Abstract: The invention relates to a nozzle (10) for dispensing concrete, mortar or the like, comprising a housing (12) and a mixing chamber (14) which is arranged therein and is delimited by a circumferential wall (16) and extends along a longitudinal axis (L) at least between a supply opening (19) and an outlet opening (20); an actively driveable mixing device, which is arranged in the mixing chamber (14); and an exit opening (32), which is directly or indirectly flow-connected to the outlet opening (20) of the mixing chamber (14). At least one cavity (44; 44a, 44b), which extends axially and in the circumferential direction, is arranged around the circumferential wall (16) of the mixing chamber (14) and is in contact with the circumferential wall (16) and at least substantially surrounds the mixing chamber (14) in the circumferential direction.

Abstract: The invention concerns a tension roller made of a plastic material for adjusting a tension in a belt drive, comprising a wheel (7) having an inner ring (9) and an outer ring (10) connected to each other by axially oriented, circumferentially spaced ribs (12) and by a central web (8), the wheel (7) being rotatably mounted on a support element (2) which bears by a running face against the belt (3). According to the invention, successive ribs (12) enclose different angles with reference to a central point of the wheel.