Please enable JavaScript.

Coggle requires JavaScript to display documents.

MECHANISMS - Coggle Diagram

- - - - They consist of two pulleys or wheels that are a certain distance apart. Their axles are parallel and they rotate simultaneously due to the effect of the belt
    - - The ratio between the rotation velocity of the wheels or pulleys depends on the relative size of the wheels.
    - - Cogwheels are sets of wheels that have teeth called cogs.
      - The ratio between the rotation veloaues of the wheels depends on the number of teeth on each wheel.
    - - This is a screw that moves a helical cogwheel that is set perpendicular to the screw
    - - The gear ratio between the drive wheel (I) and the dnven wheel (4) depends on the number ol geared teeth m the system
    - - The gear rauo between the dnve pulley (I) and the driven pulley l4) depends on the relauve size of the pulleys in the system. It's expressed as a function of their diameters.
        
        Constant system
        
        Reducing system
        
        Multiplying system
    - - The relation between the rotation veloaties of the wheels depends on the number of teeth on each gear.
  - - - This ts a system of fixed and moveable pulleys, often called block and
        tackle.
      - If we use more pulleys, the system becomes more complex, but less effort is needed to move the load.
    - - A moveable pulley is balanced when it satisfies this equation. F=R/2
    - - A fixed pulley is balanced when the effort F is equal to the resistance of the load, R: F = R
      - Pulleys are used to raise and lower loads easily because we use our own weight to counteract them
    - - A lever is a rigid bar that is supported by a fulcrum
      - The following equation modificates a balanced lever.
        F d= f r
      - Types of levers:
        
        Class 2
        
        Class 1
        
        Class 3
  - - - Rack and pinion system
        
        The ratio between the number of rotations of the pinion and the veloaty of the movement of the rack is expressed by this equation: L= P 2 N
      - Winch and crank handle
        
        A crank is a bar attached to an axle that is used to turn it
        
        A winch and crank handle system consists of a drum that rotates and a crank handle that allows to pull or lift obiects
      - Nut and bolt system
        
        This consists of a bolt or threaded bar and a nut that has the same intenor diameter as the diameter of the bolt.
    - - Crank-link-slide
        
        This is composed of a crank and a rod called a connecting rod or link.
        
        Uses: internal combustion engmes, windscreen wipers and machine tools.
      - Crank shaft
        
        This is a set of connecting rods attached to a jointed axle. Each of the joints of the axle acts as a crank.
        
        Uses; combustion engines and sewing machines
      - Cam
        
        This is basically a rotating object that pushes a follower as it moves.
        
        Uses; combustion engines.
      - Eccentric cam
        
        This consists of a wheel with an off-centre rotation axle that doesn't coincide with the centre of its circumference.
  - - - The mechanisms used to
        reduce velocity are called brakes.
        
        Band brakes consist of a metal band that puts pressure on a drum attached to the axle of the oblect we want to slow down.
        
        Drum brakes include one or two brake shoes that come into
        contact with the drum.
        
        Disc brakes consist of pads and a disc attached to the oblect that we want to slow down
    - - Springs are devices that absorb
        energy. This energy can be released
        later, little by little or all at once.
        
        By traction. The sping is stretched, in a bed frame for example.
        
        By torsion. The sping is twisted, in a clothes peg for example
        
        By compression. The sring is compressed, in a chair for example
    - - In bushings the axle or the shaft is
        inserted in a plain circular piece
        that is placed inside a housing to provide
        a bearing surface.
      - Bearings are made up of two
        concentric nngs with balls or rollers
        between them.
    - - Fixed connections are used to
        make permanent connections
        between axles and shafts
      - Clutches are mechanisms that
        allow axles or shafts to be connected
        or separated.
      - Movable connections are used to connect shafts that can move along the axle or at angle to each other.