10 replies to this topic

[chris_austin]

I've searched google, bricklink and brickshelf a few times and can't find anything but i'm certain of it's existence!  *alien*

I haven't got access to my old LEGO catalogues so I can't give you a set number but I swear there was a Technic set that had hydraulics instead of pneumatics! Early 2000's I think. Possibly a green/black colour combination.

[Sinner]

I think you're wrong... but I hope you're right!  X-D I have catalogs all the way to the mid 80s I have never heard of one. If it helps, this site is pretty good...

[HopelessMagic]

I don't think they ever used liquid. It just seems messy and I don't remember ever having a box of Lego come with a bottle of fluid to pour in it. There was a set from the 70s that had hydraulic in the name. Maybe this is what you're thinking of.

Hydraulic Set

[Freddie]

There's never been any Technic sets to use hydraulics. Actuation have always been limited to pneumatic power, and recently with the new linear actuators, also mechanical (plus the less obvious "Flex System").

It's not the Barcode Truck you're thinking off? That was green and black, and came out around the millenium. That was all electronic and mechanical, though.

[CP5670]

They used to call the dampened shock absorbers "hydraulic" pistons in the 1999 catalog. *wacko* That might have been what you saw. The 8446 crane truck had one and was green and black.

Edited by CP5670, 02 March 2008 - 06:34 PM.

[chris_austin]

Thanks for the Technica link, I found the set but it is pneumatic. 8846 (1999) http://isodomos.com/...x/8400/8446.php


Now I know the year, i'll look up the description. It wouldn't have stayed in my mind for no reason!


EDIT ^^^ post above: yep, that's exactly right.

Thanks everyone

Edited by chris_austin, 02 March 2008 - 09:06 PM.

[Blakbird]

 chris_austin, on Mar 2 2008, 04:35 AM, said:

I've searched google, bricklink and brickshelf a few times and can't find anything but i'm certain of it's existence!  *alien*

I haven't got access to my old LEGO catalogues so I can't give you a set number but I swear there was a Technic set that had hydraulics instead of pneumatics! Early 2000's I think. Possibly a green/black colour combination.

As you have discovered by now, they called the pneumatic dampers "hydraulics" at first.  I never figured out why they did this.  The pneumatic actuators at least function like hydraulics even if they use air for a fluid instead of oil (and are compressible).  But the dampers have nothing in common with hydraulics whatsoever.  I guess they just couldn't think of a good marketing term for them, or perhaps it was just a poor translation into English.

As someone who works with aircraft hydraulics for a living, I remember being pretty excited when I first saw this in the catalogs, and then pretty disappointed when I found out what they actually meant.  As if that wasn't bad enough, the first released dampers were very poor and broke after only a few cycles, but at least LEGO replaced them with an improved design for free.

Real hydraulic fluid is pretty caustic and certainly messy, so I doubt LEGO will ever go that route.

Eric

[Sinner]

 CP5670, on Mar 3 2008, 04:32 AM, said:

They used to call the dampened shock absorbers "hydraulic" pistons in the 1999 catalog. *wacko* That might have been what you saw. The 8446 crane truck had one and was green and black.

Well that makes sense... sort of.  :-D  Looking at my (Australian) catalog they don't call them that.

[Kamil]

 Blakbird, on Mar 3 2008, 05:45 AM, said:

As you have discovered by now, they called the pneumatic dampers "hydraulics" at first.  I never figured out why they did this.

Dampers work with hydraulics in reality but with pneumatics in Lego. Maybe this is the fact?

Kamil

[Blakbird]

 Kamil, on Oct 20 2008, 11:16 PM, said:

Dampers work with hydraulics in reality but with pneumatics in Lego. Maybe this is the fact?

Yes, you can make a damper work with either hydraulics or pneumatics, but they work somewhat differently.  In both cases, the output of the fluid (air or oil) is metered through an orifice.  The smaller the orifice, the slower the fluid can escape, which controls the rate of the damper.  Air is compressible so changes volume considerably under load.  For this reason, only relatively small loads can be supported without a large displacement.  Hydraulic oil is (mostly) incompressible so it can react very large loads immediately.  This is what is used in an automobile shock absorber, or even one for a radio control car.

The term "hydraulic" refers to using incompressible oil, so it really cannot apply to the Lego dampers.  I think they just wanted a term to make sure people knew it was not the same old pneumatic system.

[Buttons]

If I am correct I remember seeing a post on TechnicBRICKs that was talking about hydraulic cylinders. Take a look, If I was wrong it is still a great little website to know about if your into anything technic.