Volume 183001

Mechanics / By Henry Kater and Dionysius Lardner.

  • Henry Kater
Date:
1830
Catalogue details

Licence: Public Domain Mark

Credit: Mechanics / By Henry Kater and Dionysius Lardner. Source: Wellcome Collection.

    215/408 page 185
    rough, either by facing them with buff leather, or with wood cut across the grain. This method is sometimes used in spinning machinery, where one large buffed wheel, placed in a horizontal position, revolves in con- tact with several small buffed rollers, each roller com- municating motion to a spindle. The position of the wheel W, and the rollers RR, &c., are represented in ~ fig. 102. Each roller can be thrown out of contact with the wheel, and restored to it at pleasure. The communication of motion between wheels and axles by friction has the advantage of great smoothness and evenness, and of proceeding with little noise; but this method can only be used in cases where the resistance is not very considerable, and therefore is seldom adopted in works on a large scale. Dr. Gregory mentions an in- stance of a saw mill at Southampton, where the wheels act upon each other by the contact of the end grain of wood. The machinery makes very little noise, and wears very well, having been used not less than 20 years. (259.) The most usual method of transmitting mo- tion through a train of wheel-work is by the formation of teeth upon their circumferences, so that these in« dentures of each wheel fall between the corresponding ones of that in which it works, and ensure the action so long as the strain is not so great as to fracture the tooth. In the formation of teeth very minute attention must be given to their figure, in order that the motion may be communicated from wheel to wheel with smoothness and uniformity. This can only be accomplished by shaping the teeth according to curves of a peculiar kind, which mathematicians have invented, and assigned rules for drawing. The ill consequences of neglecting this will be very apparent, by considering the nature of the action which would be produced if the teeth were formed of square projecting pins, as in fig.103. When the tooth A comes into contact with B, it acts obliquely upon it, and, as it moves, the corner of B slides upon the
    digitised image 1
    digitised image 2
    digitised image 3