Mechanical Friction

·         The hydrodynamic friction is associated with the phenomena when a complete film of lubricant exists between the two bearing surfaces.

Answer: True

·         In hydrodynamic friction, the friction force does not depends on the lubricant viscosity.

Answer: In fact, in hydrodynamic friction, the friction force entirely depends on the lubricant viscosity.

·         During normal engine operation there is almost no metallic contact except between the compression piston ring and cylinder walls.

Answer: True

·         During starting of the engine, the journal bearings operate in ____________ friction.

Answer: partial-film

·         The ____________ friction is due to rolling motion between the two surfaces.

Answer: rolling

·         Ball and roller bearings and tappet rollers are subjected to rolling friction.

Answer: True

·         Rolling friction coefficient is ____________ than journal bearing friction coefficient during starting and initial running of engine.

Answer: lower

·         A circular cylindrical shaft called journal rotates against a cylindrical surface called the bearing.

Answer: True

·         Total friction is negligible compared to rolling friction.

Answer: No, but rolling friction is negligible compared to total friction.

·         The mechanical friction ___________ with increase in speed.

Answer: Mechanical friction is directly proportional to engine speed, so the mechanical friction increases with increase in speed.