Mechanical devices Flashcards
how do circular cams work
use an off-centre pivot to cause the follower to move up and down
where are circular cams used
pistons, steam engines
how do pear cams work
It remains stationary for half a turn then gently rises and falls.
pear cams uses
- used to make carousel horses rise and fall
how do snail or drop cams work
It causes the follower to remain stationary for half a turn before gently rising and suddenly falling. They can only work by rotating in one direction.
snail or drop uses
Used on production lines to make regular holes or cuts in an item as it rotates and drops at regular intervals
what are three types of followers
- flat
- point or knife
- roller
what are gears
wheels with teeth around the outside
what do gears do
change the direction or the speed of movement.
what are gear trains
when two or more gears are joined together
how do gear trains work
the drive gear causes the driven gear to turn in the opposite direction.
which ones the drive gear
the smaller one
which ones the driven gear
big one
how to find gear ratio
number of teeth on driven gear ÷ number of teeth on the drive gear
what are pulleys
use mechanical advantage, similar to levers, to lift up loads
