Do not tax belts by overloading. Keep them free from accumulation of
dust, grease and all animal oils, as these are injurious to both rubber
and leather belts.
Special care should be taken to protect the edges of rubber belts from
all animal oils, as they are liable to rot the belt.
Always run the grain (or hair) side of leather belts on the pulley, as
it gives greater driving power, hugs the pulley closer, is less liable
to slip, and will drive 30 per cent. more than the flesh side.
Rubber belts will be greatly improved and their life prolonged, by
putting on with a brush, and letting it dry, the following mixture:
Equal parts of black lead and litharge mixed with boiled oil; add
enough Japan to dry it quickly. In case the rubber peels off, the same
mixture can be used.
In comparison to leather belts, 4-ply rubber is equivalent to a single
leather belt and 6-ply rubber to double leather belt.
=To find the length of a belt=, add the diameter of the two pulleys
together, divide the result by 2 and multiply the quotient by 3¹/₇;
then add to this product twice the distance between the centers of
shafts.
=When piecing a belt when pulleys are changed=, multiply the difference
of the diameters of the pulleys by 1½, the product will be the length
of the piece required.
The seam side of rubber belt should always be placed outside and not
next to pulley. In case the belt slips, coat the side next to pulley
with boiled linseed oil or soap.
=In lacing a belt=, begin in the center and be careful to keep both
ends exactly in line. Lace both ends equally tight and do not cross
the lace on the pulley side of belt. Great care should be taken that
the ends butting together be cut perfectly square; if not, the belt
will stretch more on one side than the other, which greatly impairs its
worth.
Q. What is the practical limit of belt speed?
A. Belts should not be run much over 5000 feet per minute.
Q. How then is the capacity of a belt affected by its speed?
A. It varies directly as the speed. A given belt will transmit twice
the horse-power if its speed is doubled within limits.
Q. Is the capacity of a belt affected by its width?
A. Yes, the capacity varies directly as the width. If a two inch belt
will transmit one horse-power, two such belts will transmit two horse
power; and this is true whether they are run separately or joined into
a four inch belt.
To preserve cotton or Gandy belting, apply with a brush a little common
paint to pulley side of belt while running, to be followed shortly
afterwards by a little soft oil or grease to preserve its flexibility.
If the edges of the belt become frayed from the use of belt guides or
forks, the loose threads may be cut off without injury to the belt.
If the belt slips at first, consequent to the surface being ruffled by
unrolling, apply a little grease, oil or soap to the pulley side to
make it grip.
[Illustration: Armington & Sims High Speed Engine.]