Abstract: In a hydraulic pump and turbine system, the angular setting of the spray cone blades of the pump can be adjusted without any detrimental vibratory action during actual operation of the pump, this being obtained by closing, during said adjustment and without stopping the movement of the pump rotor, a valve, preferably a sleeve valve, inserted in the pump delivery channel between the pump rotor and the spray cone.

Abstract: In electrical discharge machining, an electrode is displaced towards a workpiece at a rate controlled as a function of the sparking conditions. The relative position of the electrode and workpiece is measured and, beyond a preset reference relative position, advance of the electrode is slowed as a function of the displacement past the reference position, or is stopped at the reference position, while continuing sparking and allowing withdrawal of the electrode if necessitated by the sparking conditions.

Abstract: In a hydraulic plant comprising one or more machines of the reaction turbine or rotary pump type, the conventional single spiral casing of each machine is replaced by several partial volutes connecting the periphery of the fixed supporting blade ring by several independent tubular connection elements to a pressure pipeline.

Abstract: A hydraulic machine combining a pump and a turbine has pump and turbine runners keyed on a common shaft and designed for the same direction of rotation. The pump is connected to a head by at least two partial volutes, and the turbine by at least two partial volutes wound in opposite direction to those of the pump. Sleeve valves between the runners and their partial volutes enable draining of the pump during turbine operation, and vice versa.

Abstract: A valve shutter is fitted in a channel and is adapted to be shifted, between a valve-opening position and an intermediate position facing a seat provided in the valve body, through rotation around a transverse axis, while the channel is set under still water conditions. The actual fluidtight application of the valve shutter against its seat is ensured by the pressure of the upstream water when normal flow conditions are restored. This dual movement is possible due to the fact that the shutter supports or bearings are resiliently or pneumatically held in position with reference to the valve body.

Abstract: A pulse generator for an electro-erosion machining apparatus wherein electrical discharges occur at a machining zone formed between an electrode workpiece and an electrode tool, the pulse generator comprising a capacitor charged from a source of direct current through an inductance and a switch for discharging the capacitor through the primary of a transformer, the electrode tool and the workpiece being connected across the secondary of the transformer, the capacitor being charged at a predetermined current rate and being discharged when the voltage across the capacitor reaches a preset level.

Abstract: Support and guiding means for a wire electrode in an electro-erosion machining apparatus comprising a V-block support and guide having two angularly disposed guiding surfaces substantially parallel to the wire electrode longitudinal axis mounted on a base automatically orientable radially about the wire longitudinal axis such that the axis of a linear cut through the workpiece or, alternatively, the tangent of a curvilinear cut substantially bisects the angle formed by the two angularly disposed guiding surfaces.

Abstract: An electro-erosion process and apparatus for improving the rate of material removal from a workpiece and for decreasing the rate of wear of the electrode tool in an electrical discharge machining apparatus, by controlling the average value of the machining current across the machining gap between the electrode tool and the workpiece by providing cut-off time intervals between consecutive pulse trains at a frequency of at least 200 Hz, and by controllably varying at least one of the parameters of operation consisting of the number of the pulses included within a single pulse train, the duration of application of said pulses within a single pulse train, and at least the longest of the intervals of time comprised between two consecutive voltage pulses.

Abstract: A tool holder assembly, particularly for holding an electrode tool on the end of the quill or ram of an electro-erosion machining apparatus, comprising a tapered bore disposed at the end of the quill or ram and a taper-shank electrode tool fitting the tapered bore, combined with manually releasable spring biased means for exerting on the electrode tool taper-shank a force urging it into engagement with the tapered bore, and with manually operable means for exerting on the electrode tool taper-shank a force in an opposite direction for disconnecting the taper-shank from the tapered bore. Angular positioning abutment means are also provided for angularly locating the electrode tool in the holder assembly.