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

# 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.

We will use the Gearing-Ratio parameter. The motion-values in this tutorial are given to a rotating part we call a Rocker or Crank.

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

#### Crank speed: Rotate a Crank at a speed that is different to the MMA

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 --- ---  There are two 'Cranks' in the image. The right-crank has a Gearing FB. Left Crank: The Linear-Motion FB increases linearly from 0 to 360, and repeats. Thus, the Crank rotates Counter-Clockwise at a constant speed, equal to the MMA. Note: Counter-Clockwise is the standard positive direction. Right Crank: Edit the Gearing FB to edit the Gearing Ratio parameter. Gearing Ratio: = -1 : The output = 0 to –360. The Crank rotates Clockwise each machine-cycle.   Gearing Ratio: = 3 - the output is now 0 to 1080. The crank rotates 3x for each machine-cycle.

#### Crank on Crank + + We can add a crank to a crank. Shown to the left is an Epicycloid Curve called a Deltoid – it has a shape like a delta. To do this: 1.Connect two Parts end-to-end with Pin-Joints, the first Part to the Base-Part 2.Use Motion-Dimension FBs fix the initial angle of the two Parts.3.Drive the 'first' Part joined to the Base-Part with a Linear-Motion FB – it is a 'Crank'.4.Make the second Part half the length of the first Part5.Drive the second Part, with a Gearing FB, and edit its Gearing Ratio to '-3'.6.Use a Trace-Point to trace the path of the Point at the end of the 'second' Part to show the Deltoid - the deltoid curve is the trace of the point at end of the second Part.Note: You can easily replicate this motion with a Gear-Pair.

#### Gearing FB : Motion Amplitude AND Frequency

 There are three ways to use a Gearing FB. We can connect Gearing FBs 'before' and 'after' a Motion FB. A Gearing FB x •before a Motion FB will change the frequency of the Motion•after a Motion FB will change the amplitude of the Motion•before and after will change the magnitude and frequency of a motion.Also, we can use a Gearing FB to change the direction of a motion. AMPLITUDE: Here, we connect a Motion FB to the input of the Gearing FB. For example: •Linear-Motion FB range = 0 to 360º•Motion FB range = 0 to 90mm •Gearing Ratio = '3'...The Gearing FB changes the AMPLITUDE of the Slider 0 to 270mm FREQUENCY: Here, we connect the Gearing FB to the input of the Motion FB. For example: •Linear-Motion FB range = 0 – 360º•Gearing Ratio = '3', •Input to Motion FB: range 0 – 1080º•Output from Motion FB range = 0 – 90mm 3 times in one machine-cycle.The Gearing FB increases the FREQUENCY of the Sliders motion by 3x Note - if the Gearing FB is '–ve', the input to the Motion FB is 0 to -360 thus the Motion is 'played' in reverse. AMPLITUDE AND FREQUENCY: To change the amplitude and frequency of a motion, connect a Gearing FB before and after a Motion FB. VIDEOS :