Basic Principles MCQ Quiz in मल्याळम - Objective Question with Answer for Basic Principles - സൗജന്യ PDF ഡൗൺലോഡ് ചെയ്യുക

Explanation:

Superelevation:

(i) It is the difference between the height of outer rail and inner rail on curve.

(ii) It is also known as cant.

(iii) Inner rail is taken as the reference rail and w.r.t. inner rail, outer rail is raised.

Formula for superelevation:

$e=\frac{G{V}^2}{127R}$

Where,

G = Gauge

V = Speed (in kmph)

R = Radius (in m)

Maximum value of cant (e_max):

So, e_max for BG Track is 16.5 cm = 165 mm

Objective of Providing a superelevation:

(i) To neutralize the effect of centrifugal force.

(ii) Achieve equal distribution of wheel loads.

(iii) To improve the comfort level of passengers.

(iv) To avoid jerk when rolling stock moves from a straight section to a curved section.

Concept:

The gauge of a railway track is defined as the clear distance between the inner or running faces of two-track rails.

The distance between the inner faces of a pair of wheels is called the wheel gauge.

The following table gives the length of the rail for different types of gauges.

Indian Railways has standardized a rail length of 13 m (previously 12.8 m) for broad gauge and 12 m (previously 11.8 m) for MG and NG tracks. 

Important Points

Width of the Gauges

Theoretically, the longer the rail, the lesser the number of joints and fittings required, and the lesser the cost of construction and maintenance. Longer rails are economical and provide smooth and comfortable rides. The length of a rail is, however, restricted due to the following factors.

(a) Lack of facilities for transport of longer rails, particularly on curves.

(b) Difficulties in manufacturing very long rails.

(c) Difficulties in acquiring bigger expansion joints for long rails.

(d) Heavy internal thermal stresses in long rails.

Explanation:

Fish plates are usually made of High carbon steel.

The name ‘fish plate’ derives from the fish-shaped section of this fitting.

The function of a fish plate is to hold two rails together in both the horizontal and vertical planes. Fish plates are manufactured using a special type of steel (Indian Railways specification T-1/57) with the composition given below:

a) Carbon: 0.30–0.42%

b) Manganese: not more than 0.6%

c) Silicon: not more than 0.15%

d) Sulphur and phosphorous: not more than 0.06%

The number of bolts per fish plate is 4

The steel used for fishplates should have a minimum tensile strength of 5.58 to 6.51 t/cm² with a minimum elongation of 20 %.

Fish plates are designed to have roughly the same strength as the rail section, and as such the section area of two fish plates connecting the rail, ends is kept about the same as that of the rail section.

The standard depth of ballast is generally taken as 25 cm. However, it can be increased to 30 cm for higher axle load.

Dimension of ballast for different gauges are given below:

Kindly Refer: 

CHAPTER II, THE MAINTENANCE OF PERMANENT WAY, Part ‘F’, BALLAST AND BALLAST DEPOTS

http://122.252.243.98/Departments/openline/cnm/Manuals/Enginfo/mauals/pwm86/Ch/ch_2f.html

The material placed in between the sleeper and the top of the formation is known as the ballast. Materials of which ballast is composed is known as ballast cushion.

Ballast cushion on the curved track is depicted below:

Dog spikes are used to hold FF rails to a wooden sleeper and are simply stout nails to hold rail flanges with timber sleepers.

Dog bolts are used when sleepers rest directly on a girder. They are fastened to top flange of girder by dog bolts.

C.I. chairs are used for holding double headed and bull headed rails and they are then fixed to sleepers by round spikes.

Switch: It consists of a tongue rail and a stock rail as can be observed in the figure above.

A set of switches consist of a left-hand switch and a right-hand switch, such set of switches is known as the points.

Explanation:

Switch: 

It consists of a tongue rail and a stock rail with the necessary connections and fittings as can be observed in the figure above.

A set of switches consist of a left-hand switch and a right-hand switch, such a set of switches is known as the points.

The combination of points and crossing is known as turnout.

Explanation

The followings are some methods for reducing the wear of rails:

1. Use of special alloy steel.
2. Good maintenance of the track.
3. Reduction of expansion gap:  It is done by packing the sleepers at the joints and tightening fish bolts. This will result in the reduction of wear at the end of the rails.
4. Reduction of the number of joints.
5. Exchange of inner and outer rail on a curve: It is done on curves, where there is heavy wear at the top of the head of the inner rail and heavy wear of the side of the head of the outer rail then the top wear rail is exchanged with the side wear rail and thereby the life of rail is increased.
6. Use of lubricating oil on the side of the head of rails (gauge face).
7. By coning of the wheel.
8. Tilting of rails.

Explanation:

High water absorption makes ballast weak and reduces its crushing strength.

Note:

As per IS 2386 -1963: Water Absorption should not be more than 1 %.

For higher modulus value, the ballast will provide better elasticity to the railway track and increased ability to bear loads.

For the higher stability, the ballast can hold sleeper in position and will provide better resistance to vibrations, shocks, and impact loading.

Due to high resilience, ballast can resist the dynamic behaviour of train i.e. it can store or withstand high impact energy.