Abstract: The invention provides an expansible cannula (particularly useful as a trocar) comprising essentially a conical tube made of metal foil with its proximal end located in a holder, and an expander tube which can be pushed through the stem from the proximal end, to cause the stem to expand from its conical free condition to a distended cylindrical condition. The stem itself comprises a caudex which has only radial motion on expansion of the stem, and a leaf, which in addition to uncoiling on expansion of the stem is also permitted a degree of forward motion, so that the front end of the stem becomes circular in the opened condition.

Abstract: The invention relates to a surgical cannula for introducing instruments, scopes or tubing into body cavities or organs. The cannula comprises a conical tubular stem which is formed of thin sheet material, such as beryllium copper, the sheet material being coiled or partially coiled so that if is capable of opening up from a closed condition by reducing the cone angle, thereby increasing the diameter of the stem at the distal end.In the preferred arrangement, the proximal end of the stem is clamped between two tubular elements fitted one inside the other.The invention also includes the combination of the expansible cannula and a guide rod adapted to pass through the stem and bored throughout its length to receive a guide wire. The guide rod may have a slightly enlarged distal end and the arrangement be such that passage of the enlarged distal end through the distal end of the stem causes a slight opening out of the distal end to allow passage of the enlargement.

Abstract: The invention relates to a surgical appliance for forming an opening through the skin of a patient and for distending the opening so formed. The appliance takes the form of a trocar which may comprise two separate components or two component portions formed by openings in a tube extending partially along the tube from the distal end. In either case, the components or component portions are preloaded towards a closed condition, but can be expanded into an open condition, for example by forcing a tubular expander into the trocar from the proximal end. The preloading of the trocar may be by a resilient sleeve surrounding the components or by a "set" introduced into the material forming the components. A cutting edge may be formed across substantially the full width of the distal end of the trocar and it is preferred that in the open condition, there is a no significant increase in the cross-section of the trocar towards the distal end.

Abstract: A fluid-operated ram, for example comprising a cylinder 10 and piston 12, is provided for actuating a device such as a chuck having jaws 15. When the jaws are moved by the ram to grip a workpiece this constitutes a limiting position which impedes the flow of fluid thus causing a build-up of fluid pressure within the ram. This build-up can be detected to give an indication as to when a workpiece has been securely and safely gripped. To ensure that a false indication is not given if the ram reaches an end of its working stroke before the workpiece is securely gripped, means (22) are provided to relieve pressure within the ram when the ram reaches an end of its working stroke.

Abstract: An apparatus is provided which enables the jaws of a chuck 10 to be removed from and inserted into jaw-ways 12, 13, 14 using a conventional workpiece handler, rather than a sophisticated and highly accurate dedicated jaw handling mechanism. A conventional workpiece handler cannot position a jaw to close tolerances but this problem is overcome by using a guide shoe 17 which can receive a jaw from the workpiece handler in any one of a range of positions and then accurately guide the jaw into one of the jaw-ways 12, 13, or 14.A mechanism 16 is provided for releasing the jaws from the jaw-ways, and for re-locking the jaws in position.

Abstract: A work holding device comprises an annular cylinder 14, an annular piston 15 movable with respect to the cylinder within the cylinder in an axial direction by application of fluid pressure, and a jaw drive device 28, 29, 30, 31 projecting from the cylinder 14 for applying radial movement to a work holding jaw 12, 13. The piston and/or the cylinder co-operates with the jaw drive device within the cylinder such that axial movement of the piston with respect to the cylinder causes radial movement of the jaw drive device. Since the translation of axial to radial movement takes place effectively within the cylinder, it is possible to reduce the axial length of the work holding device as compared to known work holding devices in which translational movement occurs outside the cylinder.

Abstract: A chuck comprises a body (10) rotatable about an axis (11) and at least one jaw (12) movable in a radial direction to clamp a workpiece in the chuck. At least one operating lever (14) is mounted on the body (10) and the, or each, lever is operable to move a jaw (12) radially. The, or each, lever is also movable axially with respect to the chuck body (10), to disengage from the associated jaw (12), enabling the associated jaw (12) to be removed simply and quickly from the chuck body (10) by movement in the radial direction.

Abstract: A workholding device comprises a body 10, a plurality of relatively movable base jaws 12, each base jaw 12 carrying one of a plurality of top jaws 13, such that when the base jaws 12 are moved relative to one another, a workpiece 15 can be gripped by the top jaws 13, and a sensing device 14 positioned to sense force transmitted from a top jaw 13 to a base jaw 12. Preferably a second sensing device 16 is provided to sense centrifugal force to permit compensation for its effect on the top jaws, so that a signal can be obtained which is an accurate measure of the force prevailing between the top jaws 13 and the workpiece 15.

Abstract: In a gas-tight sealing device for rotary gas-liquid contacting apparatus, a liquid channel takes excess sealing liquid away from the seal to reduce viscous drag.

Abstract: A solid bowl decanter centrifuge of the scroll discharge type comprises a solid bowl which rotates at a first speed, and a scroll conveyor which is rotated within the bowl at a second, slightly different speed for conveying separated solids to a solids discharge end of the bowl. The suspension to be centrifuges, substantially unmixed with a flocculant, is introduced by a stationary feed pipe into a feed compartment which is a radial passage in the conveyor. The feed compartment provides high turbulence and shear forces which mix and expel the suspension and flocculant into the bowl before flocs have formed.

Abstract: A solid bowl decanter centrifuge comprising a solid, generally cylindrical bowl having a liquids outlet at one end and a solids outlet at the other end, and adapted to be rotated at a first speed. Inlet pipework enables influent to be introduced to the interior of the bowl. A scroll conveyor is mounted for rotation within the bowl at a second speed. A first motor has its output shaft coupled to the scroll conveyor whereby the motor speed determines the differential speed of the conveyor relative to the bowl. A control mechanism is adapted to measure the torque applied to the scroll conveyor and to control the speed of the scroll conveyor in dependence upon the measured torque, a second pump being adapted to pump flocculant into said inlet pipework at a rate dependent upon the torque controlled differential speed of the scroll conveyor.

Abstract: A solid bowl decanter centrifuge comprising a solid, generally cylindrical bowl having a liquids outlet at one end and a solids outlet at the other end. A drive for rotating the bowl at a first speed. Inlet pipework for introducing influent to the interior of the bowl and a feed valve in the inlet pipework for controlling the rate of flow of influent therethrough. A scroll conveyor mounted for rotation within the bowl at a second speed. A hydraulic motor whose body is connected to the bowl and whose output shaft is connected to the scroll conveyor whereby the motor speed determines the differential speed of the conveyor relative to the bowl. The hydraulic motor has a hydraulic drive system which includes a pump for supplying hydraulic fluid to the motor.

Abstract: A pendulum suspended, hydraulically driven basket centrifuge comprises a centrifuge basket adapted to be rotated about a vertical axis by a hydraulic motor. The basket is mounted on the upper end of a vertically extending main spindle which is journalled within a cylindrical casing by means of two bearing assemblies disposed at upper and lower portions on the spindle, respectively. The hydraulic motor, the casing, the bearing assemblies and the main spindle are constructed as a cartridge unit which can be removed from the basket as a complete sub-assembly.

Abstract: The invention concerns scroll discharge decanter centrifuges of the type in which the interior of the centrifuge is to be kept sealed from the atmosphere and which comprise a stationary assembly which includes an outer casing, a rotary assembly which includes a solid bowl which is adapted to be rotated within the stationary casing at a first speed and a scroll conveyor which is rotatable within the bowl at a second, slightly different speed. A plurality of sealing devices are arranged to be effective between the rotary assembly and the stationary assembly. Each sealing device comprises a first ring fixed relative to the stationary assembly and a second, coaxial ring which is adapted to rotate with the rotary assembly. That surface of the first ring which faces the second ring contains a plurality of gas jet nozzles by way of which pressurized gas can be supplied to an annular clearance gap between the first and second rings.

Abstract: In a disc bowl centrifuge, means are provided for introducing pressure fluid into a piston chamber serving to operate a discharge valve controlling outlet of processed material from the bowl, which means are such as to allow a pressure substantially higher than atmosphere and sufficient to hold the discharge valve closed against the opening forces exerted thereon by process material subjected to centrifugal force in the bowl.