BALATA BELTING This belting employs balata, a gum obtained from the bullet tree (Mimusops balata), which is a native of Guiana and the West Indies. Balata is related to gutta-percha, the latex contain ing a high proportion of that substance. Its advantages for the purpose of belting are non-elasticity, great power of penetration when in solution (so that the fabric used as a base can be rendered thoroughly waterproof and solid), and tenacity in binding the plies. It offers great resistance to oxidation.
The basis of the balata belt is cotton-duck, necessarily of high grade, for its fibres must withstand the strains of transmission, and be of such evenness of quality and texture that the belt through out its length and width is of uniform strength and suppleness to ensure true running. American cotton of long staple gives the best results. For the requirements of belting the duck must be both tightly spun and woven. The relation of the strength of the weft to the warp is of considerable importance, for although all the tension in a belt would appear to bear on the warp, yet this must be strengthened and supported by the weft, or the belt will lose its shape, pull narrow and stretch.
The duck is thoroughly impregnated with a carefully cleaned solution of balata. This operation is most important, for the duck must be thoroughly saturated before being made up into belts. After evaporation of the solvent agent, the treated duck is ready for translation into various widths and plies. It is therefore heated to reduce the balata to a partially melted state, and in this con dition the duck is folded in the number of plies required under heavy pressure. The belt is then passed through very heavy rollers, and severe tension applied by way of tests. The result is a belt of great tensile strength and true running. An ingenious manufacturer has designed a belt which combines balata with leather. The upper part of the belt is of balata based on cotton duck as here described ; beneath it are transverse strips of oak tanned leather attached to the balata by strong metal rivets so well sunk into the leather that they do not touch the pulleys. The balata takes the pull, and the leather strips which are attached to it give grip.