mechanical devices Flashcards
motion in a straight line:
linear
motion in a circular motion
rotary
backwards and forwards motion:
reciprocating
a swinging motion backwards and forwards
oscilating motion
what is a mechanism?
device that changes an input into an output motion
what is a lever?
a mechanism which creates movement around a fixed point and makes lifting something easier
what are the three types of levers?
-reverse motion linkage
-parrallel motion linkage
-bell crank linkage
what is mechanical advantage?
where the force that comes out is more than the force that is put in.
what are the two parts of a lever?
a fulcrum and a bar
what are the three factors to consider when using a lever?
The effort: the force that is input.
The load: the force that is output.
Position of the fulcrum (pivot).
first order lever
Elephant
Fanny
Laughed
second order lever
Elephant
Larry
Farted
third order lever:
Fredrick
Elephant
Laughed
what can the first order lever be used for?
crow bar
What can the second order lever be used for?
wheelbarrow
what can the third order lever be used for?
tweesers
what do cams and followers do?
change a rotary motion into a reciprocating motion
what are the 4 types of cams?
-eccentric cam
-pear cam
-snail cam
-heart-shaped cam
what are the 3 different types of followers?
-knife edged
-flat follower
-roller follower
what are the properties of knife edged followers?
Good for precision.
Not good for heavy loads.
Low friction - however tip wears easily.
what are the properties of flat followers?
Not good for precision.
Good for heavy loads.
Large flat surface creates friction.
what are the properties of a roller follower?
Some precision.
Good for heavy loads.
Roller rotates reducing friction.
what are gears?
wheels which interlock to move the force. different sized gears increase and decrease the speed they turn
what is a pulley system used for?
used to change the speed, direction and/or power of the output motion.
what can a simple pulley system be used for?
to lift heavy loads
