Arrow cut

The wheels of the moving train, pushing the arrows allocated to the wit, move it to the frame rail. The assigned wit carries with it a pressed one, which is diverted from its frame rail. There is a danger for subsequent movement in the direction of the arrow in the opposite direction. Cutting the arrow leads to a curvature and fracture of the wits. To exclude damage, closing devices (turnout electric locks, contactors, etc.) are made cut-out (not damaged during the cut).

On the railway, an arrow incision is classified as a marriage case at work . However, in the urban tram system this is a regular situation, it is through the explosion of the arrows that the rolling stock moves from the side track to the main one. The design of the transfer mechanism of the tram arrow differs from that for the railway arrow and works normally in this mode.

The main reasons leading to an arrow cut are:

• Violation of the rules of action or the rules of negotiations , and, as a result, the position of the arrow does not correspond to the route of the rolling stock and the crest of the bandage of the wheel pair with the rolling movement of the rolling stock passed between the pressed wit and the frame rail
• In case of a loose fit of the wit to the frame rail (4 mm or more), the crest of the bandage of the wheel pair at the entrance to the wit falls (cuts) between the wit and the frame rail

In the case of an arrow explosion, a signal is sent to the centralization post ( station duty ), which excludes the possibility of controlling this arrow until damage is repaired. The station attendant can determine the arrow incision according to the following criteria ^[1] :

• the bell rings
• the red light is on
• the electric control lamps of the plus and minus position of the arrow do not light when the arrow button (turn of the handle) of the plus or minus position is pressed
• the electric backlight does not show in which position the arrow is (arrows)
• the traffic light is blocked for the route into which the cut arrow enters or for the route in which it is a guard

Cases of cuts in anti-wool motion are also known. In case of violation of the standards for turnouts (non-adherence of the wit to the frame rail) and wheelsets, an anti-wool incision is possible. In the standards for the content of turnouts, there is a parameter regulating the fit of the wit to the frame rail (there is a special simple template “ KOR ” - “control wit-frame” to control fit). In rail, an anti-wool incision usually leads to derailment . But it happens very rarely.

One example of an anti-wool incision is the Eshed disaster , where the turn of the arrow, which caused the rear wheels of the third car to move to the adjacent track and out of the rails of the remaining cars, occurred due to the impact on the wit of the wheels of the front carriage, which went off the rail because of a burst bandage on one of them.

It is possible that a catastrophe occurred in the Moscow metro on July 15, 2014 ^{[2] [3]} , due to the anti-woolly explosion of the arrow, but final confirmation of this can be obtained only after the investigation is completed ^[4] .

• Classification of railway traffic safety violations

• Rail transport: Encyclopedia / Ch. ed. N. S. Konarev . - M .: Big Russian Encyclopedia , 1994. - S. 62. - ISBN 5-85270-115-7 .