Abstract: The invention relates to a centrifugal compressor comprising an impeller not comprising distributor blading upstream of the impeller, a pressure probe and regulator means controlled by the probe and arranged to act on the flow conditions downstream or upstream of the compressor to avoid the risk of surging. The probe is disposed upstream of the impeller of the compressor and being arranged to detect the critical direction of the absolute velocity of the fluid and to measure the critical value of the radial gradient of the static pressure beyond which the compressor runs the risk of being subjected to surging.

Abstract: The invention relates to a power take-off arrangement, particularly a power take-off arrangement from an engine, comprising a pump including a fixed casing defining an annular liquid chamber, a rotor with a vaned annulus rotatable in said annular liquid chamber and intended to be rotated over a relatively wide speed range, a liquid inlet to said annular chamber, a liquid outlet from said annular chamber, a gate between said inlet and said outlet intended to allow passage of the rotor thereby while obstructing the flow of liquid along said annular chamber externally of the vanes of the rotor, and means for maintaining the liquid outlet from said pump at a substantially constant pressure at speeds above a predetermined speed within said speed range.

Abstract: A pressure operated shut-off valve for controlling a pneumatic circuit for instance a supply passage of a pneumatic tool, in response to the motive air supply pressure. The valve comprises a valve body that is continuously biased in its closing direction by a spring means and in its opening diection by the motive air supply pressure. If the air pressure drops below a predetermined minimum value the valve is automatically shifted to a closed position by the load of the spring means. A valve body controlled passage means supplies pressure air to the rear end of the valve body as the latter occupies its closed position, thereby making the closed position stable.

Abstract: A centrifugal compressor has at least one stage with its own impeller shaft, an inlet and an outlet for gas, and an epicyclic gear train for driving the impeller shaft. The epicyclic gear train comprises three members, a sun gear, a ring gear and a carrier on which a series of planet gears are mounted in mesh with the sun and ring gears. Means is provided for connecting a power input to one of the members of the epicyclic gear train, and means is provided connecting a second of the members to the impeller shaft. Means are provided for controlling the rotational speed of the third of the members to vary the speed of the impeller shaft of the compressor, and actuating means are provided for actuating the control means in response to the pressure of the compressed gas at the outlet.

Abstract: A steam turbine installation includes a safety system located in the steam flow path having a stop valve located in the steam flow path upstream of the turbine and a vacuum break valve located in the stream flow path downstream of the turbine, and a combined regulating and safety device connected to the turbine produces signals for controlling these valves. In addition, a signal from a steam flow monitor located downstream of the stop valve is supplied to a logic system, this signal having a value which normally corresponds to the setting of the stop valve. In the event of a disparity the logic system functions to trip the regulating and safety device which results in a closure of the stop valve and a partial opening of the vacuum break valve.