With increasing competition from European hydraulic-excavator producers in the early 1960s, traditional American manufacturers of cable-operated excavators struggled to change over to the new method of digging. Increasingly reliable hydraulic machines were more maneuverable, easier to operate, cheaper to buy, and offered positive bucket action in all directions. Many long-established excavator builders could not make the change and consequently discontinued their product or merged with other companies. Others made a brave attempt at designing their own machines with mixed success. Leading excavator builder Bucyrus-Erie fared better than most by recognizing the hydraulic advantage at an early date.
Bucyrus-Erie made its first move into hydraulic machines by purchasing Milwaukee Hydraulics in 1948, a company that two years earlier had introduced one of the world's first hydraulic cranes. The result was a line of truck-mounted hydraulic cranes and excavators known as the Hydrocrane and Hydrohoe. Although these early machines did not impact sales of the company's cable excavators, they laid the foundations and provided experience for the company to launch a new line of crawler-mounted, fully revolving excavators in the 1960s.
In 1965 Bucyrus-Erie unveiled the 20-H, first of a new range of crawler-mounted excavators that would eventually cover sizes up to the 60-ton 40-H. The 3/4-yard 20-H was powered by Cummins or GM diesel engines of 106 horsepower, and weighed 19 tons in operation. The modern-looking machine featured a low-profile engine house, isolated operator's cab, and a ball bearing swing circle. But showing its cable-excavator roots, the hydraulic propel motor was mounted in the upper works with drive to the crawlers transmitted through the center pintle via shafts and gears, and steering actuated by air-operated jaw clutches and brakes. The final drive to the heavy-duty crawler-crane undercarriage utilized tumblers rather than sprockets as in later models.
Keeping pace with European competition, Bucyrus-Erie broadened its hydraulic-excavator line by introducing the 1/2-yard 15-H in 1966, the 1-3/4-yard 30-H in 1967, and the 3-yard 40-H in 1970. By the time the 40-H appeared in 1970, the outmoded form of propel with motor in the upper works and air-operated clutch steering had been replaced by a hydraulic motor in each crawler side frame, providing independent drive to each crawler. Independent crawler drive was also provided in later upgrades to the 15-H and 20-H.
Further advances appeared in 1975 when Bucyrus-Erie introduced the 350-H, a 46-ton backhoe of 2-1/2 yards capacity and forerunner of a new line of state-of-the-art excavators with high-pressure variable-displacement piston pumps. This efficient system, used by European manufacturers since the 1950s, departed from the fixed-displacement low pressure gear type motors employed in most early American designs. By the end of the decade, this new line had superseded all previous models and was topped by the 112-ton 500-H at 5 cubic yards capacity. In 1985 Bucyrus-Erie sold its entire construction-equipment business to concen-trate on its larger machines for the surface mining industry.
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Learn more about machines of Bucyrus-Erie and Bucyrus International in Keith Haddock's new, fully illustrated book: “Bucyrus Construction and Mining Machines 1880 to 2008” available in most bookstores. Also, consider a membership in the Historical Construction Equipment Association, www.hcea.net And be sure to visit ConstructionEquipment.com for past Iron Works features.