Abstract: A gas turbine engine comprises turbine and compressor elements on a rotary shaft. The shaft is rotably mounted on preloaded axial thrust bearings. As it rotates in use the turbine and compressor elements create an axial thrust load on the bearings. According to the invention that axial thrust load is opposed by an electromagnetic coil which is energised to exert an axial force on the shaft in opposition to the axial thrust load and preferably completely balancing the axial thrust load. Bearing life is much extended.

Abstract: A gas turbine engine driven auxiliary electric power unit which includes a turbine (9), an air compressor (7) for supplying compressed air to the turbine and driven by the turbine, fuel supplying means (2) for supplying gaseous fuel to the turbine, a generator (10) driven by the turbine for generating electrical output power which is fed to a main electric user supply (14), first detecting means (15) for monitoring turbine shaft speed, second detecting means (19) for monitoring the output power of the generator, first modulating means (16,18,13) for modulating the turbine shaft speed to cause it to coincide with a predetermined shaft speed (17) by means of controlling current flow from the generator to the main electric user supply, and second modulating means (20,22,23) for modulating the flow of gaseous fuel which is supplied from the fuel supplying means to the turbine so as to cause the monitored output power to coincide with a predetermined output power (21).

Abstract: A gaseous fuel compression and control system for gas turbine engine (30) comprises a screw compressor (10) driven by an electric motor (11) for feeding gaseous fuel to the gas turbine engine, and a modulating device (12) for modulating the rotational speed of the motor by controlling the frequency of electric power to the motor in response to sensed output power of the gas turbine engine.