Page 8 - Tribology in Machine Design

Contents vii

4.3. Friction in screws with a square thread 103
4.3.1. Application of a threaded screw in a jack 105
4.4. Friction in screws with a triangular thread 109
4.5. Plate clutch - mechanism of operation 111
4.6. Cone clutch - mechanism of operation 114
4.6.1. Driving torque 115
4.7. Rim clutch - mechanism of operation 116
4.7.1. Equilibrium conditions 117
4.7.2. Auxiliary mechanisms 119
4.7.3. Power transmission rating 120
4.8. Centrifugal clutch - mechanism of operation 120
4.9. Boundary lubricated sliding bearings 121
4.9.1. Axially loaded bearings 123
4.9.2. Pivot and collar bearings 124
4.10. Drives utilizing friction force 127
4.10.1. Belt drive 128
4.10.2. Mechanism of action 129
4.10.3. Power transmission rating 132
4.10.4. Relationship between belt tension and modulus 133
4.10.5. V-belt and rope drives 134
4.11. Frictional aspects of brake design 136
4.11.1. The band brake 136
4.11.2. The curved brake block 138
4.11.3. The band and block brake 144
4.12. The role of friction in the propulsion and the braking of
vehicles 145
4.13. Tractive resistance 150
4.14. Pneumatic tyres 151
4.14.1. Creep of an automobile tyre 152
4.14.2. Transverse tangential forces 152
4.14.3. Functions of the tyre in vehicle application 154
4.14.4. Design features of the tyre surface 154
4.14.5. The mechanism of rolling and sliding 155
4.14.6. Tyre performance on a wet road surface 157
4.14.7. The development of tyres with improved
performance 159
4.15. Tribodesign aspects of mechanical seals 160
4.15.1. Operation fundamentals 161
4.15.2. Utilization of surface tension 162
4.15.3. Utilization of viscosity 162
4.15.4. Utilization of hydrodynamic action 163
4.15.5. Labyrinth seals 164
4.15.6. Wear in mechanical seals 164
4.15.7. Parameters affecting wear 168
4.15.8. Analytical models of wear 169
4.15.9. Parameters defining performance limits 170
4.15.10. Material aspects of seal design 170