477) The railway carriage couplings have

478) A shaft is subjected to

479) When the lubricant is forced between the journal and the bearing by external pressure, the bearing is called hydrostatic lubricated bearing.

480) The buttress threads have low frictional resistance characteristic of the square threads and have the same strength of V-threads.

481) The tension on the slack side of the belt is __________ the tension on the tight side of the belt.