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Determining the Main Bearing

Presented by Brian KhalighiVice President, Engineering

The Robbins Company

Standard Indication of Load Cases for Calculation

of Rating Life (L10) of TBM Main Bearings

Life on a TBM

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Introduction

Outline

OUTLINE

e n on o a ng ys em Rating Life Equation Cutterhead Speed Equation Summary of Main Bearing Loads Definition of TBM Main Bearing

Safety Factor Typical Bearing Load Assumptions

by TBM Type Conclusions

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Standardized method of indicating main

bearing load assumptions

Introduction

INTRODUCTION

ear ng ves o ere y var ousmanufacturers

Provides guidance for evaluation TBM types discussed:

Gripper Single shield and double shield (SS, DS) Earth pressure balance (EPB) Slurry (STBM)

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About Rating Life (L 10)

About Rating Life (L 10)

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DEFINITION

Definition of Rating Life ( L10 )

Defined in ISO recommendation R281:

The rating life of a sufficiently large number of identical bearings is expressed by the number of revolutions (or number of hours at constant speed) reached or exceeded by 90% of this

bearing group before the first signs of material fatigue appear.

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The Rating Life ( L10 ) Equation

EQUATION

THE RATING LIFE (L10 ) EQUATION

L10 = (C/P) k

L10: rating life in [10 6 revolutions] C: dynamic load bearing capacity

of the bearing in [kN] P: applied load in [kN] K: for roller bearings = 10/3

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Cutterhead SpeedCUTTERHEAD SPEED

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TBM Main Bearing Safety Factor

SAFETY FACTORS

The safety factor of a TBM mainbearing is defined as the relationbetween calculated bearing L 10lifetime in hours, and the

anticipated cutterhead operationtime for the project

For used bearings, the remaininglifetime should be considered

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TYPICAL BEARING LOAD ASSUMPTIONS

Typical Bearing LoadAssumptions as Used in the

Industry

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Hard Rock TBM (Gripper, SS, DS)

TYPICAL BEARING LOAD ASSUMPTIONS

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Remarks

TYPICAL BEARING LOAD ASSUMPTIONS

CH: e cu er ea rus s e ne as o a o sc cu ers x sccutter load capacity

Fr: the operational radial load F r (resulting from steering loads) is definedas 2 x disc cutter load capacity

The anticipated cutterhead torque T c is only required in case a gearcalculation should be performed

In load cases LC I and LC II, the dynamic roller pressure allowable must notbe exceeded

In load cases LC III, the static roller pressure allowable may not beexceeded

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QUESTIONS

QUESTIONS?