The mechanical systems They are a set of components, elements or physical devices whose specific function is to convert or transmit the movement and the input force generated by some source of energy, to the movement and the output force that it is desired to produce. Therefore, they are systems that have moving parts.
That is, any system that has several moving parts that move in such a way that together they produce mechanical or other advantages can be considered as a mechanical system..
For example, when a blind is opened or closed with a crank, the point of a pencil is removed with a pencil sharpener, or a vehicle is driven, mechanical systems are being used to help perform those actions..
The automobile used daily has four wheels with circular motion. The engine inside has a piston moving up and down. The cam goes round and round. The car itself moves. The whole system has a lot of things in motion to gain mechanical advantage.
The energy could come from electricity, gasoline, or solar energy, but the energy often comes from humans. Structures like pyramids were built solely with human energy.
For example, the energy required to move a bicycle comes from a human being pedaling.
The driving elements and the transferred movements can be three different types of movement:
They are the mechanisms where the input element and the output element have the same kind of movement.
For example, the mechanism of the bicycle, because its driving element (pedals) has a circular movement and the output system (rear wheel) also has a circular movement.
They are the mechanisms where the input element and the output element have different kinds of movement.
For example, the mechanism that raises a blind using a crank, because its driving element (crank) has a circular movement, and the output system (blind) has a linear movement.
It refers to the ratio of the speed of rotation existing between the output shaft with respect to that of the input shaft of the mechanical system. It is an essential value, because it indicates how the speed of movement is modified in the mechanical system:
- Transmission ratio = output speed / input speed.
If the ratio is less than 1, it means that the mechanism slows down, being a reduction mechanism. If it is greater than 1, then the mechanism increases the speed, being a multiplier mechanism.
Finally, if it is equal to 1, then the mechanism does not decrease or increase the speed, if not only transmits the movement, being an equalizing mechanism.
Mechanical systems and mechanisms are made up of at least the following three large blocks of elements:
The part corresponding to the input of the system is any type of movement and force that serves to start the movement of the mechanical system.
The motion and driving force input can come from any source of energy, such as human effort, energy from wind, water, heat, etc. It can also come from a chemical reaction or from an electrical, mechanical, pneumatic or hydraulic device.
The part corresponding to the transmitter block of the system is where the mechanisms that serve to convert the movement and the input force into a movement and the output force are used..
In other words, it collects, transfers and alters the forces and movement supplied to it by the devices of the engine block, leading them to the output system..
Output refers to the change produced by the transmitter block in the applied movement and input force.
Therefore, this system is the set of elements that receive the forces and movement of the mechanism as such, performing the work for which the mechanical system was conceived at the output..
The input or driving element of the bicycle are the pedals, which, thanks to the cyclist's legs, receive a driving force. The output or receiver element is the rear wheel, because it is the one that finally receives the movement.
Its transmitter block is a system of chains and sprockets, which allows transferring the driving force supplied by the cyclist with the pedals to the rear wheel.
This system shows a quite important advantage in relation to other systems that serve to convert the rotary movement into longitudinal.
This is because for each turn made of the screw, the nut only advances the distance between the threads or thread pitch, which is why the longitudinal or tightening force is very large..
The system is made up of two shafts (input and output), two pulleys (input and output) and a belt.
It is used to transmit a rotary movement from one axis to another, being able to change its direction and speed characteristics. For example, the transmission of a lawn mower using wedge belts and pulleys
It is used to transmit force from one module to another within a team. It is made up of two toothed wheels, the largest being called the crown and the smallest pinion. Transmits a rotating movement through the contact of the sprockets.
A very important application is to transmit the movement from the axis of an energy source, such as an internal combustion engine or an electric motor, to an axis located at a certain distance, which is the one that must carry out the work..
It is made up of a rotating element, called a crank, connected to a rigid bar, called a connecting rod, in such a way that when the crank rotates, the connecting rod is forced to move back and forth alternately. Thus, this system transforms the rotary movement into an alternating longitudinal movement..
The system is reversible, because it can also work to convert an alternating rectilinear movement into a rotary one, as happens in a car engine with a piston inside the cylinder, where the crank is forced to rotate.
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