Rail joint. A funny incident from life Why do they leave a gap between the rails

18.05.2019

rail joint

rail joint- the junction of two rails on the railway. The joint necessarily includes a gap for free elongation of the rails when the temperature changes. The rails are kept from shifting by a metal (in insulating joints - a dielectric plate (textolite, metal composite), insulated from the rails with a set of side and end gaskets and bushings) plate / overlay pressed against the rails by 4-6 bolts on both sides. In a classic rail joint, the holes for fixing bolts in the plates have an oblong shape through one hole, i.e. of the six holes, three are oblong. Holes opposite each other in the linings on different sides of the joint are obtained different shapes- the round hole is opposite the oval one. The oval hole has this shape due to the special oval part of the head of the butt bolts, which fit into the oval hole and do not rotate when the butt bolt nut is tightened. The holes in the rails for butt bolts are larger than the bolt diameter by 20 mm, this is done in order to ensure the movement of the end of the rail during thermal elongation / shortening of the rail without causing a shear force in the bolts. Blind gap (lack of gap) indicates the occurrence of thermal compressive stress in the rail, which can lead to thermal overshoot of the track. A gap of more than 20 mm indicates the occurrence of a shear force in the butt bolts. If the gap is more than 20 mm, the speed of trains along the track section with such a gap is limited. If the gap is more than 35 mm, the movement of trains on the section is closed until the joint malfunction is eliminated.

Solving the thermal gap problem made it possible to create a so-called seamless path. It is used on the railroad. On the Moscow Metro, on the flyover part of the Butovskaya line, work was carried out on the construction of a seamless track. This technology somewhat reduces energy losses and rail wear, and also significantly reduces the number of defects that occur in the rail metal when hitting a butt joint, eliminates the problem of splashes under the joints and significantly reduces the noise level. Seamless tracks are also often used on tram tracks. The use of a seamless track refers to resource-saving technologies in the track industry.

To create (tie) a joint into a lash or link, two machines are used - a rail-cutting machine and a rail-drilling machine. The rail cutter can be in the form of a large diameter cutting wheel, like an angle grinder, driven by its own gasoline engine and a machine with a progressively moving blade. Holes for butt bolts are drilled drilling machine, a drill with a hard-alloy tip. The last two types of machines are powered by electricity generated by a portable power station "ZhES".

In railway terminology, the pronunciation of the word "joint" in plural. The emphasis is always placed on the vowel following the letter "to", for example, "Joints", "at the joints".

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See what "Rail joint" is in other dictionaries:

rail joint- The junction of the rails in the rail thread by welding or using butt plates and bolts. Source: SP 119.13330.2012: 1520 mm gauge railways ... Dictionary-reference book of terms of normative and technical documentation

insulated rail joint- — [Ya.N. Luginsky, M.S. Fezi Zhilinskaya, Yu.S. Kabirov. English Russian Dictionary of Electrical Engineering and Power Engineering, Moscow, 1999] Electrical engineering topics, basic concepts EN insulated rail joint ... Technical Translator's Handbook

Rail junction A rail junction is the junction of two rails on a railway. The joint necessarily includes a gap for free elongation of the rails when the temperature changes. Rails hold ... Wikipedia

Joint Joint (rail) joint between rails in a railway track, subway track, tramway Joint (railway) docking station of neighboring departments or neighboring railways, also docking station of current generation (at ... ... Wikipedia


Remember: Conclusion is the “answer” to the purpose of the work! Table 7.1 - Requirements for writing a conclusion
	What should be in the output	How to write it
	What has been done at work	Write what exactly is done in the work. In that work…… (What has been done? Read again the purpose of the work)
	How it's done	Brief description of the experiment: what specific values are determined using which devices, what quantities (including errors) are calculated by the formulas (formulas do not need to be rewritten!)
	What is received	Write down the result (obtained values, their errors - with units )
	Result Analysis	Analyze the result. To do this, compare the experimental value of the coefficient of linear thermal expansion for a given substance a exp with table value a table And give your rating the results obtained. For example: ...values agree well, (either satisfactory or inconsistent). Write what is the reason for the discrepancy between the experimental value (obtained in this work) and the tabular value.

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Rewrite questions and task conditions your option.

The tables in Appendix A provide the necessary reference material.

Tasks of increased complexity are marked * (for a mark of "4") and ** (for a "5")

Option 1

1.1 Railway rail at a temperature of 0 0 C has a length of 50m. Determine how much the length of the rail will change when heated to 30 0 C.

1.2 Why between rails railway leave gaps in the joints, but do not do this for tram joints?

1.3* Why do we use the red scale when reading the indicator? What would you have to do if there was no red scale?

1.4** Will the result of the laboratory work change if the solid metal rod in the instrument is replaced with a tube of the same material? Explain.

Option 2

2.1 The length of a steel railway bridge is 1000 m at 0 0 C. Determine the length of the bridge in winter at a temperature of -30 0 C.

2.2 How does the density of a substance change when heated? Explain.

2.3* Why does a steel bolt screw easily into a copper nut when both are heated?

2.4** Why do cracks appear in the enamel with a sharp change in the temperature of enamelware?

Option 3

3.1 An electric current is passed through a copper wire 6 m long. By how many degrees did the wire heat up if it lengthened by 4mm.

3.2 Explain the thermal expansion of bodies in terms of molecular kinetic theory.

3.3*Why are glass vessels heated to high temperatures made of thin glass?

3.4** Why does concrete not separate from iron when heating and cooling reinforced concrete?

Option 4

4.1 Length glass tube at 0 0 C it is 120 cm. Find its length at 100 0 C.

4.2 Will the equilibrium of the sensitive balance be disturbed if one arm of the rocker arm is heated?

4.3 * What requirements should the material of the electrodes soldered into the glass bulb of an incandescent lamp satisfy?

4.4** How will the inner diameter of a metal ring change when it is heated? Explain.

1. Why does cold glass crack when boiling water is dropped on it? 2. Why are gaps left between the rails when laying railway and tram tracks? 3. Why, during the transportation of fuel from the northern regions to the southern railway tanks, in which it is transported, are they not filled to the top?

Answers:

All this is due to the fact that when heated, the body expands. 1) Cold glass expands rapidly, and because it is not ductile, but brittle, it cracks. 2) In the heat, the rails expand and lengthen. If you leave no gaps, the path will curve. 3) Fuel also expands when heated. If the tank is filled to the top, then the fuel can, when expanding, tear off the tank hatch or break the tank altogether.