KNOW WHY CONSTRUCTION MACHINES ARE PAINTED YELLOW IN COLOUR !!

You might have noticed that most of the construction machines are yellow in colour. We will discuss the reason for this in this article.

Warning signs are frequently yellow, yellow/black striped, or red. And additional to that, yellow is quite a bright and noticeable colour that doesn't usually appear elsewhere in our modern world, so is immediately easily noticed. So, in short yellow is the colour that gets noticed by everyone easily.

On the construction site, man and machine are working side-by-side and close together. For this reason, every construction machine must be as salient and noticeable as possible in order to be visible and to avoid accidents.

Therefore, excavators, cranes, coaters and therelike are painted in the most conspicuous colors, such as yellow, red, orange or another warning color, so that they stand out from the dust, the ground and the other colors on a construction area or roadworks. After all, it would be fatal if a construction worker could not see a construction machine coming.

However, the exact color depends on several factors. First of all, the color of the construction machines often depends on the respective company or the manufacturer of the equipment. For example, some companies are painting their machines as a recognition symbol rather yellow, others red. Partially, however, the colors are also regulated by law.

KNOW WHY FIRING ORDER IS 1-4-3-2 , RATHER THAN 1-2-3-4 !!

Every engine cylinder must fire once in every cycle. This requires that for a four-stroke four cylinder engine the ignition system must fire for every 180 degrees of crank rotation. For a six cylinder engine the time available is only 120 degrees of crank rotation. The order in which various cylinders of a multi cylinder engine fire is called the firing order. The number of possibilities of firing order depends upon the number of cylinders and throws of the crankshaft.

Let us see firing order of various engine configurations:

For 4-Cylinder engines the possible firing orders are: 1-3-4-2 or 1-2-4-3

For 3 Cylinder engine 1-3-2

8 Cylinder in-line engine 1-6-2-5-8-3-7-4

For a 6-Cylinder engine firing orders can be: 1-5-3-6-2-4 or 1-5-4-6-2-3

You might be wondering why firing order is not in sequence.Why for a four stroke engine firing order is 1-3-4-2 rather than 1-2-3-4 ? We will discuss about factors on which firing order depends in this article.


Following factors must be considered before deciding the optimum firing order of an engine. These are:

(i) Engine vibrations

(ii) Engine cooling


Consider that the cylinder number 1 of the four-cylinder engine, is fired first. A pressure generated in the cylinder number 1 will give rise to a force on the bearings. If the next cylinder fired is cylinder number 2, this imbalance in load on the two bearings would further aggravate the problem of balancing of the crankshaft vibrations & would result in severe engine vibrations. If we fire cylinder number 3 after cylinder number 1, the load may be more or less evenly distributed as cylinder 3 is far from cylinder 1 so vibrations will be distributed evenly due to symmetry of engine.

Further, consider the effect of firing sequence on engine cooling. When the first cylinder is fired its temperature increases. If the next cylinder that fires is number 2, the portion of the engine between the cylinder number 1 and 2 gets overheated.This results in uneven heating as half engine is heated.If we fire cylinder 3 after cylinder 1 then this results in equal heating of the engine which reduces thermal stress and aids in efficient cooling.

KNOW THE MEANING OF CROSS MARK AT THE END OF BOGGIE OF TRAIN !!

You might have noticed a mark X on the last bogie of a train once in a life. According to a rule, now every train must have this mark on its last bogie. Also, observe the board with letters LV written on it beside the letter X and a red light below the letter X.But do you know what that means? We will discuss about this X mark in this article.

• It indicates that wagon consisting of this letter X is the last wagon of the train.
• The Letter “X” is used during morning whereas Red light below it is used to indicate during night.
• If the last wagon of the train doesn’t contain this symbol, then it indicates that the train is in trouble and also it can be known that train is running without some wagons.
• It can easily alert the railway officials so that they can save from the accident.
• In addition, a small board with ‘LV’ (black on yellow) is often attached to the rear of the vehicle (it stands for Last Vehicle).

There are some cases where a last vehicle indication is not required — for instance, when the number of coaches or wagons in a train can be passed on to each block section after verification from the previous block section at the time the line clear indication is obtained (and with exchange of private numbers). The information is also provided to the section controllers. In some cases when working entirely within one block section, an 'LV' sign is not needed if the number of coaches or wagons is communicated by telephone to the next station.