GazK

Hi all. I've been working for some weeks on building a working train pantograph - I'm happy with the design, which closely mimics the operation of the main UK type. But I'm having trouble getting my compressor to provide enough oomph to raise it - it's quite a large load, given it has to raise the whole pan up at a large mechanical disadvantage (just like the real thing). I started with a 4 pump compressor, driven by two hard-coupled L motors driving the pumps in 2 groups of 2 through 24/12. Initially it worked, but as time went on it got weaker - which I don't understand - and often would work on the first lift, but on subsequent lifts the pump would audibly "fade" once initial pressure is reached. I tried a few things; the compressor is now run off a 9V mains supply, to avoid going through batteries. I've now added two more pumps, and I've tried decoupling the two motors. None of those measures improved things. Here is a video of the current setup: Can anyone advise what I'm doing wrong?

I know what you mean - the vehicle is the one item in the book I have no intention of building - not after I motorised my off-roader! While we're at it could anyone tell me what the long thin rods in this photo are called? I need to order those as well:

Quite right, its the forbidden lego book wot I got... the videos are great, its hard to visualise how the mechanisms work from still images.

aaah, lovely, thanks. I was searching on "gear" and "liftarm" - no wonder I couldn't find it.

Could anyone please help me with the name and/or lego ID of this piece? I got an extreme lego book for my birthday and I need to order a couple. None of the obvious search terms or google images have helped.