Marginal Column

Moving masses

Hydraulics from Rexroth have been moving the world for sixty years.

Photo | Bosch Rexroth AG

The range of hydraulic products back in 1953.

Back in 1953, several German enterprises independently set about making a name in the sector for fluid hydraulics. Rexroth’s iron foundry in Lohr presented its first hydraulic valves, Bosch started up in Stuttgart with an external gear pump for farm tractors, Hydromatik of Ulm began designing high-pressure pumps, and Brueninghaus of Werdohl was about to build its axial piston manufacturing plant. Today, some 60 years later, these companies have pooled their hydraulics competence as Bosch Rexroth.

The professional world was impressed by the cylinders and valves and by the high bursting strength of Lohr’s castings. This was why, in 1956, Rexroth landed an order to equip Europe’s first fully hydraulic steel mill in Völklingen an der Saar. Bosch pressed ahead with mechanizing agricultural equipment, using its gear pumps. Technical advances such as double radial compensation increased efficiency to ninety percent within a single decade – making the final breakthrough for mobile hydraulics in agricultural technology. At the beginning of the 1960s, it was the first company to introduce valve manifolds and high-pressure hydraulics. This was the basis for later securing a dominant position in the large excavator industry.

As early as the mid-1960s, industry was calling for control valves with which pressure and flow volume could be set flexibly. In response, Rexroth developed the electronics for a hydraulic winder drive in 1966. Electro-hydraulics was born and its triumphant success spread throughout the entire industrial machine tools sector. Sensors, amplifiers and actuators assumed more and more functions in hydraulic equipment. In 1979, Rexroth presented the first AC servomotor suitable for industrial applications and free of maintenance requirements.

Eight years later, with the whole world watching, 212 CNC controlled hydraulic cylinders proved their precision capabilities. In the Norwegian Ekofisk oil field they lifted five offshore oil platforms that had subsided by six meters – with a deviation of only three millimeters from constant velocity.

Although in 1997 Rexroth hydraulics were driving an 800-ton power shovel in a Canadian open-face oil shale mine, the company’s engineers were focusing their attention on how to make units smaller and while improving their performance. To achieve this, it became increasingly important to create a responsive and closely controlled interaction between diesel engine management, working hydraulics, traction drive, and auxiliary units.

During the 1990s, user-programmable axis controls were able to interface with a field bus while intelligent control functions were integrated into valves and pumps. Recent years have been dominated by energy conservation, digitization and system-based solutions. Diesel Hydraulic Control coordinates the traction drive with working functions. The Hydraulic Fly Wheel stores energy during phases when it is not needed and makes it available again as required. Efficient technologies like these are among the advances that today make diesel-powered machinery able to fulfill statutory emission standards that are becoming ever stricter. In the field of industrial equipment, the Sytronix variable-speed pump drive supports the trend towards efficient solutions using motor-regulated drive systems and opens up huge energy saving potentials. In the future, intelligent controls, motor-regulated drives, and holistic system approaches will continue to be the most important innovation drivers in the field of hydraulics.