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PI 030-17 Lohr am Main, 2017-06-09

High-performance winches in the upper machinery: Mechanical load often underestimated

Load Limiter: Autonomic, hydraulic unit reduces abrupt loads to values below the standard specification.

Mobile measuring device shows actual force developments in case of emergency stop – retrofitting often necessary and possible

Current measurements at installed upper machinery drives prove that in case of a category 0 emergency stops, the load on the mechanics is much higher than previously assumed. In reality, the design criterion of twice the rated load prescribed by DIN 56950-1:2012-05 is often critically exceeded by the simple accident load. This may result in considerable risks for human beings working under the hovering loads. Using a new mobile measuring device, stage operators are now able to measure the actual loads and to economically retrofit the high-performance winches that are affected.

Rexroth has systematically measured the real force developments which act on the structures in case of a hard emergency stop in extensive tests on test stands and in two theaters. In case of a category zero emergency stop, the real values exceed two times the rated load by up to 75 percent. The usual design limit of two times the rated load for installed winches was already exceeded from half the rated velocity; and the exceedance was so clear that for safety reasons, the engineers refrained from completing tests at full velocity. Not visible from the outside, the high loads may cause structural changes in the construction and finally a load crash due to an abrupt brittle fracture.

Mobile measuring device reveals need for action

The measurements were completed using Rexroth’s newly developed, mobile measuring device Stage Guard. The heart of this device is a highly sensitive acceleration sensor providing for wireless transmission of the test values. Based on these values, validated software calculates the influencing factors force, velocity, path and impact. If the measurements show that the real loads are clearly larger than the calculated and documented ones, stage operators are obliged to react. They must either extensively adjust the mechanical design to the actual loads, retrofit the winches or reduce the admissible velocities and loads according to the measurement results.

In this connection, Rexroth offers two possibilities: The autonomic, hydraulic Load Limiter damping unit ensures that in case of emergency stop, two times the rated load and the maximum acceleration of 2g will not be exceeded at any time. With hydraulically driven winches, operators can replace the usually used passive logic circuits by new valves with active logics. In this connection, adjustable braking ramps provide for considerably softer deceleration. They prevent abrupt loads in case of emergency stop and thus protect the mechanics.

Economical, precise, safe, and energy efficient: drive and control technology from Bosch Rexroth moves machines and systems of any size. The company bundles global application experience in the market segments of Mobile Applications, Machinery Applications and Engineering, and Factory Automation to develop innovative components as well as tailored system solutions and services. Bosch Rexroth offers its customers hydraulics, electric drives and controls, gear technology, and linear motion and assembly technology all from one source. With locations in over 80 countries, more than 29,500 associates generated sales revenue of approximately 5 billion euros in 2016.

To learn more, please visit www.boschrexroth.com

The Bosch Group is a leading global supplier of technology and services. It employs roughly 390,000 associates worldwide (as of December 31, 2016). The company generated sales of 73.1 billion euros in 2016. Its operations are divided into four business sectors: Mobility Solutions, Industrial Technology, Consumer Goods, and Energy and Building Technology. As a leading IoT company, Bosch offers innovative solutions for smart homes, smart cities, connected mobility, and connected manufacturing. It uses its expertise in sensor technology, software, and services, as well as its own IoT cloud, to offer its customers connected, cross-domain solutions from a single source. The Bosch Group’s strategic objective is to deliver innovations for a connected life. Bosch improves quality of life worldwide with products and services that are innovative and spark enthusiasm. In short, Bosch creates technology that is “Invented for life.” The Bosch Group comprises Robert Bosch GmbH and its roughly 440 subsidiaries and regional companies in some 60 countries. Including sales and service partners, Bosch’s global manufacturing and sales network covers nearly every country in the world. The basis for the company’s future growth is its innovative strength. At 120 locations across the globe, Bosch employs some 59,000 associates in research and development.

Additional information is available online at www.bosch.com , www.iot.bosch.com , www.bosch-press.com , www.twitter.com/BoschPresse .

 

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Contact

Susanne Herzlieb
Maria-Theresien-Straße 23
97816 Lohr am Main
Phone: +49 9352 18-1573
susanne.herzlieb@boschrexroth.de




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