Abstract: Method for cleaning an exhaust gas or a process gas of a manufacturing process of semiconductor components, whereas the exhaust gas or process gas comprises at least one hydrogen chalcogen compound comprising at least one of the following: a) sulfur (S); b) selenium (Se); c) tellurium (Te); and d) polonium (Po), wherein said hydrogen chalcogen compounds are removed in a wet scrubber from the process gas by guiding the process gas into an aqueous solution of at least one base; supplying the least one base to the aqueous solution and extracting an output exhaust gas stream from the aqueous solution, characterized in that the amount of base supplied is controlled such that the pH-value of the solution is larger than 12. The apparatus (1) and the method according to the present invention allow the efficient removal of hydrogen chalcogen compounds from exhaust gases of the production processes of semiconductor compounds like e. g. photovoltaic modules.

Abstract: A method and apparatus for braking a revolvable superstructure of a working machine by counter-steering. A working machine has a superstructure which is driven by a motor via a transmission. A control lever operates a control valve which sends signals to a pivoting pump. The control lever has at least one neutral position and at least two switching positions. When the control lever is moved to a braking position, a switching logic circuit coupled to the pivoting pump is actuated and reverses the pivoting pump. This reverses the direction of revolution of the superstructure and brakes the revolution of the superstructure by counter-steering. A monitoring device coupled to the switching logic circuit monitors the number of revolutions of the superstructure. The braking is stopped when the monitoring device detects that the superstructure has come to a standstill.