Abstract: A motorized trolley (10) for suspension from and travel on a rail (12) comprises first and second supporting wheels (14) for location on and engagement with opposite sides of the rail; the first supporting wheel comprising a first shaft (18-1) for rotating the first wheel (14-1) and the second supporting wheel (14-2) comprising a second shaft (18-2) for rotating the second wheel. Driving motors (16) are associated with the shafts for rotating the supporting wheels. Third and fourth supporting wheels may also be driven by motor. The motors are directly connected to the shafts of the supporting wheels.

Abstract: A magnetic hysteresis clutch comprises a rotor supporting a ferromagnetic hysteresis material and a rotary magnetic inductor capable of inducing a magnetic field in the ferromagnetic hysteresis. The magnetic inductor and the ferromagnetic hysteresis clutch is constructed so that an increase in the magnetization losses in the ferromagnetic material, which accompanies an increase in the slip between magnetic inductor and the ferromagnetic hysteresis, leads to a reversible increase in the temperature of the ferromagnetic hysteresis material, and thereby to a reversible decrease in magnetization of the ferromagnetic material which is sufficient to bring about a desired decrease in the transmitted torque. Thus it is possible to provide a magnetic hysteresis clutch in which the transmitted torque reversibly decreases when the slip increases.

Abstract: A magnetic hysteresis clutch comprises an external rotor and a rotary magnetic inductor arranged in said external rotor so as to define a radial air gap. Rings of ferromagnetic hysteresis material are mounted in said external rotor so as to be able to undergo a reversible thermal expansion of their internal diameter leading to an increase in the radial air gap. The clutch is designed so that the heating up of the ferromagnetic material in the rings which accompanies an increase of the slip between the external rotor and the rotary magnetic inductor, produces a reversible increase in the radial air gap which is sufficient to decrease the transmitted torque. Thus it is possible to provide a magnetic hysteresis clutch in which the transmitted torque reversibly decreases when the slip increases.

Abstract: Ventilation and heat exchanging system for premises housing animals, especially poultry, the system having one or more fans, one or more ducts for outgoing air which extends through an inner ceiling to a general collecting air flue, on the sides of which connect two vertically spaced sheets the space between which are connected to the collecting air flue, and behind the outer sheet which functions as a heat exchange sheet there opens one or more ducts for air intake (7) through an inner ceiling. Of the mentioned sheets the lower surface of the inner sheet is equipped by a heat insulating layer (4), the heat insulating ability of which at least in the vicinity of the ducts for incoming and outgoing air (1 and 7) in essence corresponds with the heat insulating ability normally required by an inner ceiling.