MY KNOWLEDGE ABOUT MECHANISMS

We have been working on mechanisms and simple machines since we started in September. Now, is time to show my knowledge about them. Let's begin!


SIMPLE MACHINES

What is a simple machine? A simple machine is an object that make it easier for people to do work, due that we don't have to use as much force. There are 6 types:

INCLINED PLANE:  Is a ramp that helps moving objects up and down heights, because the force needed is reduced as the distance covered is longer. A good example of an inclined plane used in our daily life are stairs.

LEVER: It let us to lift loads with less effort. It is composed by a long rigid body and a fulcrum. The order of the elements (effort, fulcrum, and load) can vary. So, we have 3 different types.

In the first type the fulcrum is located in the middle; In the second type the load is between the two other elements; and in the last type, the effort is the central element:

SCREW: With this simple machine, we get linear motion from rotational motion. It simply is a thin piece of metal shaft (usually with spiral threads that cover all its lenght), that is united to a turning head with a furrow, located on the top and used to turn de screw. The strength increases as the threads are wider and located closer.

We use screws in our daily life, for example, a light bulb has a screw integrated. 

PULLEY: Sometimes, it is not enought with human force to lift heavy objects. To solve this problem, we use the pulley. It is a simple machine, and the basic ones consist of 4 parts:

The axle, the groove. a wheel and a rope. The wheel turns on the axel, and it has a groove along its circumference where the rope is placed. There is an option of put two or more pulleys to create a lifting machine.

An example, can be a flower basket. Compare the two images:

WHEEL AND AXLE: Perfect to move extremelly heavy objects.In this machine, a wheel is locked on a central axle, and they rotate when a force is applied on either one of them. This is because it reduces the friction. A very clear example is a wheelchair, used to carry persons that can't move.

WEDGE: A wedge is just two inclined planes placed backwards with the finnality to get a sharped edge. But, unlike them, it is unfixed; this means wedges need movement for be useful. It has so many uses, but one of them is for cutting objects (eg: saw).

TRANSMITION OF MOVEMENT:

What is the transmition of movement? Mechanisms have 4 basic types of motion, that are the following ones:

• ROTARY MOTION:Is a circular movement, such as a wheel turning.
• LINEAR MOTION: is moving one way in a straight line, such as on a paper trimmer.
• RECIPROCATING MOTION: is moving backwards and forwards in a straight line, as in cutting with a saw.
• OSCILLATING MOTION:Is moving backwards and forwards in an arc, like a pendulum in a clock.

MECHANISMS:

What are mechanisms?: Simple objects that change input motion into output motion, used, as well as simple machines, to simplify work. There are differents types, but in this post I will explain the 3 most used ones:

GEARS: Gears are toothed wheels used for increase or decrease the speed or the force of a machine, or also changhe its directional motion. There are different types:

• GEAR TRAINS: Group of 2 wheels at list that are linked togheter. It has one gear that it is called driver, that turns the other gears, named driven gears.

• RACK AND PINION: It turns rotary motion into linear motion. A round gear (pinion) is turned to move a flat gear (rack).
  
• BEVEL GEARS: It changes the direction of motion throught 90º.
  

CAMS: Cams are mechanisms that consist of a cam or an eccentric and a follower. Sometimes, it includes a wheel to reduce friction.

They work by turning a handle, or a motor. It turns the cam or eccentric, and depending of its shape, the follower will go up and down in a determinated time. These are some examples: 

• Circular cam
  
• Pear cam 
  
• Four-lobed cam
• Snail Cam
  

• PULLEYS: Pulleys are used to change various factors, like the speed, turning force, and the direction of rotation. It has two smooth wheels connected by a belt.

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PERSONAL INTERESTS:

I can't live without music. Did you know that a music tower contain gears inside? Me neither!

Also, I'm very impatient. I'm always asking what time is it, so a watch is necessary in my life. Nowadays, the most of the watches are digital, but, the firsts ones had a gear system in their inside.

LAST BUT NOT LEAST: There is a very short mind map about the unit:

https://mm.tt/791131428?t=Ws0SfRcdZ3

THANK YOU FOR READING!

MARIA NADAL.