1. CONTINUOUSLY VARIABLE TRANSMISSION - CVT

2. Overview of a CVT Varies the transmission ratio continuously.
Shifts automatically with an infinite number of ratios.
Seamless power delivery.
Constantly changes its gear ratio to optimize engine efficiency.
Allows the engine to rev almost immediately to deliver maximum torque.

3. A Timeline of CVT Innovation
da Vinci sketches a stepless continuously variable transmission
First toroidal CVT patent filed
Adiel Dodge receives U.S. patent for toroidal CVT
Fully automatic transmission based on planetary gear system introduced.
Daf (of The Netherlands) produces a CVT in a car.
Subaru Justy GL is the first U.S.-sold production automobile to offer a CVT.

4. CVT DESIGN GOALS Truly continuously variable
Transmit torque both forward and backward
Able to transmit high torque levels
Able to shift under load
Computer control not required
Mechanical looses are less

5. Working of CVT
CVT transmission operates by varying the working diameters of the two main pulleys in the transmission.
When actuated, the cylinder can increase or reduce the amount of space between the two sides of the pulley
A CVT operates on three main mechanical components : flyweights or cams, springs, and ramps

6. CVT WORKING MODEL

7. Major parts of CVT

8. Types of CVT Variable-diameter pulley (VDP) or Reeves drive
When the two cones of the pulley are far apart , the belt rides lower in the groove.
When the cones are close together, the belt rides higher in the groove.
This type of CVT may use hydraulic pressure, centrifugal force or spring tension to create the force necessary to adjust the pulley halves.

9. Toroidal CVT
This type of CVT replaces the belts and pulleys with discs and power rollers.
One disc connects to the engine. This is equivalent to the driving pulley.
Another disc connects to the drive shaft. This is equivalent to the driven pulley.
They spin around the horizontal axis and tilt in or out around the vertical axis, which allows the wheels to touch the discs in different areas.

10. Hydrostatic CVTs
Hydrostatic transmissions use a variable displacement pump and a hydraulic motor.
That uses variable-displacement pumps to vary the fluid flow into hydrostatic motors.
They have the advantage that the hydraulic motor can be mounted directly to the wheel hub.

11. Cone CVT
In a CVT with oscillating cones, the torque is transmitted via friction from a variable number of cones (according to the torque to be transmitted) to a central, barrel-shaped hub.
A particular characteristic of the Warko is the absence of a clutch.

12. Push Belt
In the variator, torque or power is transmitted from the primary to the secondary pulley via friction between the push-belt elements and the pulley sheaves.
The belt needs to be very stiff in the pulley's axial direction in order to make only short radial movements while sliding in and out of the pulleys
The push-belt rings are mainly subjected to bending and tensile stresses.

13. Advantages Disadvantages
Decreases engine fatigue
Allows for an “infinite” number of gear ratios, maintaining the engine in its optimum power range
More mechanically efficient than Automatic transmissions.
Greater fuel efficiency than both manual and automatic transmissions.(Fuel savings of more than 17% have been achieved).
Cheaper and lighter than Automatic trans.
Smooth, responsive and quiet to drive
CPU can be configured to suit a wide range of driving modes and styles.
Limited torque capacity when compared w/manual transmissions.
Larger and more costly than manual transmissions.
Slipping in the drive belt or pulleys.
Complacency by the automobile industry, unwilling to discard billions of dollars in development in MT & AT’s.

14. IMPLEMENTATION Adaptable for trucks Audi A4 TDI Military vehicles
Heavy construction equipment
Bicycle
Motor cycles
Industrial machinery
any type of motor
IMPLEMENTED IN
Audi A4  TDI
Audi A6 2TDI
Ford Escape Hybrid 2.3
Ford Focus C
Honda Civic Hybrid 
Honda HR-V 1.6
Honda Insight 1.0
Nissan Murano 3.5
Nissan Primera 2.0
Nissan Serena 2.0
OPEL VETERA
Saturn VUE 2.2/3.5
Toyota Prius 1.5 4cyl 2

15. CONCLUSION
IT IS ADVANTAGEOUS TO USE A CVT INSTEAD A MANUAL TRANSMISSION.
THIS IS MAINLY BECAUSE THE ENGINE WILL OPERATE ALWAYS ON THE OPTIMUM REGIMES AND THROTTLE-POSITIONS ADAPTED TO THE VARYING ROAD CONDITIONS AND POWER DEMANDS.

16. REFERENCES Fischetti Mark . "No More Gears".
“Popuplar Mechanics” by MC COSH

17. Thank You