Читать книгу A Catechism of the Steam Engine - C.E. John Bourne - Страница 12
ОглавлениеA.--Various experiments have been made by Mr. Summers of Southampton to ascertain the friction of brass surfaces sliding upon each other in salt water, with the view of finding the power required for moving sluice doors for lock gates and for other similar purposes. The surfaces were planed as true and smooth as the planing machine would make them, but were not filed or scraped, and the result was as follows:
| Area of slide rubbing surface. | Weight or pressure on rubbing surface. | Power required to move the slide slowly in muddy salt water, kept stirred up. |
| Sq. in. | Lb. | Lb. |
| 8 | 56 | 21.5 |
| " | 112 | 44. |
| " | 168 | 65.5 |
| " | 224 | 88.5 |
| " | 336 | 140.5 |
| " | 448 | 170.75 |
These results were the average of eight fair trials; in each case, the sliding surfaces were totally immersed in muddy salt water, and although the apparatus used for drawing the slide along was not very delicately fitted up, the power required may be considered as a sufficient approximation for practical purposes.
It appears from these experiments, that rough surfaces follow the same law as regards friction that is followed by smooth, for in each case the friction increases directly as the pressure.
