DTOTW - Mechansims for use in mechanical toys and automata. Velocity ratios and levers introduced as a background to the theory behind simple mechanisms. Mechanical toys and Automata project - Guidance, Help and Research starting points - Resources fro students and teachers of Design & Technology at KS3, KS4 and KS5 - and beyond. Gear ratios - Velocity ratios - Driven velocity - Input speed - Output Speed - Simple Gearing example
Revision
Year 9 ~ Thinking about projects ....
23 - DTOTW - Innovation and Invention.  Plastics and metal tubes have influenced the designs of furniture as well as many other simpler products.  Ball pens Bics -  Biros & even crazy inventions  depend on the development of materials and processes of manufacture. 3Ms - Design & technology On The Web - Help pages for students and teachers of D&T - Mr Richmond Help
21 - GCSE and Basic coverage for Textiles and the various origins of the different classifications.  Cellulose, synthetics, silk, wool, flax and cotton.  Microscope views of various fibres. Downlaodable historic information on cotton, wool and flax weaving. - DTOTW - Design & Technology IWB resources and links for students and teachers of D&T.
23 - DTOTW - Innovation and Invention.  Plastics and metal tubes have influenced the designs of furniture as well as many other simpler products.  Ball pens Bics -  Biros & even crazy inventions  depend on the development of materials and processes of manufacture. 3Ms - Design & technology On The Web - Help pages for students and teachers of D&T - Mr Richmond Help
21 - GCSE and Basic coverage for Textiles and the various origins of the different classifications.  Cellulose, synthetics, silk, wool, flax and cotton.  Microscope views of various fibres. Downlaodable historic information on cotton, wool and flax weaving. - DTOTW - Design & Technology IWB resources and links for students and teachers of D&T.
~ CAMS ~ Making things move ‘up and down’
                                 or from ‘side to side’.
Look around at the links, levers, cams, pulleys and gears that are used in everyday situations and try to think of new ideas for mechanical toys.  Look at the web-sites that show ‘automata’ and analyse why these toys work as they do.
Start by looking at the three ‘orders’ of levers.  The first class ~  Number 1 is a simple see-saw or scissors.  Notice how the effort needed to move the load is reversed in the direction it acts on the load.  Look at the other two classes and see if the same happens with those. Class 2 is seen in the example of the wheelbarrow and the class 3 lever is seen in things such as tweezers and fishing rods. This last class is an inefficient system as the load is further from the fulcrum than the effort.
              Class 1                                Class   2                                 Class 3
The two illustrations shown here demonstrate how  two dimensional movement can be produced from either a simple circular cam that has an offset central
axle, or from a more complex pear shaped cam (See the ‘cats’ model above).  Still more complex movements  can be produced from a wavy line cut into a cylinder (see the dog’s head shown above)  or from a specially shaped cam.
        
With odd shaped CAMS a prototype should be
made from  card and the output movement
 gradually improved until the  required
result is achieved. They can be linked with
                               levers to give more     
                              effects as in the
                               animation above.
Must revolve one way only
~ GEARS ~  Can be used for Changing the speed of things  ~   
     ....   or for Reversing the direction of motion  - or changing the plane of                                                         movement    ( i.e move the plane through 90
The most important feature of understanding gears in KS3 and KS4 projects is to be able to predict how fast an output gear wheel is going to be turning from a particular input gear speed.           
Each time one tooth of a gear wheel moves it passes on the same movement to the interlocking gear. You would therefore expect two gear wheels each with 100 teeth to rotate at exactly the same speed.....wouldn’t you.  If one wheel had twice the number of teeth that the input gear had  then you might expect
it to take longer to turn round     -    and if it had fewer teeth ... ?
This is called the VELOCITY RATIO.  It is the relationship of how fast the input gear goes round compared to the output wheel.  Ask for help  if you are not sure how to work this out. First find the Gear Ratio (GR) … Then simply think of the ’speed’ at which this will make things turn round...    
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