Fig. 48.—Plan and Sectional Elevation of a “Hollander.”
Developments in Beating Engines.—Since the introduction of the Hollander beating engine, about A.D. 1670, other types of beater almost too numerous to mention have been devised to supersede it, but the fact remains that the principle of the original Hollander and its general design are still adhered to in the engines used by paper-makers for high-class work.
The alterations and improvements which have taken place during the last fifty years relate chiefly to the modifications naturally arising from the introduction of fibres not requiring such drastic treatment as rags.
The machines now in use for reducing half-stuff to beaten pulp ready for the paper machine may be classified as follows:—
(1) Beaters of the Hollander type, in which the circulation of the pulp in the engine and the actual beating process are both effected by the beater roll.
(2) Beaters of the circulator type, in which the movement of the pulp is maintained by a special contrivance, and the beater roll used only for beating.
(3) Beaters of the stone roll type in which the roll and bedplate are either or both composed of stone, granite, or similar non-metallic substance.
(4) Refiners, containing conical shaped beater rolls working in a conical shell fitted with stationary knives.