NOVELTY - A housing (5) encloses one of two perpendicular input shafts (1), while an element is connected with the other input shaft (2). When the housing or element rotates clockwise or counter clockwise, one of the one-way clutches (7A,7B,13A,13B) locks the associated input shaft, while the bevel gears (6A,6B,6C,9A,9B,9C) mesh together to rotate the shaft clockwise.    USE - Rotation motion conversion device for producing uni-directional rotation as output from any three-dimensional motion as input. Can also be used in a power production system (Claimed) for e.g. wave power generation. Can also be used in power production system using water streams found in river or part of sea located offshore or close to coast, or in power production system for vessels e.g. sailboats, or small power production systems for operating low power electronic or electrical devices e.g. global positioning system markers for tracking wild animals, cell phones. Power production system can also be used in places where lot of people are walking, such as stations and airports, in locations where instability can be used to produce power, in kitchen or floor areas in homes, and in factories, and also be used in toys e.g. skateboards, or disabled persons.    ADVANTAGE - The device allows two input rotation motions around two perpendicular input shafts to provide rotation motion around output shaft in single direction, enabling device to adapt to power production systems for wide range of applications. Power production system is environment friendly to use on water streams and collect energy from streams, preventing harm to e.g. aquatic wildlife. Parts of device and power production system need not be totally immersed in water, avoiding parts corrosion and improving parts maintenance. Power production system, when used on vessels, allows batteries to be left on-board, leaving more space for other loads and giving user more time spent on other activity without requiring user to go into port to load batteries. Single direction rotation can also be performed by e.g. factory workers, with reduced risk of repetitive strain injury, or by skateboards or disabled persons.    DESCRIPTION OF DRAWING(S) - The drawing shows the elevation view of a rotation motion conversion device.    Input shafts (1)    Horizontal support (4)    Housing (5)    Bevel gears (6A,6B,6C,9A,9B,9C)    One-way clutches (7A,7B,13A,13B)