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Mechanisms, imagen_2026-03-20_233423772 - Coggle Diagram

- - - - Rack & Pinion → pinion (cogwheel) rotates, rack moves linearly / L = P × Z × N / reversible / uses: steering, corkscrews, drills
      - Nut & Bolt → bolt or threaded bar + nut / one rotates, the other moves linearly / uses: taps, car jacks, bottle caps
      - Winch & Crank → crank turns drum / longer crank = less effort / F × d = R × r / uses: cranes, roller blinds, coffee grinders
    - - Crank-Link-Slider → crank + connecting rod + slider / rotary motion becomes back-and-forth / reversible / uses: steam engines, combustion engines, windscreen wipers
      - Crankshaft → set of connecting rods on jointed axle / each joint acts as a crank / different rods move at different times / reversible / uses: combustion engines, sewing machines
      - Cam → rotating shape pushes a follower / shape of cam determines type of movement / set of cams = camshaft / uses: combustion engines (valve control)
      - Eccentric Cam → wheel with off-centre axle / distance between centre and axle = eccentricity / uses: sewing machines, windscreen wipers
  - - - Fixed pulley → F = R / changes direction only → uses: wells
      - Moveable pulley → F = R/2 / halves the effort needed
      - Compound pulley (block & tackle) → F = R/2n / more pulleys = less effort → uses: cranes, lifts
    - - Rigid bar + fulcrum (pivot point)
      - Law of lever: F × d = R × r
      - Class 1 → fulcrum between F and R (can multiply or reduce effort) → e.g. scissors, seesaw
      - Class 2 → load between effort and fulcrum (always multiplies effort) → e.g. wheelbarrow
      - Class 3 → effort between fulcrum and load (always reduces effort) → e.g. tweezers, fishing rod
  - - - Two or more wheels in direct contact
      - Output wheel rotates in OPPOSITE direction to drive wheel
      - Gear ratio: N₁ × D₁ = N₂ × D₂
      - Uses: metal sheet production, video players
    - - Two pulleys connected by a belt, axles parallel
      - Both pulleys rotate in the SAME direction
      - Same gear ratio formula as friction drive
      - Uses: car engines, washing machines, drills
    - - Toothed wheels that mesh together
      - Types: spur gear, helical gear (cylindrical) / bevel gear (conical)
      - Two wheels rotate in OPPOSITE directions
      - Gear ratio: N₁ × Z₁ = N₂ × Z₂
      - Uses: automobiles, industrial machinery, domestic appliances
    - - Screw that moves a helical cogwheel set perpendicular to it
      - Each rotation moves the gear forward by the number of grooves
      - Always REDUCES velocity / acts as a braking system
      - Uses: guitar tuning keys, windscreen wipers, gear reduction systems
    - - Two cogwheels connected by a metal chain or neoprene belt
      - Both gears rotate in the SAME direction
      - No slippage between chain and wheel
      - Same gear ratio formula as cogwheels (uses number of teeth)
      - Uses: bicycles, motorbikes, engines
    - - System of 2+ pulleys, pulleys on same axle rotate at same speed
      - Gear ratio: N₄/N₁ = (D₁ × D₃) / (D₂ × D₄)
      - Multiply even-numbered (driven) diameters ÷ odd-numbered (drive) diameters
      - Uses: machine tools, drills, video machines
    - - System of more than two gears connected together
      - Used to multiply or reduce velocity without large diameter gears
      - Gear ratio: N₄/N₁ = (Z₁ × Z₃) / (Z₂ × Z₄)
      - Uses: robotics, gearboxes, kitchen appliances
- - - - Types of movement: linear (straight line), rotary (circular), oscillating (back and forth), and reciprocating (alternating linear).
        
        The main purpose of mechanisms is to transmit force or motion, change speed or direction, or transform one type of movement into another.