Abstract: An arrangement to provide variation of the speed or other operating parameters of an electrical machine without connection to the rotor. The machine is of the induction type having a winding in separate parts to create a flux movable in the air-gap different speeds by the alteration of current in a part of the winding. In one example the current is altered by a variable impedance connected to one winding part, the other part being connected to an electrical supply.Another example, FIG. 6, shows two machines (NM.sub.1, NM.sub.2) arranged to drive a rail vehicle through smooth rail wheels attached to the machine rotor axles. A single, variable-frequency, inverter (NI) drives both machines and is connected to part (MP) of each machine winding. Other parts (AP) of each machine winding are connected together by a link (NC). In operation power (real or reactive) is transferred between the machines along the link to equalize the torque of the machines.

Abstract: A system for sorting non-ferromagnetic metals from a mixture of material containing such metals and rubber and plastics material including a conveyor belt system and an associated linear induction motor the frequency and power of operation of which is chosen to deflect selected metals from the conveyor belt. The linear induction motor is placed beneath the conveyor belt and oriented with respect to the conveyor to produce a field of magnetomotive force in which the lines of the magnetic field are at right angles to the direction of motion of the conveyor, and in which the direction of travel of the field is orthogonal to both the lines of force and the direction of motion of the conveyor. The mixture of material subjected to the force of the linear induction motor may initially be treated by presizing or flattening, to enhance the effectivity of the induction motor in separating non-ferromagnetic material.

Abstract: In a method of, and apparatus for, extracting energy from waves on a liquid, the precession of a gyroscope in response to angular motion of a member in response to waves performs useful work by operating a hydraulic pump.Advantageously, pairs of gyroscopes having their rotors spinning in opposite directions are mounted in the member so as to balance the output torques of the gyroscopes.