Gears are used to transfer power between two rotating shafts, either by increasing or decreasing the angular speed, with a corresponding inverse change in the torque. If I want to do the same for linear motion, I see only two options in front of me:
Use Pascals law for liquids and connect pipe of varying diameters to multiply (or divide ) the force, as is done in car jacks, or,
Connect the input linear drive to a rotating shaft, connect it to a step-up or step down gear, and then convert rotary motion back to linear.
Hydraulic cylinders are kind of costly and keeping the fluid at a higher pressure is not quite convenient. Also using a linear-rotary-linear power transfer is easy to build but quite inefficient. Is there another way to do this?