Moving motion transmition

[mindoverflow]

Hello,

I need to feed a linear moving device with rotative force. Then i need your advice about such a system.

I came up with the solution shown on the sketch, wich consists of a carved rail in a long rod or tube attached to a motor, and a gear sliding over the rod and hooked to the rail. The gear is connected to the moving device somehow with bearings to insure linear movement and connected to an other gear trought tooths side.

But I'm not sure about the friction effect on both linear and circular motion (planing for less than 3000 rpm).

Anyone have a better idea?

Thanks.