Abstract: This invention relates to a closure for the outlet of a fan. A fan has an outlet opening 12 in a fan case volute 10 which is closed by a hinged flap 13, the weight of the flap being compensated by a counterweight arm 15. When the flap 13 closes opening 12, counterweight arm 15 is latched by latch 32 carried by spring 26 which must deform before the flap can open. Alternatively, the latch 32 is itself a resilient spring. The flap will only open when sufficient static pressure is applied by the fan, and the resilient latch 25, 32 will prevent "flutter" which might be otherwise caused by outside air currents.

Abstract: A primary member for a linear induction motor is disclosed comprising a frame having a pair of spaced parallel frame members, a core located between and supported by the frame members, and a motor winding carried by the core. The winding includes a plurality of turns each of which includes a pair of parallel portions supported located in slots in the core and which are interconnected by end windings projecting beyond opposite sides of the core. Each end winding has direction-reversing knuckle portion. Side cover assemblies extend along either side of the core to cover the end winding. Cooling means are provided, a first set of which are located between the frame members and a second set of which are located laterally outboard of and to either side of the frame members.