ured. The gudgeons generally run in suitable
bush-bearings, which should be well lubricated. Band conveyors should be
driven on the delivery and not the receiving terminal, as the tight side
of the band is the flattest. The guide rollers, for ordinary grain
conveyors, are fitted to the upper or working side of the band at
intervals of about 6 ft., and at distances of 12 ft. on the lower or
return strand. In cases where both strands of the band are used for
carrying grain, the lower strand must be supported by as many rollers as
the upper. Under such conditions, terminal pulleys must be of larger
diameter than usual, the object being to throw the two strands farther
apart, so as to give sufficient space between the two strands to spout
the feed in and out again at the other end. The two strands can be run
any distance apart by the use of two additional pulleys for the
terminals. This arrangement would be in place where it was desired, as
it might be, to run one strand of the band along the top floor of the
granary to distribute, while the other strand travelled along the
ground-floor or basement to withdraw, the grain.

[Illustration: FIG. 6.--Throw-off Carriage for Band Conveyor.]

Band conveyors are kept tight, when the band is not very long, by a
tightening gear, similar to that used on elevators, and consisting of
two screws which push or better pull the two pedestals of one terminal
pulley farther away from the other terminal. If the band is of such
length that an adjustment of 4 to 5 ft. on the tightening gear is not
sufficient, it is advisable to use in place of screws a tightening
pulley, over which the belt passes, but which is itself held in
tension by weights. The choice of the exact tightening gear will
depend on various considerations, the length of the belt, the type of
throw-off carriage used, and the quality of the belt all being factors
to be considered. The throw-off carriage (fig. 6), which serves to
withdraw material from the band at any desired point, is a simple but
ingenious appliance consisting essentially of guide pulleys which by
raising one part of the band and lowering the other have the effect of
causing the grain to quit the surface of the band at the point where
it is deflected upwards. The grain is thus cast clear of the band, and
into the air, being caught as it falls in a hopper and spouted in any
desired direction. Throw-off carriages differ in certai