Pit stop for changing parts

TBM Herrenknecht S-771 “Irina” was equal in penetration to its “neighbor Herrenknecht S-770 “Tatyana”. Two shields are working on the extension of the section of the Lyublinsko-Dmitrovskaya metro line between Lianozovo and Fiztekh.

Timely replacement of cutting tools helps to overcome underground rocks. Our correspondent found out how this procedure occurs.

TBM operator SMU-12 Andrey Shibaev and block paver operator SMU-12 Sergey Pechenkin in the Irina cabin

At the end of July, the Herrenknecht S-771 Irina shield made a stop on the underground route between the Lianozovo and Fiztekh stations. Having traveled almost 1.8 kilometers, the shield required replacement of the cutting tools - cutters (these parts are used in hard rocks. Operating principle: by rolling, the cutter creates a load on the rock in addition to the cutting effect, due to which it destroys the rock), buckets and standard cutters on the rotor.

“This is a planned stop,” explained Ivan Roman, a mechanic at section No. 4 of SMU-12. – The frequency of changing parts depends on the rock in which the shield is used. Nowadays it is mostly loam; there is no limestone at the current level. On the track, cutting tools are inspected every 500 meters.

According to him, there may be stops a little more often - it depends on whether the TBM pilot noticed any problems. In such cases, the mechanized complex becomes more difficult to manage. The integrated team involved in the operation of the shield carries out the necessary examination.

First, the rotor is cleaned of rock. In particular, the team rotates the beams and seats of the TBM rotor. The next stage is the diagnosis of the cutting tool.

“If it is not very worn out - by 20 percent, then the replacement of parts will be partial,” adds Ivan Roman.

Electrical mechanics, welders, repair mechanics - 7-8 people in total - change the necessary parts.

The operation itself must be carried out quickly and expertly - a couple or three days are allotted for all actions. This time the Herrenknecht S-771 was put in order in two and a half.

“After stopping and replacing the cutting tool, the penetration speed of the shield picks up slowly,” he explains. – Already at its peak, the TBM can lay 8-10 rings per day – that’s about 12 meters.

The current stop of the shield is not the first. Previous pit stops were associated with the need to increase the power cables that supply the mechanized complex with electricity. This is done every 250 meters. Such work takes from two to four hours and occurs approximately every month of excavation.

“In total, the Irina TBM stopped six times, each of them is prescribed in the regulations,” says the site mechanic. – All parts are ordered in advance after the machine has been diagnosed. They are delivered along part of the tunnel that has been passed.

“Irina” was given a year to lay a 2.3-kilometer underground route between the future stations of the Lyublinsko-Dmitrovskaya metro line. However, the brigade promises to cope even earlier - closer to October.