Throughout the 1960s, hydraulic excavators had gradually been gaining ground over their cable-operated counterparts. They were not only branching out into new industries with new applications, but also gaining in size. With excavators in Europe already entering the 10-cubic-yard class, Warner & Swasey took the plunge in 1972 and introduced America's largest to date, the Hopto 1900.
The giant excavator tipped the scales at 103 tons and carried a standard bucket of 5 cubic yards heaped capacity. A pair of GM 8V-71 diesel engines totaling 616 horsepower drove four gear-type pumps delivering 296 gpm into the hydraulic system, which operated at 2,750 psi. The 1900 backhoe boasted a digging depth of 35 feet 7 inches, and at ground level had a reach of 48 feet 10 inches. When handling pipe on a deep sewer job, it could lift 58,900 pounds at a 15-foot radius.
But the most striking feature of this giant excavator was its massive tractor-type undercarriage with a driving sprocket at both ends of each crawler assembly. While some prominent manufacturers of the day were still propelling their hydraulic excavators from the upper works through a center shaft and chain drive to the crawler sprockets, Warner & Swasey went somewhat "overboard" with their design.
Each sprocket was driven by a pair of hydraulic motors in the undercarriage for a total of eight motors, and each drive train incorporated a triple set of spur gears, plus a planetary final drive in each sprocket hub, for a total of 48 gears. Two-speed travel for this huge excavator was possible through a selector valve. When low speed was selected, oil was routed through all eight propel motors for maximum power. When high speed was selected, the same volume of oil was routed to the motors at only one end of the crawler, idling the motors at the opposite end and providing maximum speed. The advanced design included an automatic track-tensioning device operated by a hydraulic cylinder in each side crawler frame. Single-grouser or flat shoes were available.
The Hopto 1900 possessed an impressive heritage, descending from one of America's earliest hydraulic excavators. The Badger Machine Co., incorporated in 1946, developed a tractor-mounted hydraulic backhoe and called it the "Hopto" (Hydraulically-Operated Power Take-Off) because it was driven by the tractor's power take-off. From 1958 to 1977, Badger was owned by Warner & Swasey, which developed the Hopto idea into a line of crawler, wheel and truck-mounted hydraulic excavators. After 1977, the Hopto machines were made by Badger Construction Equipment at their factory in Winona, Minn. The 1900 enjoyed a lengthy production run, latterly as the Badger Hopto 1900. The last one was shipped in 1990.
You can read more about the evolution of construction equipment in Keith Haddock's latest book release, an updated version of his fully illustrated Earthmover Encyclopedia now in bookstores. Also, consider a membership in the Historical Construction Equipment Association, www.hcea.net .