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.