BEATERS - 85

potching stick, or only moves very slowly. The shape of the trough is shown
in Fig. 16, and paper-makers will see at once that the 'dead spots' in their beaters,
which they have often had to fill up with cement or concrete, have been entirely
eliminated.

The height of the trough is arranged to coincide with the general height
of stuff as it travels round the beater, and it is low in front of the roll and high
behind the backfall.

The roll itself is very heavy (9 to 10 tons in a looo-lk beater), and the roll
bars are equally spaced and not set in clumps. The reason for the heavy roll
is to give pressure on the bed-plate, and to prevent jumping and vibration
when lumps of stuff pass through, while the fine adjustment provided for
lowering the roll prevents all risk of the roll being too suddenly or heavily let
down on to the bed-plate. A heavy roll is better for beating strong stuff,

[Bertram Ltd.
FIG. 26.—SCIENNES PATENT BEATING ENGINE, SHOWING AUTOMATIC CONTROL GEAR
which has to be well fibrillated, than a light roll, for it is steady and can be
kept at the correct distance from the bed-plate all the time.
As it is impossible for a beaterman, who has a battery of beaters to super-
vise, to operate them all in exactly the same way each time, an automatic
operating gear has been fitted.
The front main lever is operated by compound levers, and the weight L>
adjusted by hand wheel and screw, so that any desired pressure may be applied.
The pressure may be maintained constant from start to finish if need be, but
can be easily adjusted to suit requirements.
The bars, as mentioned above, are equally spaced, and not clumped, as has
been the usual practice for many years. The reason for this is obvious, for,
as every beaterman knows, the first bar of the clump carried most of the stuff
and the following bars not enough. Well-separated single bars, especially for
long stuff, are the best.