Coning of wheels-What is coning of wheels?

Coning of wheels is an interesting topic in railway engineering. The tread or rim or flanges of locomotive wheels is made in the shape of a cone with a slope of about 1 in 20. This is known as coning of wheels. The coning of wheels is done primarily to keep the vehicle in a central position with respect to the track. In this blog, we will see the theory of the coming of rail wheels, starting from what is coning of wheels.

What is coning of wheels?

Let’s see what is coning of wheels step by step.

• The space between the inner borders of wheel rims is by and large kept less than the measurement of the track.
• This results in a gap between the wheel rims and running ends of the rail which is approximately equal to 1cm. (2/8 on both sides).
• More often than not, the tread of the wheels is perfectly at the dead centre of the beginning of the rail, since the wheel is chamfered to keep it in this middle position involuntarily.
• Thus, in coning of the wheel the tread or rim of wheels of railway vehicles is made in the shape of a cone with a slope of about 1 in 20.
• It maintains the vehicle in the central position with respect to the track.
• On a straight track, portions of wheels running on the track have the same diameter.
• While on the curved path, the outer wheel has to cover a larger distance than the inner wheel. Thus, the portions of wheels running on the track have different diameters which help in the smooth running of wheels.

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Theory of coning of wheel

• We have seen what is coning of _wheel through some easy-read bullet points. Let me do the same to learn the theory behind coning of rail wheels.
• On a railway level track, the moment the hinge locomotes towards one rail, the wheel tread width above the rail steps-u but reduces over the other rail.
• This forbids auxiliary movement and the hinge pulls back to its original position.
• This is possible only if the diameters on both rails are equal and the pressure on both rails is also equal.
• On a coiled path, because of the rigidity of the wheel bottom, either of the wheels has to slip by a measure equal to the differentiation of length.
• Because both wheels must travel the same distance, one wheel will slide. Further side movement is halted due to sliding resistance. If the coning had not been present, the side movement would have continued, and the flange of the wheel would have made contact with the side of the rail, resulting in uncomfortable riding.
• Or else, the axle has to move outward a bit so that a tread with a longer diameter is formed over the outer rail where, whereas a slighter diameter tread is formed over the inner rail.

Also read: Applications of Intelligent transportation system- everything you want to know

Calculation of coning of wheel in railways

If the diameter of the tread on both rails is equal, then

Slip=α (R₂-R₁),

The outer radius, R2=R+C/2

Inner radius, R1= R-G/2

G= Gauge

α= Angle at centre in radians

 Therefore, slip= alpha X G

α ⁰ = Angle centre in degrees about 1 degree

α ⁰ Slip= 0.029 (roughly for 1 degree of central angle)

• Therefore, the slip is about 0.029m per degree of the central angle.
• Chamfering of wheels on bends is not useful as the principal axle if owing to centrifugal force proceeds towards the outward rail the back axle will precede towards the inside rail and the complete benefit of coning wheels cannot be availed.
• Put differently, there will be no free sidelong movement of wheels.
• This results in the disadvantage of the outer rail will have more pressure while the inner rail will have lesser pressure.
• Owing to the central strength, the parallel components incline to turn the rail out and the gauge has to broaden tendency.
• Due to this condition if the void sleepers have no base plate beneath the edge of the rail they will be damaged. In order to get rid of or minimize the supra-mentioned faults “angling of rails” is done.
• When the rails are tilted then the base plate or sleeper is not placed horizontally. It is laid at a slope of 1 in 20 towards the inner side.

Advantages of coning of wheels

1. Smooth riding- helps the vehicle to negotiate curves smoothly
2. Reduces wear and tear of wheel flanges. Damage is caused because of the friction action of rims with the inner faces of the rail top.
3. It gives an option for lateral drift of the hinge with its wheels
4. It prevents, to some extent, the slipping of the wheels

We have seen the advantages. Let’s see the disadvantages of coning of wheels now.

Disadvantages of coning of wheels

1. The pressure on the horizontal component of force near the inner edge of the outer rail has a tendency to wear the rail quickly
2. The horizontal component has to turn the rail outwards and hence the gauges may be widened.
3. If no base plates are provided, sleepers under the outer edge of the rail may be damaged

Also read: Intelligent transportation system: A comprehensive approach to its components

So, that was it about coning of wheels. Hope you find the article useful. Tell us your thoughts in the comments.

Happy learning!