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?