to be some difference,that is a shame.

Also a problem is that the pneumatics don't have proportional control

Does that not depend on the construction of the servo powering the valve?

[AkiyamaWataru]

As LXF said you dont get proportional steering. With a servo and a valve its only posdible to control the speed with which the piston extends or retracts. It is not possible to control the position. (Except the extreme positions)

[lcvisser]

Can't you use only one cylinder and use a beam to connect left and right? That would solve the coordination problem. I don't see why you would have to control left and right on a single axis individually.

[Corvette3]

Yes there is going to be some difference,that is a shame.

How about a 13l beam on the lower pins?

Oops ninja'd

Edited March 1, 2016 by Corvette3

[Alasdair Ryan]

Yes I could do that,how well does it work in terms of controlling the steering?

[DrJB]

In real-life applications, dozers suffer from what's called 'straight tracking', where both left/right tracks are not always running at the same speed (at least for hydro-static drives). As a result, most dozers would tend to steer randomly left/right, depending on soil conditions. In such case, what is done is to define one track (left or right) as a master, and the other as a slave. The user input (throttle) always controls the master track, and the electronics ensure the slave track is always keeping-up with the master. Neat implementation of sensors, hydraulics and computer code.

[Jim]

In real-life applications, dozers suffer from what's called 'straight tracking', where both left/right tracks are not always running at the same speed (at least for hydro-static drives). As a result, most dozers would tend to steer randomly left/right, depending on soil conditions. In such case, what is done is to define one track (left or right) as a master, and the other as a slave. The user input (throttle) always controls the master track, and the electronics ensure the slave track is always keeping-up with the master. Neat implementation of sensors, hydraulics and computer code.

Interesting!

[LucyCol]

In real-life applications, dozers suffer from what's called 'straight tracking', where both left/right tracks are not always running at the same speed (at least for hydro-static drives). As a result, most dozers would tend to steer randomly left/right, depending on soil conditions. In such case, what is done is to define one track (left or right) as a master, and the other as a slave. The user input (throttle) always controls the master track, and the electronics ensure the slave track is always keeping-up with the master. Neat implementation of sensors, hydraulics and computer code.

Wished they'd had this in my day used to spend all day pulling on one track to keep a straight line, main problem was the pins that held the track links together wore unevenly, only computer we had was the one on top of my neck

Edited March 1, 2016 by LucyCol

[Epic Technic]

Does anyone know of some good pneumatic steering systems and possibly ones with return to center steering?

[Limga]

44 minutes ago, Epic Technic said:

Does anyone know of some good pneumatic steering systems and possibly ones with return to center steering?

I tried some, but didn't made any pictures. It is possible to have a return to center steering. Still, no proportional control. I will try to rebuild it soon. 

[Milan]

1 hour ago, Epic Technic said:

Does anyone know of some good pneumatic steering systems and possibly ones with return to center steering?

Did you check axle collection thread? Maybe you'll have some luck there...

[mocbuild101]

1 hour ago, Epic Technic said:

Does anyone know of some good pneumatic steering systems and possibly ones with return to center steering?

I know of some with linear actuators, but I don't think they could be adapted for pneumatics .

I might try to make one myself...

[degenerate]

Hey,

Last time I played with pneumatics was some 18 years ago with the 8462 tow truck, don't have any experience with the V2 parts. 
I remember hoses flying off their connections due to high pressure, is this fixed with the V2 ones?
I plan on building an excavator where I'll have 3 small pumps run by a PF motor, is there some part that dumps air when the pressure reaches a certain level or does the pumps have a similar feature built in nowadays?

Cheers

[Leonardo da Bricki]

@degenerate  There are no functions included like that, so you either have to monitor the pressure yourself, or it is possible to make a pressure shut-off valve using a small cylinder, a red or blue rubber band, and a PF switch. Sariel's handy-dandy Unofficial Lego Technic Builder's Guide 2nd Edition will give you all you need to know. My pneumatic parts are currently in use, otherwise I could show you how the set-up works. Sorry.

[aminnich]

Probably a terrible idea, but has anyone ever ran water through their pneumatics? I would think water does my compress as easily as air, so the cylinders could withstand more pressure. 

I don't know, what do you think?