i8o

MODERN PAPER-MAKING

wire on which the stuff and water are evenly spread and formed into paper.
For this purpose they must be accurately levelled from side to side and to
each other, and at even* renewal of the wire, examined and thoroughly cleaned.
Great care should be taken in replacing them in their proper order. They

are usually numbered for conveni-
ence. A safe place should be
selected for them to lie until they
are put back.

Although paper machines will
run satisfactorily and make good
paper with stationary tube rolls, it
is usual to have these rolls fitted
with very free-running bearings.
If the bearings are ordinary brass,
they should be kept well and
regularly greased or oiled. Ball
bearings are now available which
will withstand the conditions and
keep out water, and they are in
every case to be recommended.

It is important that the tube
rolls should be of a sufficient dia-
meter to enable the usual speed to
be run, without the throwing of
water from the rolls. In some
cases it is necessary to put doctors
on the tube rolls, or baffle plates,
to catch the water thrown off by
the roll and prevent it being taken
up to the wire again.

Their second function is to draw
water from the sheet. A layer of
water forms on the under side of
the wire, a tube roll rubs or drains
it aw&y, leaving a partial vacuum in each minute pore of the wire. This imme-
diatseiy fills wtix water and is emptied by the next roll. Thus it will be seen
that tbe number of tube rolls has a definite relation to the length of the wire.

A short wire, closely tubed, can deal with wet stuff, as far as extraction of
water k cooccraecl Beady, if not quite, as well as a longer wire with the same
number oŁtei» rolk

[James Bertram md Sons Ltd.
Be. 64*—LATEST Tm SHMTC MOTION, WITH VAWABIE
SHBBD MOTOR pot SPEED ALTERATION
The stroke is altered by the hand wheel