Abstract: To determine the angular position of a rotating shaft starting from a standstill and going up to the highest permissible nominal speed and to suppress noise pluses in the square pulse sequence curve precisely corresponding to the tooth flank positions, a magnetic flux density signal received by a Hall cell (1) is compared with a threshold value signal (DC-TH)) in a standstill output unit (2) and a standstill output signal (AS") is produced. In addition, the magnetic flux density curve recorded by the first Hall cell (1) is compared with the magnetic flux density curve recorded by another Hall cell (1) and from that a window signal unit (5) generates a window signal (5) consisting of a sequence of pulses having a period that is approximately equal to a square pulse length. A static output signal (AS') is produced from the falling flank of the first pulse and the falling flanks of the subsequent pulses.

Abstract: The device proposed comprises a Hall sensor (101) with an associated magnet (102), a pulse-generation wheel (104) rotating at an angular speed w and fitted with teeth having a rising and falling face, the wheel turning in front of the sensor to generate a curve which corresponds exactly to the tooth-face positions and which can be used to determine precisely the position of the rotating shaft. The Hall sensor 9101) registers the variation with time of the magnetic flux density through the pulse-generation wheel (104) as a Hall voltage signal. This signal is converted by a differentiator circuit (103.2) into a differentiated signal. The maxima and minima of the differentiated signal are determined and a digital output signal (AS) is generated form the differentiated signal, the low-level to high-level transitions in the output signal corresponding to the maxima of the differentiated signal and the high-level to low-level transitions corresponding to the minima.

Abstract: Coke oven chamber doors form heat-resistant plugs having a construction to prevent damage when the plugs are removed and replaced. Each plug consists of an external door-body plate and internal steel plates. The ends of the internal plates overlap each other for relative movement. The lowermost plate is secured at its lower end and the uppermost plate is secured at its upper end. This provides a specific longitudinal dimension of the overlapping plates.