4. The friction varies as the temperature rises, and as the viscosity of the lubricant is thus decreased (80).
43. The Methods of Reducing Waste of Energy Caused by Friction in time keeping mechanisms are based upon a few simple principles. It is evident that to make the work and power so lost a minimum, it is necessary to adopt the following precautions:
1. Proper choice of materials for rubbing surfaces (29-32).
2. Smooth finish and symmetrical shape of surfaces in contact (29-32 and 38).
3. The use of a lubricant the viscosity of which is adapted to the pressure between the bearing surfaces (80).
4. The best methods for retaining the lubricant at the places required, and for providing for a continual supply of the lubricant.
5. The bearing surfaces of such proportions that the lubricant will not be expelled at normal pressure.
6. The reducing of the diameters of all journals, shoulders and pivots, to the smallest size compatible with the foregoing conditions, and with the stresses they are expected to sustain, thus reducing the space, through which the fluid friction acts, to a minimum (40); as well as reducing the distance from the axis of the arbor or pinion at which the friction, both solid and fluid, acts. The work done is independent of the length of the journal; except as it may modify pressure, and thus the coefficient of friction.
7. Proper fitting of bearing surfaces (37).
8. The reducing of the rubbing surfaces in escapements as much as the nature of the materials will allow without abrasion in the course of time (55).