Design for a Level Metal Elevator

[Epigen]

I am a third year chemical engineering student and don't have much experience in the mechanical stream so I was hoping someone here could help me.

At the moment I have an apparatus that consists of a sheet of metal with four syringes sticking through (metal sheet is horizontal, syringes are vertical with plungers sticking up.) I need to be able to push these syringes down at the same speed (each will have the same substance inside.) I am thinking of a way to make an elevator that I can put weights on top of (to increase/decrease speed) - it would essentially be a second sheet of metal that rests horizontally on top of the plungers with metal rods on each side that it can slide on (there will be holes on each side of the sliding plate.) I was trying to think of a way that I could have two metal rods on each side of the plate and the metal would slide down and remain level. However, when I make the whole into the sheet and test the sliding down the metal rod it happens in jerks because of friction, and I need it to move smoothly.

(Hope what I wrote above makes sense)

So, overall, I'm trying to think of a way to reduce this friction between the sliding plate and the two vertical rods it slides on. Or if there's a better way to do this - I'm all ears!

Another thing, does anyone know of a lubricant that works well between two metal surfaces?

[PinkertonD]

I am guessing this falls under the topic of Homework, but since you are trying to make something I am tempted to side-step that restriction here.

Your basic "thing" is pretty close. Part of the reason it jerks is that there is no means of maintaining the sliding plate parallel with the base plate during the travel. Also the force to overcome the beginning movement of the syringe plungers is probably higher than the force required to maintain a steady flow out of the syringes once moving.

So, first things first, in the final project, how will you be pushing the top plate down? Fingers, air cylinder, electric motor, 4 large bricks, car jack?

We can get to the other issues in a while.

Dave
Generally, I will not give you the answer to your question, but I *will* guide you into discovering how to solve this yourself.

[zeke]

What you need is a parallel plate mechanism. Two cylinders won't do it
Try googling "car jack mechanism" and you will probably get your answer.
Also, you might look into the trunk of your car to see the real thing.