﻿ Step 5.6: Gearing, Amplitude and Frequency

# Step 5.6: Gearing, Amplitude and Frequency

### Amplitude and Frequency

This section explores the Gearing FB. The Gearing FB dialog-box has parameters to specify similar functionality to a 'Belt and Pulley'.

The Gearing FB applies a basic mathematical function to transform input values at the input-connector to output values at the output-connector.

There are three Parameters in the Gearing dialog-box.

#### The Crank at a speed that is different to the MMA

+

+

To drive a 'crank' at other speeds, or even backwards (clockwise), connect a Gearing FB, between the Linear-Motion FB and the Motion-Dimension FB.

 There are two 'Cranks' in the image to the left.   Left-side Crank: Its motion is given by the motion-values at the output-connector of the Linear-Motion FB. This increases linearly from 0 to 360, and repeats. Thus the Crank will rotate Counter-Clockwise.   Right-side Crank: Its motion is determined by the Linear-Motion AND Gearing FB . Edit the Gearing Ratio in the Gearing FB dialog-box  to -1.  The output will be -360 to 0 and repeat. Thus the Crank will rotate Clockwise.

#### Cranks on Cranks –

+

We can add a crank to a crank.

Shown here is an Epicycloid Curve called the '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 with a Linear-Motion FB – it is a 'Crank'.
 4 Make the second Part half the length of the first Part
 5 Drive the second Part, with a Gearing FB, and edit its Gearing Ratio to '-3'.
 6 Use a Trace-Point 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.

#### Use the Gearing FB to change a Motion's Amplitude AND Frequency

There are three ways to use Gearing Function-Blocks:

 • To amplify (or attenuate) the magnitude of a motion
 • To increase (or reduce) the frequency of a motion
 • To change the magnitude and frequency of a motion

AMPLITUDE:

Here, we connect a Motion FB to the Gearing FB.

For example:

 • Linear-Motion FB range = 0–360º
 • Motion FB range = 0–100mm
 • Gearing Ratio = '3'...

...the slider motion = 'Base-Value + 300mm'

The Gearing FB increases the AMPLITUDE of the Slider.

FREQUENCY:

Here, we connect the Gearing FB to 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 = 0–100mm every input of 360.

Thus, slider completes its motion 3 times in one cycle of the Master-Machine-Angle.

Note - if the Gearing FB is '–ve', the input to the Motion FB is 360 to 0, thus the Motion becomes reversed.

AMPLITUDE AND FREQUENCY:

To change the amplitude and frequency of a motion, connect a Gearing FB before and after a Motion FB.

Help Files for MechDesigner and MotionDesigner 11.1 + © Machine, Mechanism, Motion and Cam Design Software by PSMotion Ltd