Belt Tension

—The ultimate strength of leather belts varies from 3,000 to 5,000 Ibs. per square inch. But at the laced joints the strength is only 30% of those values, or from 900 to 1500 Ibs. per square inch. The working tension should not exceed about 300 lbs. a square inch. A good rule is 20 lbs. per inch of width for each 7g inch in thickne of the belt. The tensile strain is found by multiplying the number of the H. P. to be transmitted by 33,000 and dividing the product by the velocity of the rim of the pulley in feet per minute. This represents the strain in pounds upon the driving side independently of the initial tension producing adhesion between the pulley and the belt. This initial tension should be sufficient in amount to prevent slipping on either of the pulleys at the moment of starting.