KNOW WHY WASHER IS USED WITH NUT AND BLOT !!

Washers are often used in conjunction with threaded fasteners. Washers consist of a flattened, circular- or disc-shaped piece of metal with a hole in the middle. Skipping on washers can dramatically reduce the lifespan of how your product is put together. Ultimately, that leads to disaster for the product itself. Not just any washer will do for all applications. Once you understand that, you can give washers the respect they deserve. In this article, we will discuss the use of washers with respect to nut and bolts.

Load Distribution

The primary purpose of most washers is to evenly distribute the load of the threaded fastener with which they are used. Threaded fasteners stress the material in which they are driven. For example, driving a screw into the wood may cause the wood to crack around the surface. Washers reduce the risk of such damage by evenly distributing the fastener’s load across the surface of the material. Not all materials require the use of washers. 

But for wood and other relatively soft materials, washers are useful to protect against stress-related damage when the threaded fastener is driven into the material.

Spacing

Washers can also be used as spacers. If the threaded fastener is longer than the depth of the object, you won’t be able to drive it all the way into the object — not without having some of the fastener stick out the back of the object, at least. Driving a 4-inch screw into an object that’s 3 inches deep will result in 1 inch of the screw’s tip protruding out of the back of the object. 

A simple solution to this problem is to use washers. Placing washers through the threaded fastener before driving it into the object creates padding so that the fastener doesn’t go too deep.

Vibration Absorption

Certain types of washers are designed to absorb vibrations. Known as vibration damping or vibration-isolating washers, they usually aren’t made of metal. Instead, they are made of a softer material like plastic, rubber or urethane. Softer materials such as these are more effective at absorbing vibrations than hard materials, including metal.

If a threaded fastener is being used to connect two objects, and one of those objects producing vibrates aggressively, using vibration-damping washers can protect the other object from damage.

Liquid Protection

Other types of washers prevent the ingress of water and liquids. They are often used in water pipes and connections to create a waterproof seal. Like vibration-damping washers, liquid-sealing washers are made of a soft material that’s able to press completely against the surface of the object.

KNOW THE MECHANISM BEHIND EMERGENCY PULL CHAIN !!

You might have seen an Emergency pull chain in Railways. The chain is used to stop the train at the time of an Emergency. Most of us though know what the Pull chain is been used for but do not know the exact mechanism of it. Here is a brief description of what exactly happens in a Train when you pull the Emergency chain.

In a Typical Indian train, the coaches are interconnected by two pipe hoses. The alarm pull chain is in continuity with the Brake pipe (As in the Schematic diagram below) constantly maintained at specific air pressure.
Whenever the chain is been pulled some Air (earlier vacuum drop was used) escapes from the Passenger Emergency Alarm Valve ( PEAV ) vent. 
 

This drop in pressure results in the application of the brake cylinder/piston assembly in the bogie of the coach, which starts pressing the brake pads on the wheels or disc of the entire train. The loco pilot also notices the air pressure drop in the gauge and then uses his own skills to help the train stop comfortably.

As soon as there is pressure drop, the driver whistles in "two short one long" to indicate to the guard and the train TTEs that there has been Alarm chain pulling.

The guard's compartment also has the air pressure gauge which gives him an indication.

Also recently the coaches have been fitted with emergency flashers on the sidewalls of the coaches, and these flashers are also activated when the brake pipe pressure is lost for any reason other than the driver's application of the brakes.

Assistant Driver and Guard find out in which coach the ACP actually occurred and help to "put right" the concerned coach i.e. the lever needs to be manually reset that helps to release the brakes of that coach. Until this is done, the lamp and buzzer in the locomotive cab are continuously activated. The air pressure system again builds up air pressure and that releases all brakes of all coach and the train gets ready to depart.

KNOW WHY BUCKETS GENERALLY HAVE FRUSTUM SHAPE !!

You might have noticed that buckets generally have a conical or frustum like shape. Have you ever wondered why is it designed so? Why not any other shape?
We will discuss the reason behind the conical shape of the bucket in this article.

The bucket is designed in conical shape due to the following reasons:

1.)A bucket is typically used to put something in, e.g. you dip a mug in it or wash something in it. This means having a large top area is useful for easy access.

2.)It makes it easy to hold or lift the bucket of such shape as any other shape like a cylinder or frustum upside down will have the chances of slipping down.

3.)The center of gravity of frustum shape is such that it provides the least effort and easy means to lift it.

4.)While pouring down the water or liquid out, the frustum of the cone-shaped bucket provides easy grabbing and balance and comfort.

5.)This shape allows multiple buckets to be stacked (nested) inside each other, providing both dense and secure storage of large numbers of buckets.

Compared to the cylinder, a frustum shape gives maximum weight distribution while lifting thus minimum effort is used while lifting bucket of frustum shape.