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MECHANISMS - Coggle Diagram

- - - - Transmit motion and force in a straight line from one point to another
        
        Levers
        
        Rigid bar that is supported by a fulcrum
        
        F is the effort applied at one end of the bar
        
        R is the load that acts at the other end of the bar
        
        d is the distance from F to the fulcrum
        
        r is the distance from R to the fulcrum
        
        Law of the lever: F · d = R · r It indicates a balanced lever
        
        TYPES
        
        Class 1
        
        Class 2
        
        Class 3
        
        Pulleys
        
        TYPES
        
        Fixed pulley
        
        It's balanced when the effort F is equal to the load R
        
        It's a wheel that has a groove around it into which a rope, chain or belt fits
        
        It rotates around an axle that is fixed to an immobile surface
        
        Moveable pulley
        
        It's a set of two pulleys, one is fixed while the other can move in a linear direction
        
        It's balanced when F= R/2. when the force is equal to the load divided by two
        
        Compound pulley
        
        It's a system of fixed and moveable pulleys, often called block and tackle
        
        If we use more pulleys less effort is needed
    - - Transmit motion and effort in a circular way, from the input to the output
        
        Friction drives
        
        Made up of two or more wheels that are in contact
        
        The first wheel is the primary wheel
        
        When it moves it drives the second or output wheel, causing it to move
        
        Each wheel rotates to the opposite direction than the one next to it
        
        The ratio between the rotation velocities of the wheels is expressed by this equation
        
        N1 · D1 = N2 · D2 --> D1/D2 = N2/N1
        
        N are the velocities of the wheels, expressed in revolutions per minute (rpm)
        
        D are the diameters, D1/D2 is called the gear ratio
        
        Pulleys with belt
        
        Two pulleys or wheels that are a certain distance appart
        
        Their axes are parallel and they rotate simoultaneously due to the belt
        
        The rotation of one axlle is transmitted to the other throught the connected pulleys
        
        The 2 pulleys and 2 axles rotate in the same direction
        
        Gear mechanisms
        
        Gear mechanisms and cogwheels
        
        Cogwheels are sets of wheels that have teeths called cogs
        
        They transmit a rotary motion between the two connected axles, which can be parallel, perpendicular or oblique
        
        N1 · Z1 = N2 · Z2
        
        N are the velocities and Z the number of teeth
        
        Z1/Z2 is called the gear ratio
        
        Worm gear
        
        A screw that moves a helical hogwheel that is set perpendicular to the screw
        
        A worm screw fulfills the equation: Nwheel = Nscrew · Zgrooves / Zwheel
        
        Gear mechanisms with a chain
        
        Two cogwheels with parallel axles that are a certain distance appart; they rotate simoultaneously by means of a metal chain or a toothed belt
        
        To calculate the ratio between the velocities of both wheels, use the same formula as for gear mechanisms
        
        Gear train
        
        A system of more than two gears, connected together
        
        Pulley trains with belts
        
        Systems of pulleys, or wheels, with a belt formed by more than two wheels
        
        Variation in velocity
        
        1 more item...
  - - - Rack and pinion system
        
        L=P·Z·N
        
        L is the velocity of the rack's movement, P the distance between consecutive teeth, Z the number of teeth and N the number of rotations/min
        
        uses a small cogwheel, mounted on a toothed belt or bar
      - Nut and bolt system
        
        bolt or threaded bar and a nut that has its same diameter
      - Winch and crank handle
        
        consists of a drum that rotates and a crank handle that allows to pull or lift objects
    - - Crank-link-slider
        
        composed of a crank and a rod called a connecting rod or link
      - Crankshaft
        
        set of connecting rods attached to a jointed axle
        
        it transforms the rotary motion of an axle into a reciprocating motion
      - Cam
        
        a rotating object that pushes a follower as it moves
        
        A set of cams fixed on the same axle is called a camshaft.
        
        it transforms rotary motion into reciprocating motion in the follower
      - Eccentric cam
        
        wheel with an off-centre rotation axle that doesn't coincide with the centre of its circumference
        
        It transforms the rotary motion of the wheel into reciprocating motion in the follower
  - - - Moveable connections are used to connect shafts that can move along the axle or at an angle to each other
    - - 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 rings with balls or rollers between them
  - - - By compression
      - By traction
      - By torsion