SUPER-CALENDER

305

with the iron rolls for the second half of its passage, thus giving an equal\fkish
both sides. \^ *

The iron rolls are highly burnished and fitted for steam heating. The
bottom roll is made greater in diameter than the other rolls, in order to sustain
the weight of those above it. The other iron rolls are less in diameter than
the paper rolls. As all rolls 'give' under pressure, the calender rolls require

FIG. 132.—LARGE SUPE&-CAIENDER FOR NEWSPRINT

[Walwkys (Bury), Ltd.

to be very carefully cambered. The weight of the rolls of an eight-roll calender
resting on the bottom one would be about 9 tons for a po-inch machine and
about 30 tons with/weights full on. This size would take 25 to 50 Lp. at
350 feet per minute, according to the degree of finish and the quality and sub-
stance of the paper being treated. The drive is either from the bottom roll or
the third from die bottom. In machines with sixteen rolls or more, the seventh
from the bottom is the driver, top and bottom rolls being assisted with belt
drive, to reduce slip or skid which is very destructive to the strength and
bulk of the paper. When not in use the rolls should be relieved of the lever