2. CONTENTS
โข Introduction
โข Classification of Geneva Mechanism
โข Working of Geneva Mechanism
โข Advantages of Geneva Mechanism
โข Disadvantages of Geneva Mechanism
โข Application and Uses
โข Future scope
โข conclusion
3. INTRODUCTION
The Geneva drive or Maltese cross is a gear mechanism that translates a
continuous rotation into an intermittent rotary motion. The rotating drive
wheel has a pin that reaches into a slot of the driven wheel advancing it by
one step. The drive wheel also has a raised circular blocking disc that locks
the driven wheel in position between steps.
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4. CLASSIFICATION OF GENEVA
MECHANISM`
๏ EXTERNAL GENEVAMECHANISM
In this type of mechanism, the Geneva cross is connected with cam drive
externally which is the most popular and can withstand higher mechanical
stresses. The driver grooves lock the driven wheel pins during dwell.
During movement, the driver pin mates with the driven-wheel slot.
5. ๏ INTERNAL GENEVAMECHANISM
In this type of mechanism, the Geneva cross and cam drive are connected
internally in the closed box. The driver and driven wheel rotate in same
direction. The duration of dwell is more than 180ยบ of driverrotation.
6. ๏ SPHERICAL GENEVAMECHANISM
In this type of mechanism, the Geneva cross is in spherical shape and cam
drive are connected in externally, which is extremely rare . The driver and
driven wheel are on perpendicular shafts. The duration of dwell is exactly
180ยฐ of driver rotation.
7. Working of Geneva Mechanism
๏ In the most common arrangement, the driven wheel has four slots and thus
advances by one step of 90 degrees for each rotation of the drive wheel. If
the driven wheel has n slots, it advances by 360ยฐ/n per full rotation of the
drive wheel.
๏ Genevas are also combined with variety of other mechanism , such as four
bar linkages , clutch-brake combinations , non โcircular gears etc to modify
the motion curves and dwell motion ratios obtained from pure Geneva.
8. Advantages of Geneva Mechanism
โข Geneva mechanism may be the simplest and least Expensive of all
intermittent motion mechanisms.
โข They come in a wide variety of sizes, ranging from those used in
instruments, to those used in machine tools to index spindle carriers
weighing several tons.
โข They have good motion curves characteristics compared to ratchets, but
exhibit more โjerkโ or instantaneous change in acceleration, than better
cam systems.
9. Disadvantages of GenevaMechanism
โข The Geneva is not a versatile mechanism and producejerk.
โข The ratio of dwell period to motion is also established once the no of dwells
per revolution has been selected.
โข All Geneva acceleration curves start and end with finite acceleration &
deceleration.
10. Applications and uses
โข It is applicable in the production industries and in automobile industries for
mass production.
โข Modern film projectors may also use an electronically controlled indexing
mechanism or stepper motor, which allows for fast-forwarding the film.
โข Geneva wheels having the form of the driven wheel were also used in
mechanical watches, but not in a drive, rather to limit the tension of the
spring, such that it would operate only in the range where its elastic force is
nearly linear.
โข Indexing tables in assembly lines, tool changers for CNC machines, and so
on.
11. FUTURE SCOPE
๏ถ Design optimization of a Geneva mechanism for internal combustion
engine application.
๏ถ Bottle Indexing and Filling Mechanism.
๏ถ It Can be used in Pen Changed Mechanism in Plotters.
๏ถ It has a great scope in automated sampling industries.
12. Conclusion
Geneva drive indexing mechanism converts the continuous motion of the
driver wheel into intermittent rotary motion of the gear. Cam with pin
arrangement integrated with Geneva drive. Input shaft having driver wheel
at one end and cam drive at the other end. Geneva drive and gears are
mounted on the output shaft. By cam with Geneva drive arrangement the
continuous motion of the driver wheel converts into intermittent motion of
gear and chain arrangement. Due to gear rotation the conveyor belt moves
and thus mechanism proves its significance.
