A composite shaft comprising at least two axial segments of dissimilar materials, the segments being held together by a central tie-bar, wherein a segment of material least subject to radial expansion is provided with a coaxial male member extending axially from its end, and the cooperating segment subject to greater radial expansion is provided with a female skirt shrunk onto the male member in the assembly of the shaft and also being provided with an annular upstand, at or towards its peripheral edge and directed towards the cooperating segment, the upstand being held by the compressive force of the tie-bar always in full annular contact with its cooperating segment. The male member is of smallest practicable diameter and the upstand is of largest practicable diameter.

An open stator axial flux asynchronous induction electric motor has an open stator having two spaced insulating supports with a slot extending from a periphery of each of the supports to an inner location. A plurality of poles extend between and are secured to the supports. The stator has either distributed winding or salient phase pole windings associated with at least some of the poles with an opening between adjacent poles in the regions of the slots in the supports. The motor has a rotor with a shaft extending through the slots and at right angles to the supports. Two spaced rotor discs are present on the shaft and are located at either side of the stator. Each disc is made of a magnetically permeable material and has either an inner face of electrically conductive material or an inner face with conductive paths which function as rotor windings.

A high-temperature gas turbine includes a compressor, and a turbine coupled to the compressor, the turbine being capable of rotating at a high speed by a gas of firing temperature generated by a combustor. The compressor includes a combined type rotor shaft and blades of at least 15 stages which are implanted in the combined type rotor shaft. The compressor compresses air to a temperature of 400.degree. C. or above. The combined type rotor shaft is made of Ni--Cr--Mo--V low alloy steel having all bainitic microstructure whose composition consists, as analyzed in weight percent, of 0.15-0.40% C, 0.1% or less Si, 0.5% or less Mn, 1.5-2.5% Ni, 0.8-2.5% Cr, 0.8-2.0% Mo, 0.1-0.35% V and the balance substantially of Fe.

A vacuum pump has two shafts (3, 4) and two rotors (1, 2) which co-operate with each other and which are fixed to the shafts. The rotors are cantilevered on the shafts. The rotors are fixed to the shafts in a manner which is devoid of backlash, even during temperature changes. In order to achieve this, the shafts (3, 4) are made of a material having a modulus of elasticity which is as high as possible, e.g., steel. The rotors (1, 2) are made of a material having a density which is as low as possible, e.g., aluminum or a titanium alloy. Structures (8; 11, 12, 13; 14, 15; 25, 27; 38, 41; 43, 44, 45; etc.) are provided to ensure that the rotors (1, 2) are fixed to the shafts (3, 4) in a manner which is devoid of backlash at all operating temperatures.

A method of assembling a hinge conveyor chain includes providing adjacent conveyor links formed from a ferritic-pearlitic stainless steel, wherein the adjacent links have interdigitating link ends with openings for receiving a pin, and inserting a pin having a radially outwardly facing surface formed from a steel alloy with more than 0.6 wt. % of carbon and more than 12 wt. % of Cr through the openings of the interdigitating link ends to pivotally link the adjacent links.