Getting Started Tutorials - MechDesigner > Tutorial 5: Kinematic Function Blocks for Motion > Step 5.6: Gearing, Amplitude and Frequency

Amplitude and Frequency

This topic is: How to use the Gearing-Ratio parameter in the Gearing FB to edit the Amplitude and Frequency of motion-values.

Notes:

We use the generic term Crank when the kinematic-element Rocker rotates continuously.

Counter-Clockwise is the positive direction.

This is the most basic application. A crank rotates continuously, and we want it to rotate at a different speed or direction.

We use a Gearing FB to change the angular velocity of a Crank.

Connect a Linear Motion FB to a Gearing FB to a Motion-Dimension FB.

GST-5-504

There are two 'Cranks' in the image.

The right-crank has a Gearing FB.

Left Crank:

Connect a wire from the output-connector from the Linear-Motion FB to the input-connector of the Motion-Dimension FB.

The motion-values from the output of the Linear-Motion FB increases linearly from 0 to 360, and repeats each machine-cycle.

Thus, the Crank rotates Counter-Clockwise* at a constant speed, equal to the MMA.

* Counter-Clockwise is the positive direction of a rotating-Part.

Right Crank:

Connect a wire from the output-connector of the Linear-Motion FB to the input-connector of the Gearing FB.

Connect a wire from the output-connector of the Gearing FB to the input-connector of the Motion-Dimension FB.

Edit the Gearing Ratio parameter.

Gearing Ratio = –1 - the output =360 to 0. The Crank rotates Clockwise each machine-cycle.

Gearing Ratio = +3 - the output is now from 0 to 1080. The crank rotates 3× for each machine-cycle.

We can add a crank to a crank.

GST-5-6-GearingFB-Crank-on-Crank

The image to the left has an Epicycloid Curve. To add an Epicycloid Curve:

1.Join the start-Point of a Part(a) to the Base-Part with a Pin-Joint.

2.Join the start-Point of a Part(B) to the end-Point of the first Part with a Pin-Joint

3.Add Motion-Dimension FBs to Part(a), and then to Part(b).

4.Connect a wire from a Linear-Motion FB to control the motion of Part(a) - it is a Crank.

5.Connect the Linear-Motion FB to a Gearing FB, and a wire to control the motion of Part(B),

6.Edit the Gearing FB, and edit its Gearing Ratio=-3.

7.Add a Trace-Point to trace the path of the end-Point of Part(b)

Note: You can easily replicate this motion with a Gear-Pair. (Orbiting / Epicyclic)

You can use a Gearing FB for different reasons. •Connect a wire from a Gearing FB to the input a Motion FB to change the FREQUENCY of the Motion •Connect a wire from a Motion FB to the input a Gearing FB to change the AMPLITUDE of the Motion •Connect a wire from a Gearing FB to the input a Motion FB and to the input of a Gearing FB to change the FREQUENCY and AMPLITUDE of a Motion You can also use a Gearing FB to change the direction of a motion.
AMPLITUDE:
Change the AMPLITUDE of motion-values	Connect a Motion FB to the input of the Gearing FB. •Linear-Motion FB: output is 0 - 360º •Motion FB output is 0 - 50 - 0mm •Gearing Ratio = 3× - its output is 0 - 150 - 0mm •Base-Value of Motion-Dimension FB = 20mm The Slider moves from 20 to 170 to 20mm in 1 machine-cycle. The Gearing FB increases the AMPLITUDE of the motion.
FREQUENCY:
Change the FREQUENCY of motion-values	Connect a Gearing FB to the input of the Motion FB. •Linear-Motion FB output is 0 – 360º •Gearing Ratio = 3× - its output is 0 to 1080º •Motion FB output is 0 to 50 to 0mm , but 3× in one machine-cycle. The Slider moves 3× in one machine-cycle. The Slider moves from 20 to 70 to 20mm 3× as the MMA in one machine-cycle. The Gearing FB increases the FREQUENCY of the Sliders motion by 3×
AMPLITUDE AND FREQUENCY:
Change the AMPLITUDE and FREQUENCY of motion-values	To change the amplitude and frequency of a motion, connect a Gearing FB before and after a Motion FB.

'Expand' then 'Play'