Internal Geneva Mechanism
Aim: To perform the Motion analysis of the Internal Geneva Mechanism.
Description:
Geneva Mechanism (GM), or some time calls Maltese cross, is a linkage that supplies a discontinuous (intermittent) rotary motion, and it is commonly used in both high and low-rotating speed machines.
APPLICATIONS & USES
• STEPPER
• MECHANICAL WATCHES
• PLOTTERS
• CNC MACHINE
• IRON RING CLOCK
• Modern film projectors may also use an electronically controlled indexing mechanism or stepper motor, which allows for fast-forwarding the film.
• Geneva wheels having the form of the driven wheel were also used in mechanical watches, but not in a drive, rather limit the tension of the spring, such that it would operate only in the range where its elastic force is nearly linear.
• Geneva drive include the pen change mechanism in plotters, automated sampling devices
• Indexing tables in assembly lines, tool changers for CNC machines, and so on.
• The Iron Ring Clock uses a Geneva mechanism to provide intermittent motion to one of its rings.
Objective:
• To create 3D models for driver and driven wheels of the Internal Geneva Mechanism from the drawings.
• To create the Assembly of the Internal Geneva Mechanism.
• To analyze the motion of the Internal Geneva mechanism assembly (with precision and without precision).
• To plot a graph of Contact force (between driving and the driven wheel) as a function of time.
• To plot a graph of angular displacement of the driven wheel.
Figure: Flow of the project.
3D CAD Models
PRECISE CONTACT SETUP
• 10 rpm with precise contact
• 20 rpm with precise contact
Steps followed:
• 3D models are created on the basis of given drawings
• The individual parts are assembled together on the basis of the dimensions of the drawings.
• The motion of the wheels is constrained to rotate about their respective axes.
• A motor is installed at the axis of the driving wheel at the given rpm.
• Contacts are established between the wheels.
• After running the motion analysis, the required plots are plotted.
• The Precision contact option is used for other cases and motion is analyzed again with their respective plots.
Results:
CASE 1: Driver rotating at 10 rpm
• Contact force between driver and driven wheels
• Angular displacement of the driven wheel
• Angular velocity of the driver
Video link:
https://drive.google.com/file/d/1S1oQjvTHfP271WFyJ9w94umfVBFkqq0n/view?usp=sharing
CASE 2: Driver rotating at 10 rpm with precise contact on
• Contact force between driver and driven wheels
• Angular displacement of the driven wheel
• Angular velocity of the driver
Video link:
https://drive.google.com/file/d/1ph-u5HwSwAvn0VrPP4GO74YicySzlTuW/view?usp=sharing
CASE 3: Driver rotating at 20 rpm with precise contact on
• Contact force between driver and driven wheels
• Angular displacement of the driven wheel
• Angular velocity of the driver
Video link:
https://drive.google.com/file/d/13wFLO_NRWrqCvKhZ-GsQdPY8mhVsoTNQ/view?usp=sharing
Conclusions:
• Contact Force between the driver and the driven wheels
In precise contact, forces are more and as rotating speed will increase the contact force will also increase.
• Angular displacement of the driven wheel
Angular displacement follows the same pattern for all the cases
• Angular velocity of the driver
Angular velocity follows the same pattern.