Process and Basic Industries

A typical application for the speed sensors from Lenord + Bauer can be found in forestry machines from a leading Finnish manufacturer. The machines, known as harvesters, fell and process trees using the cut-to-length method. The harvester head grips the trunk at its base, fells the tree then draws the trunk past integrated blades to de-branch it. As the trunk returns though the harvester head it is cut it to the lengths required for later use. This method offers a high productivity by reducing the handling and facilitating the mobility of the machines as well as enabling a documentation of the wood volume processed.

For the correct length measurement despite frequent back and forth movement of the trunk, direction detection is necessary. Due to the compact design of the harvester head, space for a measuring system is restricted.  The speed sensor GEL 248 from Lenord + Bauer provides the solution. Approximately the size of a walnut the speed sensor detects a rotating toothed target wheel attached directly to a roller which runs on the trunks.

The speed sensor contains two pre-set sensors in one housing which provide two incremental outputs phase shifted by 90º allowing for length and direction evaluation in the control electronics. The flange mounting enables a simple and fast installation with practically no adjustment necessary. The speed sensor are ideally suited for coping with the harsh environment in a forest with uneven or non-existing tracks and changing climatic conditions.

The contact-less magnetic measuring system together with the electronic circuitry are full potted in a metal housing. They are therefore shock and vibration proof and are not affected by moisture, dirt or oily grime. The reliability of the speed sensor used in harvesters in forest locations where the nearest workshop is a long way off can well be appreciated. 

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