Marginal Column

Discovering the quiet

Noise harms both humans and nature. But for many years it was felt to be an acceptable by-product of progress. Not true at Bosch Rexroth. The company invested in developing low-noise technologies quite early on and, down to the present day, makes a contribution to living and working in quieter surroundings.

Photo | Bosch Rexroth AG

In 1972 Rexroth started combating noise right at its source. Shown here is an employee using an audiometer. At the right is a noise measurement chamber.

The noise in the “Hammer from Hell” – the trip hammer forge put into service by the Rexroth family in 1795 – must have been ear-splitting. The hammer, lifted by a waterwheel, repeatedly dropped its full weight on the workpiece. This example nonetheless stems from a period in the early history of the company, when things were still relatively quiet. As industrialization progressed, the world got louder. The pounding of machines, the roar and hiss of the railroad, and the scream of factory whistles characterized the acoustic background, even at Rexroth. Right at the beginning of the 20th century, famed physician Robert Koch warned of the health implications associated with ongoing exposure to noise. “One day people will have to combat noise just as relentlessly as cholera and the plague.”

But at that time, noise still stood for power, strength and progress – and was thus tolerated. Only in 1974 was the Federal Anti-Pollution Act passed in Germany, seeking to curb the increasing stress that noise exerted on people and the environment. By that time, however, the topic had already taken root at Rexroth. As early as 1971 the company introduced its “Whisper Pump”, a low-noise, variable-cell pump. Massive amounts of work and money have been invested since then in special acoustic measurement chambers and noise laboratories – and in developing new products.

In the mid-1970s, low-noise axial piston pumps and hydraulic power units were marketed. With noise-absorbing hoods for pump units, low-noise container con struction, and sliding bearings for units with inclined axes, the developers attained further progress. Things became quieter all around: at the work site, on streets and roads, and even on the theatrical stage. In many areas Rexroth and its products continue to contribute to a quieter environment.

That is an achievement for which the company recently earned great praise – twice, in fact. In 2011 the famed INDUSTRIEPREIS was awarded for the SILENCE PLUS external gear pump. Its noise level is, on average, 15 decibels lower than for the conventional pump. The pump’s sound, lower in pitch and more pleasant, also convinced the jury for the John Connel Awards, which awarded the “Noise Oscar” to the same innovative product in the same year.