Transmission Blocks – 74 Series

Transmission-class line construction is very specialized. Structures are taller, spans are longer, conductors are larger/heavier/stiffer, and pulls are longer and can extend over steep and very uneven terrain. In addition, aluminum conductors vary in construction requirements, calling for
special handling techniques, tools, and equipment.

Transmission construction also involves different line and structure designs, as well as different
conductor configurations. Some lines are strung using conventional, ground-based equipment
and tools, while others require stringing using helicopters.

The configuration and quality of the blocks in which sheaves are mounted are as important as
the sheaves.

About 74 Series Transmission Blocks
The 74 Series single-conductor stringing blocks are an ideal choice for stringing large-diameter
transmission-class conductor. These blocks are available with 10″, 12″, 14″, and 16″ (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 74 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 74 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.

74 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 74 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.

Specifications:

• 10 in, 12 in., 14 in., and 16 in. sheaves
• Conductor guard to minimize risk of lines binding between sheave & frame.
• Available as polished-groove or lined with neoprene or urethane.
• High-strength Aluminum-alloy frames and sheaves.
• High-efficiency bearings, with provision for pressure-lubrication.
• Forever Warranty™