The 78 Series single-conductor stringing blocks are an ideal choice for stringing large-diameter transmission-class conductor. These blocks are available with 20″, 22″, 28″, 35”, and 42″ (OD) sheaves, and they are light-weight, yet exceptionally rugged, reliable, and durable. Their low-friction bearings render high block efficiency, which helps to maximize stringing distances while minimizing pulling tensions and reducing loads on stringing equipment. Combined with the associated family of hardware and accessories, the 78 Series affords utilities and their contractors exceptional versatility in how and where it may be deployed and in the range of installation problems it can help solve.

The 78 Series blocks’ light weight and durability derive from the materials and methods used to make them. The material used for the frame is “virgin” A356-T6 Aluminum, which is an aluminum alloy with very tightly controlled proportions of other materials to assure optimum performance during manufacture and in the field. Virgin material is material that has not been mixed with scrap material, not even with scrap of what may have once been the same alloy. That Sherman & Reilly uses “virgin” material assures that the material is exactly and only the pure and correct alloy, and that it has not been contaminated by impurities (notably iron) that often accompany non-virgin material.

78 Series frames are cast (molded) as molten metal. The properties and purity of the A356-T6 Aluminum used by Sherman & Reilly assure that the molten metal flows smoothly and evenly throughout the mold, assuring proper and uniform density throughout the finished frame. Proper density and uniformity combined with the purity and metallic properties of the alloy assure that the frame is strong but light-weight, and assure that there are no internal voids or brittleness that could cause sudden complete failure of the block in the field.

The sheaves of the 78 Series are also made of the same virgin A356-T6 Aluminum as the frame. They are also similarly cast, but they have the additional manufacturing step of having the grooves and bearing surfaces machined for smoothness and precision fit. Combined with low-friction, lubricated-for-life bearings, the sheave materials and how they are made assure high-efficiency and smooth-stringing performance.