CVT- Continuously Variable Transmission

Why CVT? CVTs work and how they improve performance,etc...

a) What's the purpose of CVTs? To vary the transmission ratio continuously.
b) How do CVTs work?  It depends on the CVT type:
  1. Friction CVTs vary the radius of the contact point between two rotating objects, thus the tangential velocity;
  2. Hydrostatic CVTs vary the fluid flow with variable displacement pumps into hidrostatic motors;
  3. Ratcheting CVTs vary the stroke of a reciprocating motion, which is connected to a free-wheel, resulting unidirectional rotation.
c) How do CVTs improve efficiency? They allow the engine to operate allways in it's optimum R.P.M., whatever the vehicle's speed.
d) What are the benefits of operating in the optimum R.P.M.? 1.lower consumption; 2.less greenhouse gas emissions; 3.better performance;
e) CVT is the ideal transmission, so why are there so few CVT cars? The existing inventions are based on 1.friction, 2.hydrostatic, 3.ratcheting which are all mechanical systems with inherent limitations, (compared to traditional transmissions).
f) So, how to extract the full CVT potential? A conceptual innovation is the only way out. Although, research continues improving the friction CVTs and ratcheting CVTs, these efforts are acomplished by expensive high tech materials and precision manufacturing. This is to overcome the inherent limitations of these concepts (friction and ratcheting).
How do CVTs work?
How do CVTs  improve performance?
Other instructive websites:
Basic knowledge on "how do transmissions (in general)work":
Recent CVT vehicles and research:
Historical info on CVT inventions:
Further questions, answers, links:

  [created: 16 Mar 2003, updated: 19 Set 2008 ]  [ designed by ]