tecnología / technology

máquinas / machines -->


Machine (máquina)

Any mechanical or electrical device that transmits or modifies energy to performe some activity.

    It make our work easier by
  1. transferring a force from one place to another (a more convenient point),
  2. changing the direction (convert a rotary motion into a linear motion, up into down) of a force,
  3. increasing the magnitude of a force (lift weight much greater than one could do unaided),
  4. increasing the distance or speed (slow motion into a more rapid motion) of a force.
In a simple machine (máquina simple) a force is applied to the device at one point, and it does work moving a load, at another point. Although some machines only change the direction of the force.

The mechanical advantage (ventaja mecánica) is the number of times a machine multiplies your effort force.
The actual mechanical advantage of a machine is always less than the theoretical value.
The efficiency (rendimiento o eficiencia) is the ratio between the amount of energy produced and the amount of energy expended and it is always less than 100 per cent.

A Compound or complex machine (máquina compuesta)
It is two or more simple machines working together to make work easier.

A device that changes electricity or fuel into movement and makes a machine work.

A machine that uses the energy from liquid fuel or steam to produce movement.

Input force: Applied Force, Effort or Power
Output force: Weight, Load or Resistance
Mechanical Advantage = Resistance force / Power force
Efficiency = Output energy / Input energy x 100
Work = Force · Distance
Torque (moment of a force) = Force x Distance.

Mechanism (mecanismo)
A part of a machine, or a set of parts that work together.
Mechanisms are used to convert between one type of motion and another.

    Mechanisms can be classified by function:
  • Transmission of motion
    • Linear transmission
      • Lever
      • Pulley
      • Block and tackle
    • Rotary transmission
      • Friction wheels
      • Pulleys-belts
      • Gears
      • Sprockets-chains
      • Gear trains
      • Pulley trains
      • Worm-gear
  • Transformation of motion
      • Rotary-linear
      • Wheel
      • Rack-pinion
      • Nut-bolt
      • Winch-Crank
      • Reciprocating rotary-linear
      • Crank and rod
      • Crankshaft
      • Eccentric camCam
      • Camshaft
  • Motion control
      • Direction control
      • Ratchet
      • Freewheel
      • Speed reduction
      • Brake
  • Energy accumulation / dissipation
      • Absorption or accumulation
      • Spring
      • Dissipation
      • Shock absorbers
      • Leaf springs
  • Making connection
      • Linkage
      • Rigid couplings
      • Clutch
      • Flexible couplings
      • Support
      • Plain bearing
      • Antifriction bearings
  • Transmission, control and support
      • Freewheel

  • Lever (palanca)
    A lever is a bar that is free to turn about a fixed point.
    The mechanical advantage is the ratio of the resistance(load) arm to the power(effort) arm.

    Wheel and Axle (rueda y eje)

    A wheel and axle has a larger wheel (or wheels) connected by a smaller
    cylinder (axle) and is fastened to the wheel so that they turn together.
    The increased distance over which the force is applied as the wheel turns results in a more powerful force on the axle, which moves a shorter distance.
    The mechanical advantage is the ratio of the radius of the wheel to the radius of the axle.
    Examples: Door Knob, Wagon, Toy Car, Steering wheel, Screwdriver, Faucet (tap) handle and wrench (spanner), Bicycle handlebars, Hand crank.

    Friction wheel(ruedas de fricción) or Friction drive

    pulley and belt (polea y correa) or Belt drive

    Pulley (polea)
    A wheel that usually has a groove around the outside edge. This groove is for a rope or belt to move around the pulley.

    Inclined plane (plano inclinado)

    A sloping surface, such as a ramp. The mechanical advantage of an inclined plane is equal to the length of the slope divided by the height.
    Examples: Staircase, Ramp, Bottom of a Bath Tub

    Wedge (cuña)

    It is used to split things. It can either be composed of one or two inclined planes. The mechanical advantage of a wedge can be found by dividing the length of the slope by the thickness of the big end.
    There are two major differences between inclined planes and wedges. First, in use, an inclined plane remains stationary while the wedge moves. Second, the effort force is applied parallel to the slope of an inclined plane, while the effort force is applied to the vertical edge (height) of the wedge.
    Examples: The cutting edge of scissors, Axe, chisel, Zipper, Knife.

    Bolt or Screw (tornillo)

    An inclined plane wrapped around a shaft or cylinder. It is a central core with a thread or groove wrapped around it to form a helix. While turning, a screw converts a rotary motion into a forward or backward motion, the distance moved is equal to the distance between two connective threads. This distance is called the pith.
    It is used to hold things together. it may be used to raise weights or overcome resistance applied to its ends.
    Archimedes Screw . An ancient device for lifting water. It consists of a spiral tube wrapped around an inclined rod. As long as the rod is turned, water enters through the open bottom end of the spiral and is slowly raised to the top where it pours out.
    Examples: Bolt and nut, Spiral Staircase, screw press, screw jack.

    Winch or Windlass (torno o cabrestante)

    A machine which lifts or move heavy objects by turning a chain, cable, rope, belt or crank around a tube-shaped device (cylinder or barrel).
    A windlass is an apparatus for moving a heavy weight. Typically, a windlass consists of a cylinder (barrel), which is rotated by the turn of a crank or belt. A winch is affixed to one or both ends, and a cable or rope is wound around the winch, pulling a weight attached to the opposite

    Gears (engranajes)
    It is really just a wheel with teeth. Two toothed wheels (driver and driven or follower) fit together either directly or through a chain or belt so one wheel will turn the other. Some gears may have a screw or a toothed shaft in place of one of the wheels. A gear may also be a combination of toothed wheels that produces a certain speed .
    The gear ratio es the relationship between the number of teeth on two gears that are meshed or two sprockets conneted with a common roller chain or the circumferences of two pulleys connected with a drive belt.
    In any pair of gears the larger one will rotate more slowly than the smaller one, but with greater rotation force (torque).
    Examples: Clock, Automobile, Drill, bicycles, eggbeaters.

    Eccentric wheel or eccentric cam (rueda excéntrica)

    It is a disc with its centre of rotation positioned ‘off centre’. This means as the cam rotates the flat follower rises and falls at a constant rate.
    Crank and Connecting Rod (biela-manivela)

    Crankshaft (cigüeñal)
    Cam (leva)

    A rotating disk shaped to convert circular (rotary motion) into reciprocating motion of the follower.
    Ratchet (trinquete)
    A ratchet is a device that allows a wheel to turn in only one direction. A bar on a pivot called the "pawl" is fixed above the ratchet wheel. The pawl slides over the teeth of the ratchet in one direction, but blocks the motion of the teeth if the wheel turns in the other direction.
    Springs (muelles)
    Springs perform different actions.
    Main types of spring:
    Spring resisting stretching (extension spring). spring resisting compression (compression spring). spring that resists twisting (torsion spring).
    clutch (embrague)
    A coupling that connects or disconnects driving and driven parts of a driving mechanism.
    A pedal or lever that engages or disengages a rotating shaft and a driving mechanism.
    brake (freno)
    A restraint used to slow or stop a vehicle.
    Universal joint, U joint, Cardan joint (junta universal o Cardán)
    It is a rigid rod that allows the rod to 'bend' in any direction, and is commonly used in shafts that transmit rotary motion. It consists of a pair of hinges located close together, oriented at 90° to each other, connected by a cross shaft.
    shock absorber, shock, damper or dashpot (amortiguadores)
    It is a mechanical device (one kind of dashpot) designed to smooth out or damp shock impulse, and dissipate kinetic energy.

    Heat engines (máquinas térmicas)

    Direct heat engine: They receive heat and convert part of it ot work.

    External combustion engine (máquina de combustión externa)
    The fuel was burnt outside of the engine in a boiler, to produce steam, which powered the engine.

    Internal combustion engine (máquina de combustión interna)
    The engine being powered by the expansion of hot gases produced by the burning of fuel

    Reversed heat engine: They receive work and convert part of it to heat. Examples: refrigerator (fridge) and heat pump.