IB Design Technology Topic A3.3: Introduction to Mechanical Systems Key Definitions

A lever where the fulcrum is between the effort and the load. For example, a seesaw or a pair of scissors.

A lever where the load is between the effort and the fulcrum. For example, a wheelbarrow.

A lever where the effort is between the fulcrum and the load. For example, tweezers and most human limbs (like your forearm) are 3rd-class levers.

A linkage that converts vertical motion into horizontal motion, or the other way around.

A belt transfers power between at least two pulleys — the driver pulley moves the belt, and the driven pulley is moved by it.

A pair of toothed rotating gears that transfer power between intersecting shafts, usually at a 90° angle.

A mechanical part that converts rotational motion into linear motion.

A system combining fixed and movable pulleys to reduce effort and increase mechanical advantage, making it easier to lift heavy loads.

A pulley that is attached to a fixed support and changes the direction of force without altering the mechanical advantage.

A toothed wheel that meshes with another to transmit motion or change speed/direction.

Spreads force over a longer distance, making it easier to lift or move objects.

A rigid bar that pivots on a fulcrum to move a load with an applied effort.

Movement in a straight line, in one direction or back and forth.

A mechanical system of connected parts that changes the direction or size of a force.

The ratio of output force to input force in a mechanical system.

A set of physical components that convert input force and motion into a desired output.

A pulley that is attached to the load, allowing it to reduce the effort needed by increasing mechanical advantage.

Movement back and forth along a curved path.

A linkage system where a central point is constrained to move in a nearly straight line.

A mechanism where a central point is constrained to move in a nearly straight line by the arrangement of linked bars.

A grooved wheel that uses a rope, cord, chain, or cable to transmit energy and motion.

A linkage system that allows force to be transferred in both directions — when pushed or pulled.

A mechanical system where a toothed bar (rack) engages with a circular gear (pinion) to convert rotary motion into linear motion.

A mechanical device that allows motion in one direction only. The pawl fits into the teeth of the ratchet wheel, preventing backward rotation while allowing forward movement.