This document summarizes information about continuously variable transmissions (CVTs). It discusses how CVTs can operate over an infinite range of gear ratios compared to fixed gear transmissions. CVTs allow the driving shaft to maintain a constant speed over a variety of output speeds. They provide better efficiency than other transmissions by allowing operation at the most efficient RPM. Applications mentioned include small tractors, combine harvesters, and machine tools. The document also discusses principles of self-aligning CVTs and methods to increase the range of regulation, including using multiple variators, variator-gearbox combinations, and variators with epicyclic mechanisms.

1. Sunil sharma
suraj karn prakash
susheel pal
t.aslam
d.thamotharan
Submitted by:
PrinciplesOfSelfAligning And
MethodsOfIncreasingRangeOf Regulation.
Department of manufacturing engineering
ANNAMALAI UNIVERSITY
BATCH’B’
Viii semester

3. INTRODUCTION
 A continuously variable transmission
(CVT) is a transmission that can change
steplessly through an infinite number of
effective gear ratios between maximum
and minimum values.
 This contrasts with other mechanical
transmissions that offer a fixed number of
gear ratios.
 The flexibility of a CVT allows the driving
shaft to maintain a constant angular
velocity over a range of output velocities.
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4. ADVANTAGES
 This can provide better efficency than other
transmissions by enabling the operation to
run at its most efficient revolutions per
minute (RPM) for a range of operating
speeds.
 Alternatively it can be used to maximize the
performance of a machine by allowing the
machine to turn at the RPM at which it
produces peak power. This is typically
higher than the RPM that achieves peak
efficiency.
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5. APPLICATIONS
 Many small tractors for home and garden
use have simple rubber belt CVTs
 Combine harvesters have CVTs. This
allows the operator to slow or accelerate as
needed to accommodate variations in
thickness of the crop.
 Some drill presses and milling machines
contain a pulley-based CVT where the
output shaft has a pair of manually-
adjustable conical pulley halves through
which a wide drive belt from the motor
loops.
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6. PRINCIPLES OF SELF
ALIGNING
initial pressure
produced by the
weight of a power
disc is very small

7. Let P= initial friction force produced between disc and roller

8. STEPLESS REGULATION
CAN BE CARRIED OUT BY
 ELECTRICAL SYSTEM
 ELECTRONIC SYSTEM
 HYDRAULIC SYSTEM
 MECHANICAL FRICTION DRIVE AND
PRESSURE VARIATOR

9. ADVANTAGES OF STEPLESS
REGULATION SYSTEM:
 No loss in speed
 Can arrange speed adjustment without
stopping machine.
 It reduces time losses and very useful in
automatic tool
 Hydraulic drive avoids speed fluctuation

10. methods of Increasing range of
regulation
1.BY USING MANY
VARIATORS
Only belt
drive and
gear drive
is used

11. CHARACTERISTICS
 Here we donot use the full possibility of
3 variators.
 Too many speeds can be repeated.
 The system is not very much used
because we donot get many number of
speed.

12. 2.COMBINATION OF
VARIATORS WITH GEAR BOXES

13. CHARACTERISTICS
 Shaft 1st can have one constant speed.
 Shaft 2nd have a particular range of speeds.
 About shaft 3rd, three different speeds reduced
by gear ratios corresponding to any point on
2nd staff.
>>DIFFICULTIES
If the initial range is big then the ratio cant be
achieved as the gear box has its influence

14. 3.VARIATORS WITH
EPICYCLIC MECHANISM:

15. >DISADVANTAGES
>complicated to manufacture.
>can not be used in high speed.
>low efficiency if high range is produced.
>used only in feed drives.

16. ACKNOWLEDGEMENT:
>Design of Machine Tools, Basu S.K., and
Pal D.K.
>Machine tool Design and Numerical
Control, Metha N.K.
>GOOGLE SEARCH ENGINE

17. THANK YOU