love.physics.newGearJoint
Create a GearJoint connecting two Joints.

The gear joint connects two joints that must be either prismatic or revolute joints. Using this joint requires that the joints it uses connect their respective bodies to the ground and have the ground as the first body. When destroying the bodies and joints you must make sure you destroy the gear joint before the other joints.

The gear joint has a ratio the determines how the angular or distance values of the connected joints relate to each other. The formula coordinate1 + ratio * coordinate2 always has a constant value that is set when the gear joint is created.
joint = love.physics.newGearJoint( joint1, joint2, ratio, collideConnected )
joint1 Joint The first joint to connect with a gear joint.
joint2 Joint The second joint to connect with a gear joint.
ratio (1) number The gear ratio.
collideConnected (false) boolean Specifies whether the two bodies should collide with each other.
joint GearJoint The new gear joint.