Tech Flashcards
What is a pulley?
An example of a simple machine that uses rope around the wheels that have a groove in them
How do you calculate the mechanical advantage of a pulley?
Have to count the number of rope sections that support whatever object you are lifting
The more compound the pulley is….
The easier the load is to lift
Fixed pulley (1 mechanical advantage)
does not change the amount of force applied.
Does change the direction of the force
Moveable force (2 mechanical advantage)
Increases amount of force applied.
Does not change the direction of the force
Block and Tackle (3 mechanical advantage)
Pulley system made up of fixed and moveable pulleys
What is a gear?
Provide a gear reduction in motorized equipment key =
a small motor spinning very fast can provide enough power for a device , but not enough torque
What are Spur gears?
MOST COMMON TYPE OF GEAR
have straight teeth and are mounted on parallel shafts, sometimes many spur gears are used at once to create very large gear reductions
What are Bevel gears?
Useful when the direction of a shaft’s rotation needs to be changed.
TEETH = can be straight , spiral or hypoid
What are Worm gears?
Used when larger gears reductions are needed,
The worm can easily turn the gear, but the gear cant turn the worm
What are Rack & Pinion gears?
Used to convert rotation into linear motion
steering steel on cars
Spur gear ( Advantage )
- Highly reliable
- Simplest , easiest to design & manufacture
- More efficient if you compare it with helical gear of same size
Spur gear ( Disadvantage)
- Slow - speed gears
- Cant transfer power between non-parallel shafts
- Produce a lot of noise when operating at high speeds
Bevel gear ( Advantage )
- Makes it possible to change the operating angle
- Differing the number of teeth on each wheel allows mechanical advantage
Bevel gear ( Disadvantage )
- Must be precisely mount
- Shaft bearings must be capable of supporting significant forces
