KNOW WHY KEY IS USED IN TORQUE TRANSMISSION !!

We come across various mechanical components on day to day basis, But we ignore the functionality of various components. We are going to discuss the functionality of one such component. You might have seen shaft and other mechanical components connected with a key. Have you ever imagined why this key is used? Let us explore the reason for the key in this article.

A key is a machine element that is used to connect a shaft to other machine elements like Gears, Pullies, Couplings, Sprockets or Flywheels. The key prevents relative rotation between the two parts and may enable torque transmission.

The key will have a provision in both the shaft and the machine element which needed to be connected. this is called Keyway. These keys are temporary fastening elements and are subject to the crushing and the shearing stress.

Various types of the key are used in power transmission are square key, flat key, Dowel Key and so on.

WHY KEY IS USED IN POWER TRANSMISSION :

Let us assume a situation where the key is not used in power transmission as shown in the figure below. When there is a sudden rise in torque, there might be chances of slip between components.

The key ensures the connection transmits the load, power & rotation without slipping and within the accuracy requirement of the design. Without the key the components may slip and this might result in loss of efficiency.

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KNOW WHERE DOES ELECTRICITY GO AFTER GROUND !

We all know that every electrical equipment is grounded as a safety measure. The ground wire in an electric outlet is a safety valve; any undesired electricity (positively charged energy) flows to the ground and prevents us from shock. But have you ever imagined where this electricity goes from the ground? We will discuss about this in this article.

For clearly understanding this concept consider our household wiring system. To prevent static electrocution the grounding or earthing is done. Also the neutral passes through all household systems and is commonly collected near the transformer and grounded. Thus it returns through the source which produces it. See the below diagram for further explanation.

"Ground" is not where the electricity goes, it's just a term for zero potential. Household power is AC, so charge never really goes anywhere. The same amount of charge is drawn out from the Earth as is put back in. Electricity doesn't work by pumping an extra charge into something. We also know the law of conservation of energy that energy can neither be created nor destroyed. When you connect a circuit to the ground - it completes the circuit back to the source.
So, in short in order to complete the circuit it returns back to the source.
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KNOW WHY THESE HOLES ARE PRESENT IN FLYWHEELS !

We see many mechanical components in day to day life. One such component is a flywheel. We generally see some holes in it. Have you ever imagined the reason for these holes? We will discuss the reason behind these holes in this article.

A flywheel is a mechanical device specifically designed to efficiently store rotational energy (kinetic energy). Since flywheels act as mechanical energy storage devices, their job is also to provide the energy whenever required and that too in a smooth manner. Flywheels resist changes in rotational speed by their moment of inertia. The amount of energy stored in a flywheel is proportional to the square of its rotational speed and its mass.

There are basically two types of holes in flywheel.

Uniform symmetric holes as a part of the design.

These help to reduce the weight of the flywheel. In a flywheel you need a certain moment of inertia. That can be achieved with less weight by having more material near the periphery. So mostly they have a thick outer ring with a thin web and holes in the web.These holes also help while handling the flywheel to put chains an hooks in it.


Small holes drilled on the periphery which will not be symmetrical.

These are holes are drilled at the time of dynamic balancing the flywheel as per need at specific location and diameter and depth. The purpose is to remove the mass. If the flywheel is not balanced, then during high speeds, it will generate unbalanced forces on the shaft on which it is fitted. By removing some portion of the flywheel in the form of these holes, it gets balanced. Also, it helps in materiel saving which eventually reduces the cost.

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