Frame articulation is a standard feature on wheel loaders today, but it was not always the case.
Mixermobile of Portland, Ore., introduced the first articulated loader as early as 1953, but the concept was slow to catch on. It took another decade before the leading loader manufacturers recognized articulation as the way to increase loader productivity through better maneuverability and shorter cycle times, and began introducing them into their lines.
In 1959, the Hough Division of International Harvester began work on a prototype articulated machine that would become a milestone in the company's history. Known as the D-500 Paydozer, its design followed market analysis with customers and distributors who indicated the need for a large rubber-tired dozer for pushloading scrapers and stockpile handling. Articulated steering was chosen over rigid-frame rear-wheel steering because it permitted a shorter turning radius and the ability to "walk out" of soft spots.
When International officially launched the D-500 in 1961, it was claimed to be the first articulated wheel dozer, and the largest machine International had built to date. Powered by a 600-hp Cummins engine, it tipped the scales at 145,000 pounds. Blade width was 13 feet 3 inches, and overall machine length totaled 29 feet.
With the basic design of the D-500 proven in the field, the next logical step was to design a loader version of the large articulated rubber-tired dozer. This appeared in 1964 in the form of the H-400 Payloader. Developed from the D-500 dozer, it was not only International's first loader to feature an articulated frame, but it was also the largest the company had built up to that time. Carrying a standard bucket of 10 cubic yards, it was also one of the largest available on the market. Optional power was either Cummins or GM V12 diesel engines developing 420 flywheel horsepower, slightly less than the D-500. Operating weight was 113,000 pounds. Operator surveys favored the cab's location on the front section of the machine, so that location was adopted by International for all its subsequent loaders.
With the stage set for further articulated loaders and dozers, International followed the industry trend by eventually replacing all of its former rigid-frame machines with articulated models based on the original D-500 design. The H-400 graduated into the H-400B in 1969 with 500-flywheel horsepower. Then the 580-hp H-400C took over in 1973 and lasted until 1980. Meanwhile, the machine that spawned International's entire articulated loader line, the D-500 Paydozer, enjoyed a production life of some 12 years ending in 1973.
In 1982, Dresser Industries acquired International Harvester's Payline Division and the tradename Dresser was adopted. Another change occurred in 1988 when Japan's Komatsu and Dresser Industries began the Komatsu Dresser Co. joint venture to market both companies' lines.
You can read more about the evolution of construction equipment in Keith Haddock's illustrated book "The Earthmover Encyclopedia" available in most book stores. Also, consider a membership in the Historical Construction Equipment Association, www.hcea.net.