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No-Bearing Encoders for Large-Diameter Shafts

March 15, 2012
Slim designs resist shock and transmit without interference
A MAG-G magnetic encoder with a split pulse wheel and scanning head.

The new MAG(-G) 50-1200 magnetic encoders from Johannes Huebner GmbH can be installed without bearings or housings, and the system is designed to be resistant to shocks and vibration. It also transmits interference-free signals even under extreme conditions. The developer said the new technology adds an alternative to the standard optical scanning principle, which has to be protected in a closed housing with a bearing-supported shaft.

The magnetic scanning principle developed by Johannes Huebner uses a stationary sensor that records magnetic field changes of a rotating pulse wheel with north-south poles. The alternating magnetic field produces a sinusoidal or rectangular voltage in this sensor, and the magnetic scanning principle boasts additional benefits: It is resistant to soiling and provides for large radial and axial tolerances.

Huebner noted that its magnetic encoders are wear-free and low-noise devices. The variant with a split pulse wheel is particularly well suited for retrofits and upgrades, as well as for applications without a free shaft end. Magnetic encoder technology effective in numerous industrial applications, including in steel mills, ship drives, gas and water turbines, pumped storage power stations, large excavators, conveyors, and drilling rigs, among others. Adjustments can be made to meet the individual customer’s requirements, the developer noted.

The Huebner magnetic encoders can be installed in highly confined spaces due to their narrow design. For shaft diameters between 16 mm and 1,000 mm, the system adapts flexibly to the specific set-up of the customer’s application. Various options are available for attaching the pulse wheel, depending on the actual design conditions, including screw mounting and hot shrink fitting as well as mounting by means of clamping pieces, clamping plates, or tolerance sleeves.

The developer further noted its magnetic encoder systems can output various types of electrical signals: sinusoidal, incremental and absolute signals (SSI, EtherCat, other bus interfaces.)

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