Abstract: A muffler for pulsating gases, especially exhaust gases of internal combustion engines, comprises a housing into which an inlet conduit enters, from which at least on outlet conduit exits and which is divided by at least one partition wall into at least two chambers. In this muffler the flow cross section of a flow path connecting two chambers and/or of an outlet conduit can be varied by means of an adjustable closure element. An actuating element acting on the closure element is provided in the region of the exit cross section of the inlet conduit.

Abstract: A method and apparatus for the generation of elevator car position information in an elevator shaft includes a safety light barrier mounted on the car and actuating vanes in the shaft cooperating with a safety circuit for connecting the door and lock contacts to a source of electrical power in the door zone of a destination floor for a stopping elevator car. The safety light barrier has two transmitters and two receivers which are positioned on a horizontal line and are masked simultaneously by the actuating vanes. The safety circuit includes two redundant systems for signal preparation and signal evaluation including test circuits to recognize errors and prevent a premature opening of the elevator door.