Main Bearing
AssemblyA three-row roller bearing several meters in diameter that lets the cutterhead turn while carrying its thrust, its weight and the overturning moment from uneven face loads. Replacing it underground is a major job, so it is sized and sealed to last the whole drive; makers keep its diameter as large as the tunnel allows, because bearing life drops when it is small relative to the bore. A full specification article for this item is being written. Meanwhile its bill of materials and connections are below.
Bill of materials for Main Bearing
4 top-level lines as of r193939| # | Item / sub-assembly | Part no. | Qty/assy | Ext. qty | Parts | Type |
|---|---|---|---|---|---|---|
| 1 | Main Bearing Rings | main-beam-tbm-bearing-rings | 1× | 1 | · | part |
| 2 | Main Thrust Roller Row | main-beam-tbm-thrust-roller-row | 1× | 1 | · | part |
| 3 | Reverse Thrust Roller Row | main-beam-tbm-reverse-thrust-roller-row | 1× | 1 | · | part |
| 4 | Radial Roller Row | main-beam-tbm-radial-roller-row | 1× | 1 | · | part |