BASICS OF TRANSMISSION
WHAT IS CONTINUOUSLY VARIABLE TRANSMISSION
HISTORY OF CVT
CVT COMPONENTS & DESIGN
WHY USE CVT…..?
BASICS OF TRANSMISSION
The job of the transmission is to change the speed ratio
between the engine and the wheels of an automobile.
The transmission uses a range of gears -- from low to high -- to
make more effective use of the engine's torque as driving
conditions change. The gears can be engaged manually or
CVT is an advanced technology of automatic transmission.
Unlike traditional automatic transmissions, continuously
variable transmissions don't have a gearbox with a set
number of gears.
Varies the transmission ratio continuously.
Shifts automatically with an infinite number of ratios.
A continuously variable
(also known as single-speed
automatic, variable pulley
transmission, or in case of
motorcycles, a twist-and-go) is
a transmission that can change
seamlessly through an infinite
number of effective gear
ratios between maximum and
WHAT IS CONTINUOUSLY
VARIABLE TRANSMISSION (CVT)
Leonardo da Vinci sketches is the basis for the first
continuously variable transmission in 1490.
First patent for the CVT Transmission was made by Daimler &
Benz in 1886.
The first workable belt driven CVT was designed and built by
the Dutchman Huub van Doorne in 1958.
In Early 1990's Nissan introduced CVT in their Nissan March
2004 - Ford begins offering a CVT .
HISTORY OF CVT
THREADING NUT &
HOW CVT WORKS ?
CVT consist of two adjustable conical pulleys driven by V-belt.
One of the pulley is driven by Engine and other is coupled
The distance between pulleys is inversely proportional with
velocity ratio of belt drive.
Hence by adjusting the distance between pulley we can
obtain desired no. of gear ratio without stepped gears.
How A CVT Works .mov.mp4
CVT has been classified into following types:
1. Pulley Based CVTs or Reeves drive
2. Toroidal or roller-based CVTs (Extroid CVT)
3. Hydrostatic CVTs
4. Infinitely Variable Transmission (IVT)
5. Cone CVTs
In this most common CVT system , there are two V-
belt pulleys that are split perpendicular to their axes of
rotation, with a V-belt running between them.
1. PULLY BASED CVT’S
Toroidal CVTs are made up of discs and rollers that transmit
power between the discs.
2. TOROIDAL CVT’S
Hydrostatic transmissions use a variable displacement
pump and a hydraulic motor. All power is transmitted
by hydraulic fluid.
3. HYDROSTATIC CVT’S
A subset of CVT designs are called infinitely variable
transmissions (IVT or IVTs)
4. INFINITELY VARIABLE
A cone CVT varies the effective gear ratio using one or more
WHY USE CVT……..?
8.8 sec. 11.9 sec.
• The Continuously Variable
Transmission (CVT) proved 35%
more efficient than the Manual
• With same car and engine, the
CVT takes only 75% of the time to
accelerate to 100km/h, compared
to the MT.
Ride on Lawn Mowers
There is improved acceleration due to the lower power loss
Step less transmission.
Delivers maximum torque.
Provides a smoother ride than automatic transmission.
Adapts to varying road conditions and power demands to
allows for a better ride.
This improves fuel economy and reduce exhaust emissions.
There are 25% fewer moving parts to a CVT transmission
Belt-driven CVTs (VDP system) have a limited amount of torque.
Transmitting motion by friction causes greater wear.
Require special oil and other materials.
Becomes Jerky in automobile applications at slow speeds.
New technology so there are limited people that understand the
operations with in a CVT.
CVT can be improved with research on the belt design
permitting use in high performance vehicles.
Hybrid vehicles will also feature with this type of transmission
Electric motors can avoid the low speed/ high torque
problems often associated with CVTs, through an
innovative double-motor system.
Kia recently tested a system where the CVT allows the
engine to run at constant speed and the motor allows the
engine to run at constant torque independent of driving
In the future a major amount of cars will feature CVT .
Today, only a handful of cars worldwide make use of CVTs,
but the applications and benefits of continuously variable
transmissions can only increase based on today’s research and
As automakers continue to develop CVTs, more and more
vehicle lines will begin to use them. As development
continues, fuel efficiency and performance benefits will
inevitably increase; this will lead to increased sales of CVT-
Increased sales will prompt further development and
implementation, and the cycle will repeat ad infinitum.