164

MODERN PAPER-MAKING

thickness of the stuff stream can be regulated either as a whole, across the full
width of the sheet, or locally at any point on the sheet, where for some cause
or other there may be a thick or thin place.
The whole stuff gate may be opened or closed at one operation by turning
the hand wheel on the front side. The local adjustment is done by vertical
screw-threaded spindles secured to the flexible bronze upper lip of the discharge
opening (Fig. 52). The adjustments are simple, and can be made by the
machineman while the machine is running, and without having to use pieces

[Renold Marsh Ltd.

fig. 51.—Vorra shoeless flow Box
of paper on the slice or bits of lead on the apron, or any other troublesome and
unsatisfactory makeshifts.
A revolving, perforated copper roll, seen in the illustration (Fig. 51), is
placed just behind the discharge opening, and helps to release air bubbles; it
also keeps the fibres in a state of agitation, and therefore properly suspended in
the water.
The absence of an apron altogether on fast machines, and the use of only
a very narrow one on slow machines, saves a great deal of drag on the wire,
apart from dispensing altogether with the numerous troubles caused on all
machines by aprons, no matter how well they may be fitted.