MODERN PAPER-MAKING
while the strainer is working, and the vibrator may be removed from the
bottom of the vat without disturbing the drum.
All the driving mechanism, is entirely enclosed and works in oil, so that no
water can get near it.
The pulp enters the vat below the level of the diaphragm, so that heavy
particles and dirt are inclined to stay down in the lowest part of the trough.
The stuff is pushed upwards against the lowest part of the drum, and passes

[James Bertram and Sons Ltd.
fig. 48.—the 'lhth walk* full-drum inward-flow revolving strainer
through into the drum, from which it is poured out at the ends into the shute,
which takes it to the breast box.
A strong shower of water is played against the slits at the top of the drum
to clean it. This strainer is giving universal satisfaction, and possesses distinct
advantages over most of the other inward-flow strainers, not the least of which
is its freedom from a large collection of exposed working parts, belts, etc.
One of the latest strainers, and one which is giving great satisfaction in
mills using short-fibred stock, is the Bird screen (Fig. 49). THs is a
large inward-flow strainer capable of passing a very large amount of stuff.