A seam of brown coal can be as deep as 100 m below the surface of the earth. In the majority of cases bucket wheel excavators are used to recover the coal. The so-called stone excavation masks a high risk. The bucket wheel can become blocked if a tooth of a bucket comes up against a pocket of firmly entrenched stone. The increased load moment can result in the speed of the bucket wheel dropping within a very short period of time. At the same time the blockage causes the bagger wheel boom to lower. The entire construction of the bucket wheel excavator performs a dipping motion in the opposite direction to the rotary movement of the bucket wheel. This results in a further drop in the rotary speed of the bucket wheel. Personnel could be exposed to a hazardous situation if the tooth of the bucket wheel slips from the stone and causes the bucket wheel boom to swing upwards.
Bucket wheel excavator stone recognition
The high-resolution incremental encoder FG(H) 40 is equipped with a pulse disk and optical scanning technology to provide up to 1 million pulses per rotation. Utilizing this encoder ensures it is possible to halt the bucket wheel within a rotational movement of less than 2° should the speed of the bucket wheel drop by just 0.5 rpm – before damage can occur to the power train. As is the case with all Hübner devices the FG(H) 40 is designed for use in heavy duty applications. Suitable for temperatures ranging from -25 °C to +85 °C it is also highly resistant to shock and vibration. Standard degrees of protection to IP66 and IP67 ensure they can be used in both wet and dust-laden environments. Above all, the new FG(H) 40 encoder and considerably faster reaction time for stone recognition improves the safety of excavator personnel.