• Essential Questions

    1.     Which mechanism would be used to increase speed?

    2.     Which mechanism would be used to increase torque or force?

    3.     How do you change types of motion using mechanisms?

    4.     Where are mechanisms used in real-life applications and what is their purpose?


    Key Terms

    Belt and pulley

    The transmission of power between shafts by means of a belt connecting pulleys on the shafts.

    Bevel gear

    One of a pair of gears used to connect two shafts whose axes intersect.


    A connected flexible series of links used for fastening or securing objects and pulling or supporting loads.

    Crank and slider

    A pivot pin near the outside edge of a wheel or disk that changes rotary motion into reciprocating motion.

    Drive gear

    The gear which transmits power and motion to the rest of the system. The input gear.

    Driven gear

    The member of a pair of gears to which motion and power are transmitted by the other. The output gear.


    The ability to do work.


    A push or pull on an object.


    A toothed wheel that works with others to alter the relation between the speed of an engine and the speed of the driven parts.

    Gear ratio

    The ratio of the speed of the driving member of a gear train to that of the driven member.

    Idler gear

    A gear between the driver and the driven gear used to change rotational direction.


    Something put into a system, such as resources, in order to achieve a result.


    Opposite in position, direction, order, or effect.

    Linear motion

    Movement in a straight line.


    The part of a machine which contains two or more pieces arranged so that the motion of one compels the motion of the others.


    A swing back and forth at a regular rate.


    The results of the operation of any system.


    The distance between adjacent threads in a screw.

    Rack and pinion

    A rotating gear that meshes with a bar that has gear teeth along its length. Changes rotating motion into linear motion.


    The quantitative relation between two amounts showing the number of times one value contains or is contained within the other.


    A back and forth movement.

    Rotary motion

    Circular movement.

    Simple gear train

    A combination of two or more gears used to transmit motion between two rotating shafts or between a shaft and a slide.


    Toothlike projections arranged on a wheel rim to engage the links of a chain.


    A twisting force.


    The application of force that moves an object a certain distance.

    Worm and wheel

    A mechanical arrangement consisting of a toothed wheel driven by a short revolving cylinder bearing a screw thread.