Machine Design
A screw will be self locking, if

Friction angle is more than helix angle
Friction angle is less than helix angle
Efficiency of screw is 100%
Friction angle is equal to helix angle

ANSWER DOWNLOAD EXAMIANS APP

Machine Design
In oilness bearings

The oil film is maintained by supplying oil under pressure
Do not require external supply of lubricant
The oil film pressure is generated only by the rotation of the journal
Grease required to be applied after some intervals

ANSWER DOWNLOAD EXAMIANS APP