After taking on the Pewag Grade 120 profile chains and components three years ago, Randy Gray, parts manager for Construction and Aggregate Products Inc., a lifting gear distributor in Des Moines, Iowa, has seen the product line flourish in industries where tradition takes precedence over technology.
According to Gray, industries such as railroad construction, which relies heavily on traditional methods of lifting, often use cumbersome products that are difficult to work with. Despite the industry's history of using dated construction techniques • some methods like using cables and straps for heavy lifting have been used since the 1800s, Gray says • crane owners who lift ties and trusses to build railroad bridges have been accepting of Pewag's Grade 120 chains for a number of reasons.
For one, Grade 120 is stronger and lighter than other chain grades. It offers a 50-percent increase in working load limit over Grade 80, which leads to a reduction in chain size. For a load weighing 4,500 pounds, the recommended Grade 80 chain size is 5/16 inch, while the recommended Grade 120 chain size is 9/32 inch. Similarly for a load weighing 10,600 pounds, the appropriate Grade 80 chain size is 1/2 inch while Grade 120 would only need to be 3/8 inch. On the other hand, if the same size Grade 80 and Grade 120 chains are used, then the Grade 120's capacity is increased.
Chain downsizing also results in a lower overall weight. For example, a 5-foot-long Grade 80 chain sling handling 5,200 pounds weighs 24.59 pounds. A 5-foot-long Grade 120 chain sling lifting the same load weighs only 14.56 pounds • a 40-percent weight reduction.
The shape of Pewag's Grade 120 chain also provides lifting improvements. Because of the profile shape of the link, the interior of Grade 120 has one-third more surface area than round Grade 100, Gray says. Additionally, due to the special form of the profile chain, larger contact is achieved between the bearing surfaces of the links, which reduces the surface pressure on the chain and, consequently, reduces wear.
Another feature of the Grade 120 chain is that it has a 38-percent higher moment of resistance when compared to regular round-link chains with the same diameter, which allows it to withstand bending forces better than round-link chains and makes it well-equipped for heavy applications. With the same dimension of chain and workload, the Grade 120 also offers a design factor of 6:1 when used at Grade 80 work loads with 4:1.
Back to railroad construction, Gray says cranes building railroad bridges would pick concrete trusses and put the concrete ties under switch plates that weighed 200,000 pounds. “The crane would pick 50 at a time using 100 chains,” he says. “We first supplied them with Grade 80 or Grade 100, and the chains would fail within four to five months.” However, since the company started supplying Grade 120 chains for railroad construction, he says there have been no chain failures.
Because the product is more expensive, Gray says he initially gave the chain to his customers at no cost to see if they liked it before buying. As a result of the Grade 120's benefits, he adds, “We've had no problem selling it.”
Gray's customers who stayed within the workload of the chain reported having fewer breakdowns. However, with fewer breakdowns, Construction and Aggregate Products isn't selling as many Grade 120 replacement chains as it had with other grades. The solution: Gray says the company is constantly seeking out other uses for Pewag's Grade 120 chains, including horizontal pulling.
Construction Aggregates has found that in the business of severe abrasive applications, such as cured concrete and new structure building, Grade 120 is holding up about two times longer than round Grade 100. Additionally, Gray says that Grade 120 has found a home in underground utility horizontal boring and drilling. With higher work loads, less chain breaks and the compact links not binding as easily as round link, Grade 120 uses less energy to pull, therefore, work is faster with greater production.