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Subject: 
Re: pneumatic cylinder: why not hydraulic ??
Newsgroups: 
lugnet.technic
Date: 
Tue, 6 Apr 2004 18:21:00 GMT
Viewed: 
2389 times
  
In lugnet.technic, Chris Masclet wrote:
I' ve read a long time ago something like this: LEGO pneumatic cylinder
cannot be use as hydraulic cylinder.

Is anybody can explain me why ?? May be we can' t use water with cylinder
(may be cause of corrosion) but what about silicone oil ?? or something like
that....

I can think of a few concerns that would need to be answered before using a
pneumatic cylinder as a hydrolic cylinder:

1. will the seals work properly

I'd be concerned that the lubricant would get washed away by water, so the only
way to prevent that from happening would be to use the same lubricant as the
compression agent, which could pose its own problems.

2. will the cylinder itself stay intact

The tubing should pop off pretty easily compared to blowing out the cylinder, so
I'm guessing this wouldn't be a problem.

3. will the hydrolic compression agent corrode the cylinder components

The plastic shouldn't be a problem, but the metal parts are hard to say.  If
they haven't rusted after a few years, you might be okay, especially if you use
distilled water.

4. how does the compression agent get in

I know that the compression agent gets in through the hand-actuated pump
cylinder, which means that the only way to get hydrolic compression agents in
would be to immerse the pump in a bucket of the compession agent...which would
mean having to immerse your hand in the same bucket to actuate the pump.  Blech.

5. how does the compression agent get out

Since you have to pump the system full of air to make the cylinders work, the
air clearly has some means of escaping the system.  If you use water or oil,
it's going to come spurting out all over the place.  Do you really want that?

6. will the compression agent travel through the tubing

The more viscous the agent is, the more it will resist travelling through the
small tubes, and the more likely you are to pop a tube loose.  Water will travel
slower than air, and oil will travel even slower than water.

The other thing to consider is if using them as hydrolic cylinders would even
help.  Many common hydrolic cylinders that you see in everyday life are used to
resist movement, not cause it.  Think of automatic door closers (three cylinders
are used for resistance to control the opening speed, closing speed, and
latching speed) and hydrolic shock absorbers.  I'm guessing you might be able to
get higher PSI with hydrolics, but the friction-fit tubing might not allow you
to reach the full potential of the cylinders themselves.



Message has 1 Reply:
  Re: pneumatic cylinder: why not hydraulic ??
 
purpledave@maskofdestiny.com (Purple Dave) wrote in <HvrHn0.Cpw@lugnet.com>: (...) I'd add 7. if you used hydraulics, a cylinder would extend or retract fully with one stroke of the pump. The resistance the cylinder encounters is transmitted to the (...) (20 years ago, 7-Apr-04, to lugnet.technic)

Message is in Reply To:
  pneumatic cylinder: why not hydraulic ??
 
Hi everybody, I' ve read a long time ago something like this: LEGO pneumatic cylinder cannot be use as hydraulic cylinder. Is anybody can explain me why ?? May be we can' t use water with cylinder (may be cause of corrosion) but what about silicone (...) (20 years ago, 6-Apr-04, to lugnet.technic)

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