Advent of Articulation: Wheeled Loaders

Sept. 28, 2010


The LD-8A of 1961 boasted four-speed powershift transmission with torque converter, four-wheel planetary drive and air brakes on all wheels. It was powered by a Cummins 175-hp diesel engine and tipped the scales at 34,500 pounds. The loader was rated at 12,500 pounds carrying capacity with its standard 3½-yard bucket.

Wheeled loaders originated in the 1920s when small agricultural tractors were fitted with a loader bucket. Originally designed as a rehandling shovel for light materials, the loader gradually evolved from a tractor with an attachment to a heavier machine for earthmoving applications, built specifically as a loader. After World War II, established manufacturers began to produce wheel loaders in larger sizes, and several new manufacturers joined the competition.

A significant step in wheel loader development was the introduction of the articulated frame. Mixermobile Manufacturers of Portland, Ore., pioneered this concept in 1953 with the Scoopmobile Model LD-5. The Scoopmobile name goes back to 1939 when Mixermobile introduced a line of three-wheel rigid-frame loaders. As with so many other brilliant innovations, articulation was not fully appreciated at first, and it took several years before contractors realized that the additional cost of articulation gave them greater maneuverability and shorter cycle times for their loaders. It was not until the mid-1960s that all the leading equipment manufacturers included them in their lines.

The LD-5 weighed 12,900 pounds and carried a standard bucket of 1¼ cubic yards with 5,000 pounds load capacity. Power to all four wheels was provided through an exclusive flexible coupling, permitting the two axles to oscillate independently as well as providing articulation between the two frames. Scoopmobile rapidly added more LD-series models to its articulated loader line and, by the early 1960s, offered five basic sizes with many variations.

Mixermobile's crowning glory arrived in 1965 when the company unveiled its Scoopmobile Model 1200, taking the title of the world's largest wheel loader. The massive machine, in the 10-cubic-yard class, was offered with either a 525-hp Cummins or 475-hp GM diesel engine.

In 1968, the Scoopmobile line of loaders merged into the Construction Equipment Division of Westinghouse Air Brake and the machines sold under the Wabco name. The line diminished soon after that date and, in 1974, the manufacturing rights were purchased by the Eagle Crusher Co. of Galion, Ohio. They continued to build the machines in dwindling numbers until the last Scoopmobile left Eagle's works in 1989.

You can read more about the evolution of construction equipment in Keith Haddock's illustrated book "The Earthmover Encyclopedia," available in most bookstores. Also, consider a membership in the Historical Construction Equipment Association, .