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Mechanism, Mechanisms that transform motion, WHAT IS MECHANISM, A fixed…
Mechanism
Pulley trains with belts
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Pulleys 2 and 3, attached to the same axle, rotate at the same velocity
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The motion of pulley 3 is transmitted to pullev 4 via the belt that connects them All the pulleys rotate in the same direction
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Linear motion mechanisms
Levers
A lever is a rigid bar that is used with a point of support or a fulcrum. The mechanical force or effort is applied on one end of the fulcrum. The mechanical force or effort is applied on one end of the acts on the other end of the lever
Types of levers
There are three types of levers — class l, class 2 and class 3
They' re classified accordmg to the position of the load and
effort.apphed in relation to the fulcrum
Fixed pulleys
A fixed pulley is a wheel that has a grove for a rope, cham or belt to go round lt. It rotates around an axle that ls fixed to an immobile surface. This reduces the load. R when elfort, f, is applied
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Compound pulleys
This is a set of fixed and moveable pulleys, often called a block and tackle. If we use more pulleys it becomes more complex, but less effort is needed to move the load
Uses: ln passenger hfts, goods lifts, cranes
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Worm gear
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Each time the screw rotates the gear moves forrward as many teeth as grooves in the screw (normally a small number, I, 2 or 3)
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We' re surrounded by obiects that move or have the capacity to move. We' re surrounded by obiects that move or have the capacity to move
The sistern of gears with a chain for bicycles, the cogwheels of a clock, the lever of a seesaw, the pulley used to get water from a well are some of the simplest mechanisms that are part of many mechanical obiects.
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Rotary motion mechanisms
Friction drives
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Wheel ( 1 ) Is called the primary
drive wheel When it moves, it turns or drives the output wheel (2), causing it to move as well.
The output wheel rotates in the opposite direction to the primary
wheel. If we use more than two wheels, each one rotates in the opposite direction to the next to it
Gear train
This is a system of more than two gears, connected together as shown in the diagram
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When there are two wheels, each connected geared wheel rotates in the opposite direction to its partner.
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The most important element in all of them is the motor or driving force that starts the movement This motor can be a spring, an electric motor or our own muscles The movement or motion produced by the motor can be transformed and is transmitted via different mechanisms to the output elements lwheels, hands, mechanical arms)
so that the objects do the job for which they were constructed.
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WHAT IS MECHANISM
Mechanisms are devices that transmit and convert forces and motions from a driving force (input) to an output element. They enable us to carry out certain tasks with greater comfort and less effor
A fixed pulley is balanced when the effort, F, is equal to
the load. R:
F = R
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These transmit motion and force in a straight line from one point to another, for example, a lever or a pulley (fixed, mobile and compound pulleys)
These transmit motion and effort in a circular way from the input to output. Rotary motion mechamsms include friction drives, pulley systems, gears and worm gears
The ratio between the rotation velocities of the wheels or pulleys depends on the relative size of the wheels. It is expressed by this equation.
The links in the chain or the teeth in the belt have to be the same size and shape as the gear teeth
Imagine you' re pedalling a mountain bike.