Abstract: The twin pusher centrifuge contains a sieve or filter drum having discharge openings at both of its ends. At the center of the sieve or filter drum there is arranged an inclined pusher or thrust floor member. This pusher floor member rotates at a rotational speed differing from the rotational speed of the sieve or filter drum. Consequently, the pusher floor member performs a wobbling or wobble movement between two extreme positions. Due to the wobbling or wobble movement the centrifuged product is pushed towards the two ends of the sieve or filter drum. The product infeed opens within a central aperture formed in the pusher floor member, whereby the product is uniformly infed on both sides of the pusher floor member. The product infeed occurs either in a continuous or periodic fashion. In this manner an energy-saving jerk-free operation of the centrifuge is achieved using a particularly simple construction.

Abstract: The twin pusher centrifuge comprises a sieve or filter drum having discharge openings on both sides thereof. At the center of the sieve or filter drum there is provided a pusher rotating at a rotational speed which differs from the rotational speed of the sieve or filter drum. The pusher contains pushing surfaces which are inclined at an angle relative to the direction of product movement. Product infeed pipes open to the rear of the pushing surfaces. These pushing surfaces are alternatingly positioned at opposite inclinations or comprise two pushing surfaces directed at opposite inclinations with respect to one another. Due to such an arrangement the product which is infed to the center of the sieve or filter drum is pushed from such center or central region of the drum towards both sides thereof in the direction of the discharge openings. An energy-saving and jerk-free operation of the centrifuge is thus obtained while employing a particularly simple construction of centrifuge.

Abstract: A radiation detector for simultaneously detecting electromagnetic radiation from a number of separate receiving regions by means of a single radiation receiver. Optical bundling means are arranged such that they direct the radiation emanating from the individual receiving regions onto the single radiation receiver. The optical bundling means comprise surfaces having two different main radii of curvature. The radiation receiver is arranged at the one main focal point of the individual surfaces.

Abstract: To eliminate sources of error in fire detection apparatus regarding variation of light output from a radiation cell, and to eliminate varying ambient conditions such as dust and dirt contamination of reflectors and transducers, the radiation is directed over at least two paths by reflectors which are located such that the numbers of reflections in the paths and the reflection points are the same, whereas the lengths of the paths are different, and evaluating the difference signal to obtain a measure of the density of the medium through which the paths extend, typically the transmissivity of air which may be contaminated by smoke. In one embodiment, reflectors are located in the corners of a polygon, one of the paths extending across the polygon, and the other path extending essentially circumferentially thereof.